/ohm/ - electronics general, semi-dodgy lamp edition

[Anonymous No.1423156]

flat thread: >>1416580

>I'm new to electronics, where to get started?
There are several good books and YouTube channels that are commonly recommended for beginners and those wanting to learn more, many with advanced techniques. The best way to get involved in electronics is just to make stuff. Don't be afraid to get your hands dirty.

>Books?
Beginner:
Forrest Mims III, Getting Started in Electronics
Charles Platt, Make: Electronics
Michael Jay Geier, How to Diagnose & Fix Everything Electronic

Intermediate:
Kybett & Boysen, All New Electronics Self-Teaching Guide
Paul Scherz and Simon Monk, Practical Electronics for Inventors

Advanced:
Paul Horowitz and Winfield Hill, The Art of Electronics

>YouTube?
mjlorton
BigClive
paceworldwide
eevblog
EcProjects
greatscottlab
AfroTechMods
Photonvids
sdgelectronics
TheSignalPathBlog

>Project/idea websites?
http://adafruit.com
http://instructables.com/tag/type-id/category-technology/
http://makezine.com/category/electronics/

>Components/equipment sources?
Mouser, Digi-Key, Arrow, Newark are global full-line distributors with small/no minimum order.
RS Components (Europe)
eBay/AliExpress sellers, especially good for component assortments/sample kits (caveat emptor)
Your local independent retail electronics distributors
ladyada.net/library/procure/hobbyist.html

>Circuit simulators?
This mostly comes down to personal preference. These are the most common ones though:
LTSpice
CircuitJS (quick, dirty, interactive)
NI Multisim
CircuitLab
iCircuit for Macs

>PCB layout software?
KiCAD (recommended), why use anything else

>My circuit doesn't work. Halp?
Check wiring, soldering, part pinouts, and board artwork if applicable, then post schematic. Supply ALL relevant info and component values when asking for help.
>Li+/LiPo batteries
Read this fine resource first: https://www.robotshop.com/media/files/pdf/hyperion-g5-50c-3s-1100mah-lipo-battery-User-Guide.pdf
>I have junk, what do?
Take it to the recycler.

[Anonymous No.1423161]

this thread's digits brought to you in part by the TPA3156D2 70W class-D audio amp

[Anonymous No.1423163]

>>1423156
>>>1423159
So besides shoving them on my butt, what I could do with those chargers? the transformers are shit because they are teeny weensy. I'm repurposing a washing machine motor as a grinder but I have no idea of what to do with the chargers.

[Anonymous No.1423167]

>>1423163

the proper attitude is ''i have a need, how do i achieve it''
the incorrect attitude is ''i have some junk, how do i create a need for it''
deviant attitudes are not allowed in /diy/ so you must leave.

[Anonymous No.1423173]

>>1423167
>/diy/
>home of the 6 axis dildo bot
>not deviant
and besides; everyone here, including myself, shoves stuff up their butts now and then. I'm no homo tho.

[Anonymous No.1423175]

Thanks anon >>1423156
I already posted it in /g/ but here is my improved fender blinker led i came up with.

[Anonymous No.1423178]

>>1423175 improved because this one will sit flush in the holder. because i put the led on the wider side.

[Anonymous No.1423180]

>>1423178
and tucked the wires out of the way.
Pic related is the first one I made.

[Anonymous No.1423181]

>>1423180

[Anonymous No.1423183]

>>1423181
Almost right. An amber led could make it perfect.

[Anonymous No.1423190]

I have an ads1015 and a chinese arduino nano.
the ads1015 is supposed to be able to sample at 3.3khz. But the max Im able to get is about 2khz.
I add the line
> TWBR = ((16000000 / 400000L) - 16) / 2;
to set the i2c speed to 400khz but the read/write combined takes about 300us. I had to add a delay of 200us to get it to not spit out garbage.
Anyone here can tell me how I can increase the sample rate of the ads1015. I modified the arduino playground lib so that theres a function to set the sample speed and the delay along with changing the delays to delaymicroseconds.

[Anonymous No.1423200]

>>1423173
>implying the norms of a bunch of dried-up boomers have any legitimacy

>>1423163
tbqh that seems like the best course

>>1423175
seems like you're generating quite a bit of heat in there, with the resistor glued to the LED, which isn't worth worrying over unless it's meant to come half-on when your headlights are on. other than that, decent

>>1423190
how are you setting the ADS1015 config register?

[Anonymous No.1423220]

found this, I think it was from a fan. How do i wire it? The capacitor seems to be already connected to it. I tried conecting the red and yellow to main but it went smoky and bang. Tried googling the part number and the company and I can't find anything.

[Beppu !n/ZnkB9jUw No.1423222]

A couple (stupid) questions:

1) For a multimeter, the A plugs are the only ones that are fuses, right? Like if I have the red lead plugged into V and touch something pulling 20A, it won’t blow the 10A fuse, yes?

2) I forgot I had the lead plugged into the 500mA hole and touched a car battery and blew that white fuse. Looked around Home Depot and the only thing they had that looked real similar were these “Microwave Fuses” but were like 5A+. So I grabbed these quick-blow 500mA fuses but they’re only rated to 250V whereas the original 500mA fuse is rated to 1000V. Will it work fine until I get the OE replacements from the interwebs?

I figure it’s better to go with the 0.5A/250V than the 10A/1000V to replace the 0.5A/1000V.

[Anonymous No.1423226]

>>1423220
Red to yellow resistance is 70-60 ohms
red to white is 100ohms or so
yellow to white is 10-20 ohms

[Anonymous No.1423233]

>>1423222
yes, as long as you don't exceed that 250V

[Beppu !n/ZnkB9jUw No.1423240]

>>1423233
Cool. Working on the cars and household stuff, I probably won’t go above 250V. Plus it’s on the <500mA plug so I’m guessing that will be lighter stuff. I should order it before I forget. And if I go >250V on that plug, the worst thing is the fuse blows and I got a 5pk of those fuses for like $2 since they didn’t have singles.

[Anonymous No.1423247]

>>1423240
the fuse won't do anything if you go above 250V, it doesn't also blow at 250V, it just isn't guaranteed to actually blow at 500mA if you go above that; it's up to you to make sure you don't exceed that voltage

[Beppu !n/ZnkB9jUw No.1423255]

>>1423247
Another dumb question: simple continuity test is a good way of testing a fuse, right? I was reading smth online about resistance and the continuity seemed easiest.

[Anonymous No.1423256]

>>1423220
>it went smoky and bang
probably won't matter which way you connect it now
black and white are line (hot) and neutral

[Anonymous No.1423260]

>>1423255
yup, continuity works fine

[Anonymous No.1423264]

>>1423256
so how do I wire it? connect black and white to the line and the other to the neutral? what about the other two? it's a single phase motor

[Anonymous No.1423265]

>>1423200
>how are you setting the ADS1015 config register?
I commented out the default setting of 1600 sps and added on the next line.
> config |= m_sps;
I have a function that sets m_sps and its an enum of the sample rate values.

[Beppu !n/ZnkB9jUw No.1423286]

Another random question- why do these iPhone lightning cables crap out after 6mos or a year? Even the OE and $35 Tuff Cable do it. The end of this orange one reads ~4.8V just like a good white one so it has power.

I’m trying to play with the DC amp function. This was one of the cables that crapped out after some use but I was trying to get it to work a couple more times instead of destroying a good cable. Interesting part is it the meter reads 40mA after plugging it into the AC adapter, then reads 100-120mA after plugging it into the phone. But the phone doesn’t show the little lightning bolt.

There’s 3 smaller cables inside the lighning cables so would it be (+), then some data in the middle, then (-)?

[Anonymous No.1423335]

>>1423226
>>1423264
no, black to line and white to neutral

[Anonymous No.1423371]

>>1423183
Without a heatsink, the LED is going to burn out very quickly.

[Anonymous No.1423399]

TS-100 BTFO?
https://www.tindie.com/products/vlk/rt-soldering-pen/

[Anonymous No.1423401]

how much could I reasonably expect to sell this fat piece of shit for? I've had it for about 9 months now and have had about as much as I can take of it. Everything works perfectly, I put in a new NVRAM chip, and it'd come with two HP 10M probes.

[Anonymous No.1423408]

>>1423399
Doesn't come with a case? Or do you just use it like that with no strain relief?

Are 3.5mm weller tips common/good?

[Anonymous No.1423432]

>>1423401
eBay's prices for working ones in decent condition seem to be around $100-$200.
Not too sure whether the pricing is based on the idea that anyone wanting that scope is a collector and thus willing to pay, or that anyone wanting that scope is a retard who can't read the manual.

[Anonymous No.1423438]

>>1423408
RT series tips look like they're god-tier for fine SMT work (options include 0.4mm chisel, 0.1mm conical, 0.2mm needle) and the "tip" includes a grip. about $20-30 per so a bit spendy, but if you work with 0201s it's probably good/necessary shit

[Anonymous No.1423439]

>>1423200
>>1423371

It not ideal but should be ok. The light is only used when indicating. The resistor is more a heat soak if anything. The resistor runs about 1.2w but its only on half the time so .6w of heat generated on average. Then blinkers are on for maybe a minute at a time at most. The total power is about 300ma on 13 volts or so. If anyone is really interested i can measure the exact values.

Even if the leds would last 10 hours its more than enough for many years of driving.

[Anonymous No.1423440]

>>1423432
Probably more of the latter, given that the slightly higher end/newer HP models of that era routinely go for $400+. Would I be better off selling off the scope and keeping the probes for when I get an actual decent, new DSO?

[Anonymous No.1423443]

>>1423335
by black you mean gray right? because the black wire is connected to the capacitor and it goes straight into the engine. pls no bully I'm retarded

[Anonymous No.1423444]

>>1423222
Glass fuses won't extinguish any arcing and can spall the filament everywhere if they explode. Nevermind the shrapnel if anything escapes the casing. They use sand-filled ceramic fuses for a reason.
>I figure it’s better to go with the 0.5A/250V
Marginally, given it's the wrong type of fuse for the application.
>than the 10A/1000V
May as well be sticking a steel rod into the fuse holder and calling it a day.

[Anonymous No.1423445]

>>1423438
Then what's the go-to tip series for larger stuff

We really need a /ohm/ tip spreadsheet.

[Anonymous No.1423447]

>>1423439
oh, the wing light. you'll be fine

>>1423445
Hakko 900-M, my dude. cheap, ubiquitous, widely cloned, and still useful for SMT. you can do 0402s with them, if you also bring flux, tweezers, patience, and swearing

[Anonymous No.1423450]

>>1423447
Those 3.5mm tips are probably so expensive because each one has a heater and thermocouple inside, so it isn't really surprising.

It doesn't look too easy to homebrew a chassis to hold those Hakko elements.

[Anonymous No.1423462]

>>1423443
well aparently the correct connection was red->live white and yellow neutral. but it got angry on the last test and burnt out.

[Anonymous No.1423478]

I have this old roland electrical piano which works fine with headphones but when playing through the speakers everything seems fine except for the right speaker. The right speaker seems to have 3 states, sometimes there is nothing, not even on the scope, sometimes it is acting normal and sometimes it sounds like there is some sort of resonation happening, it almost sounds like there is a resonating pile of coins on top of the piano but with all frequenties. I think this might just be a shitty cap because this piano is really old. Does anybody know of a way to check caps without desoldering them. Just by looking at signals when playing on the piano. I have a good digital oscilloscope and a multimeter.

[Anonymous No.1423479]

>>1423478
Forgot pic

[Anonymous No.1423486]

Hello, I want to make a circuit that turns a relay off when the thermistor gets too hot, and remains off until I turn it on again. Could pic related work?

[Anonymous No.1423491]

Might as well show off my brake light I prepared earlier.

[Anonymous No.1423494]

>>1423478
I'd say you have a bad contact somewhere.

[Anonymous No.1423507]

>>1423479
>>1423478
Swap your left speaker to the right speaker channel. See if the problem follows. If you have an oscilloscope, stop wasting your time trying to eyeball the fault and do some actual troubleshooting by tracing the signal chain from the output of the signal generators through the amp. See where the fault manifests, test the components within that block. What are you even doing with diagnostic equipment if you are not prepared to use it?

[Anonymous No.1423516]

when discharging 18650s with a 10ohm resistor, should i measure the voltage under load and consider the battery discharged when it is 3.0V, or does the voltage need to be 3.0V after the load is removed? this is not clear to me because voltage always slowly rises to some level when the load is removed

[Anonymous No.1423553]

is it possible to connect several smps in parallel to have higher currents? I'm thinking about some sort of active current balancing with opamps and transistors but having sources or terms to google would help.

[Anonymous No.1423559]

>>1423553
Yes, and it is a common way to build high-current switchers. It is normally done with switchers specifically designed to be paralleled, with synchronized clocks and whatever is needed to make it work well.
You could google multiphase (parallelable) switchers.

[Anonymous No.1423560]

>>1422248
Tube pedal anon here. I'm back with tube voltages.
Nothing changes when the volume drops. The hair dryer trick works really well though.
I guess it's time to see if my scope works?

[Anonymous No.1423581]

Ay what up /diy/, /o/tist here.
I don't frequent diy as much as I should but I have a question.Tl;dr of situation:
>gf uses my motorcycle for a day
>full of bugs, she goes to her dad's house on the way back and washes it with a pressure washer
>tells me she washed it with a pressure washer and thanks me for use
>day after, headlight goes out at random times
>burning plastic smell
>think the bulb is fucked, go to replace
>connector looks like this
I'lI post a few other pics, it looks like it shorted out. It now doesn't work at all. I'lI be changing the bulb anyway but what would be the best option for addressing this? The bulb is a H4 if that matters. Will cutting the wires back a bit and buying a new connector suffice? How do I weatherproof connectors like this, if possible at all?

[Anonymous No.1423582]

>>1423581

[Anonymous No.1423583]

>>1423582

[Anonymous No.1423586]

>>1423583
Last pic. I think I covered all sides of the connector now

[Anonymous No.1423605]

>>1423516
bump, help a brainlet out

[Anonymous No.1423610]

>>1423486

yeah, looks alright. if you use the common 339 comparator or something from the same family, it needs a pull-up resistor on the output. also, you probably wanna have a trimmer pot to adjust the trip point.

[Anonymous No.1423613]

>>1423560
Nothing beats a scope. Excellent log btw.

[Anonymous No.1423615]

>>1423581

the water caused oxidation on the contacts, which meant their resistance went up, which caused heat to be dissipated at the contact point, which melted the plastic connector.

you could pull out the contacts and sand them back to clean metal as a temporary measure, but replacing the connector should be the ultimate goal.

as for weather-proofing, there's a million things including melted wax.

[Anonymous No.1423616]

>>1423581
You go down to your local auto parts store and buy whatever three conductor connector set strikes your fancy and use that.

>just take the wires back
That would depend if the wires are long enough to do it. You should inspect them and check voltages and resistance in your whole electric system. But if probably just got unlucky there

[Anonymous No.1423621]

>>1423610
thanks man. I have the 393 here at hand, or some normal op amps

[Anonymous No.1423687]

>>1423450
well, no. but you can pick up Hakko elements and handles for dirt cheap and control them as you like

>>1423560
ah, good thx. heater voltages look alright
>tube 2, pin 6, 129V
huh? that should be connected directly to V+ which should be 180 or so, unless the schematic lies. check for shorts, goop, other physical degradation in the vicinity of V2? trace and ensure that plate really is meant to go to the same V+ as everything else? or maybe it changed while you were measuring?

>>1423621
consider a D flip-flop with preset/clear as you can buy them in solo packages

[Anonymous No.1423716]

>>1423687
Oh, right.. I just didn't number the tubes correctly. Just gave them a number without thinking much of it..

[Anonymous No.1423738]

>>1423716
you need to be more careful about that, anon
anyway I think the two halves of V2 are swapped on the schematic. in that case, the "Tube 1" voltage readings make some sense
so you've got the hair dryer, can you narrow it down to a part of the circuit that is most responsive to heating? after finding the general area of the board, you could make a foil cone with ~1.5cm opening at the small end and attach it over the end of your hair dryer to pinpoint the problem component

[Anonymous No.1423744]

>>1423738
>you need to be more careful about that, anon
Sorry. I'm trying my best.
I did consider your method but I'm going to see if I can do it with my scope. It's an old Meguro. I've had it for more than a decade but only just tried firing it up now. The test signal isn't perfect, so I guess the probe is a bit out of whack. Shouldn't matter for this I guess.

[Anonymous No.1423746]

I was playing around with the idea of using a CD4017 IC to control my variable transistor base drive circuit. (>>1421397)

Pic related shows the general idea.
I realized a precise constant current sink can be formed with just a single op-amp, NPN transistor and a resistor. It could be used to control the base current (I_load) of the high power PNP. Then I could use a logic counter IC + resistor divider to form the reference voltage (U_adj) for the current sink.

[Anonymous No.1423750]

>>1423687
nah, I have a billion bjts and fets here. no need to be a buy fag when I can make one with two transistors

[Anonymous No.1423753]

>>1423746
You have invented a rather clumsy DAC.
If you want to retain the same basic idea, you could replace the 4017 with a small binary counter like 74hc161 and the diodes and resistors with an R-2R ladder or a bunch of binary-weighted resistors.
https://en.wikipedia.org/wiki/Resistor_ladder

[Anonymous No.1423756]

how do I find out what specs a thermistor has? It's a green turd with NTC 500-11 written on it. I know what NTC is but can't find any datasheets or manufacturer. it's about 16C here and it measures 100 ohms

[Anonymous No.1423761]

Could somebody please point me to site or something where i could find newer version of SEE Electrical?? I've been looking everywhere without any luck.

[Anonymous No.1423764]

>>1423761
Buy it or use the student version.

[Anonymous No.1423774]

>>1423746
if you need precision, consider a MOSFET whose basically zero gate current won't confound your current measurement

>>1423744
I know you really want to use that scope, but waveforms aren't going to tell you much of anything. a heat source and your ears would be the correct tool for troubleshooting heat-related problems

>>1423750
I think we did this circuit a few threads ago. why not just force the comparator to the desired fault state by pulling one of the inputs to ground or Vcc thru a diode or transistor?

>>1423756
you could calibrate it in an ice bath or boiling water

[Anonymous No.1423775]

>>1423756
NTC's nominal value is measured at 25C. If you measure the resistance at two different temperatures, you can calculate both the nominal value and the beta value from those.
https://en.wikipedia.org/wiki/Thermistor#B_or_%CE%B2_parameter_equation

The results will differ from the datasheet's values if you pick significantly different temperatures than the manufacturer.

[Anonymous No.1423787]

>>1423774
>waveforms aren't going to tell you much of anything
But I thought this was how audio guys did things. Follow the signal through the circuit.

[Anonymous No.1423789]

>>1423787
you certainly could do that, but if you're still going to need to heat the thing and supply an input signal to get it to malfunction... just how many hands have you got anyway?

[Anonymous No.1423794]

>>1423774
I don't understand what do you mean. That won't have hysterisis, will it?

[Anonymous No.1423802]

I've used this circuit to fade an LED on and off.
I noticed it's essentially rising and falling in a sine wave pattern.

I thought I might be able to use it as a synthesizer, but when I replace the LED with a capacitor and speaker, it produces no sound.
Am I mistaken in how this works, or am I just not setting the circuit up correctly to generate audio?

[Anonymous No.1423804]

>>1423789
I'm hoping the hold function on pic related will do the trick for the signal. A good blast with the hair dryer and I should be good for at least 5-10 minutes.
I'm finally going to make daddy proud. You'll see.

[Anonymous No.1423805]

>>1423802
the signal wouldnt be a sine wave, it would be an approximated triangular wave, and if you can see the fading, it is too low frequency for your ears to perceive it as audio

[Anonymous No.1423822]

When using a coupling capacitor, will a larger value result in a weaker signal?

I'm RGB modding a tv and the image is too bright.

On each input line (R,G, B) there is a 75ohm resistor tied into the ground, then a .1uf coupling capacitor (in line). I'm trying to figure out if say a .2uf coupling capacitor will make the image darker.

[Anonymous No.1423825]

>>1423822
Dont know about video, but impedance increases with smaller capacitors. So smaller caps => smaller signal.

[Anonymous No.1423826]

>>1423825

OK, so it sounds like I may actually need smaller caps than .1uf. Thanks.

[Anonymous No.1423829]

>>1423826
Also you should know that a cap and resistor create an RC filter which attenuates different parts of the signal differently depending on their frequency

[Anonymous No.1423867]

>>1423443
>by black you mean gray right?
yes - gray, red, and yellow are speed taps
white is neutral
white to neutral and ONE of the speed taps to hot
>it's off a 3 speed fan

[Anonymous No.1423868]

>>1423794
sort of. Pic related effectively turns off the pullup on the - input once the pulldown is turned on by the + input exceeding the - input, ensuring the + input always exceeds the - input and the output therefore stays pulled low until the button is pushed. you might be able to merge R1+R2 into R4+wire depending on how much current your transistor wants, hence the MOSFET

>>1423804
bretty gud, never thought of that

>>1423822
better to add some resistance to ground after the cap, or add some resistance inline. TVs use signal level references embedded in the composite signal which you appear to have bypassed, and you might want to reverse-engineer it a bit more to either bypass the AGC properly or push your green signal into it to provide that reference

[Anonymous No.1424009]

>>1423868
>better to add some resistance to ground after the cap, or add some resistance inline. TVs use signal level references embedded in the composite signal which you appear to have bypassed, and you might want to reverse-engineer it a bit more to either bypass the AGC properly or push your green signal into it to provide that reference

Sorry, I didn't detail the whole mod, the sync line ties into the tv's composite or a luma input, this sets the tv to the proper level, the RGB all tie into the tv's jungle chip, basically it uses the on screen menu to inject rgb into the set. If you're interested google rgb tv mod and it's the one over on the shmups.system11.org forum.

This damn image is still way too bright though, I need to do some more research.

[Anonymous No.1424019]

>>1423190
Bumping this question. I cant really find any examples of how to use the ads1015 besides the terrible adafruit one. I figured this would be a common adc and have decent documentation but Im really struggling. Has anyone used this or one of the ads10xx?

[Anonymous No.1424052]

Does anyone know how hard it would be for someone to 1.) monitor RPM with an arduino 2.) log the RPM at regular intervals and 3.) store the logged data with a time stamp on an SD card?

I already have a sensor set up that counts RPM so this is mainly a coding thing I think, unfortunately I have little experience with arduino, I can make a light blink and that's just about it

How hard would it be for me to learn the skills needed to do this from the ground up?

[Anonymous No.1424053]

>>1423401
I have one in my basement, Am giving it to a friend who doesn't have a scope. The 10 MSPS is quite shit, but it's better than nothing. I thought about selling it, but I wasn't keen on changing the NVRAM and line filter as I have another, perfectly fine working scope with better specs.

I still think I'll be somewhat sad to see it go, I love the big screen and the measurements it provided are real nice, providing statistics etc.

[Anonymous No.1424055]

>>1423265
are you running in continuous-conversion mode? if not, you probably should be
is there anything else on your I2C bus that might be slowing it down?

>>1424019
could you just throw together some code that talks I2C directly to it? the protocol looks pretty simple: to set up, I2C write a 1 byte followed by the config register contents establishing continuous conversion. then, to read, I2C write a 0 byte, I2C read two bytes of data, and it doesn't look like they even need to be in the same transaction

>>1424052
look up the SD library, which has a datalogger example
then, if you need interval support, check out the SimpleTimer library

[Anonymous No.1424060]

I was thinking it would be pretty easy to have an MP3 player that is just a microcontroller and a USB slot such that you can plug any USB flash-drive into it and play the music off it, with a small low-res display for folder navigation. Build it into a single-cell power-bank housing and you'd have a pretty compact device. Thoughts?

I've not messed around with playing files from a microcontroller, but how hard would it be to have it work on all the common USB formats and all the common audio formats?

[Anonymous No.1424101]

>>1424060

you wanna recreate a gadget they now sell in dollar stores for about $3? surely there are more worthy projects just waiting for someone to realize them.

[Anonymous No.1424104]

>>1424060
>all
that's not a question
look up Rockbox and stop fantasizing

[Anonymous No.1424108]

>>1423491
slow day at the office

[Anonymous No.1424113]

>>1424108
Shine

[Anonymous No.1424168]

>>1423516
please, anyone?

[Anonymous No.1424183]

I have some old Li+ batteries that are working just fine...Can I wire them together and make a power bank? What should I be concerned about?

[Anonymous No.1424186]

>>1424168
Idk. Why are you doing this? I would just go with worst case scenario, so under load.

[Anonymous No.1424189]

>>1424183
>Can I wire them together and make a power bank? What should I be concerned about?
sure

try to use the same size/brand/model cells in a single bank

[Anonymous No.1424191]

>>1423516
Whether intermittent test load or continuous test load is more representative depends on the intended end use. Either way, you measure the voltage when the load is still connected.

[Anonymous No.1424210]

So I got chinked, and I might be retarded but how the fuck do I connect wires to these banana plugs? the screws are hollow inside but I don't think I'm suposed to solder stuff in there.

[Anonymous No.1424211]

>>1424210

and of course my image

[Anonymous No.1424216]

>>1424189
Forgot to mention they are the phone batteries with protection circuits, does that change anything?

[Anonymous No.1424244]

>>1424210
>>1424211
solder it anyway

[Anonymous No.1424284]

>>1424113
Looks great. Are those some pre-built LED modules? What are the specifications?

[Anonymous No.1424293]

>>1424284
xcuse me

[Anonymous No.1424407]

>>1423560
>>1423868
Things aren't going so well.. Now it's fugged all the time. Trying to figure out things with my scope but it would probably help to know more about how the circuit works.
I'm getting a decent signal right before r34 but after I can't see anything. Output of u4a looks ok though. So does the output of u4b. Haven't gotten any further yet.

[Anonymous No.1424423]

>>1424186
>>1424191
thanks for the answers, i need to measure the capacity without an advanced charger with the built-in discharge function, hence i need to know the point at which to unplug the resistor

[Anonymous No.1424429]

why do stereo/surround sound audio systems sometimes require you to connect the speakers by coiling together the positive and negative copper wires and then putting them through a mechanism that clips them in? it's difficult to connect them in such a way that the signal is clear and if you move the wire just a little bit, it might make something loose and the signal is not 100%.

this is so inconvenient. why don't companies just put connectors on the speaker wires so you can simply plug them in without any loose connection issues?

[Anonymous No.1424447]

found the remains of a old tube tv, transformers were taken and valves smashed but I got the main board. Can someone tell me what the fuck is this thing with a hose coming out of it?

[Anonymous No.1424449]

>>1424447
Fuck my image.

[Anonymous No.1424451]

>>1424449
Ah, just found out that is a flyback transformer. Nice. I don't think the driver is there tho.

[Anonymous No.1424542]

>>1423560
>>1424407
I did it guys. Turns out it was the optocoupler (R38, like audio-anon mentioned). Or at least assume it is, because I'm getting a nice big signal before and a tiny one after. On the clean channel the signal is lower as well, but not a whole lot.

[Beppu !n/ZnkB9jUw No.1424547]

>>1424429
Because you can easily trim that type of wire. Easier than having to buy special fittings and a tool to crimp them every time you decide you want to rearrange your living room.

[Anonymous No.1424554]

>>1424547

I'd honestly rather just be given a long wire and then roll up the wire to the desired length.

is that the only reason?

[Anonymous No.1424582]

>>1424449
if you don't understand what that hose is or what it does you should absolutely stay the fuck away from it.
it can and will bite you

[Beppu !n/ZnkB9jUw No.1424588]

>>1424554
But then you have 6 giant coils of wire hanging off the back of the receiver because Sony doesn’t know if you’re trying to set it up in your backyard or tar paper shack.

What’s so difficult? I always fold the bare end of the wire over itself (I think my dad taught me that trick) and stick it in the little spring holder deal and I have never had a problem with a loose connection causing shitty sound.

Don’t fix what ain’t broken. Don’t be German and overcomplicate shit just so you can sell extra specialty tools to maintain it. Pic related, goddamn Germans.

[Anonymous No.1424614]

>>1424554
you are always free to crimp ferrules onto the ends of wires if you're so triggered about it

>>1424542
cheers, the scope found what the voltmeter could not
you might try removing the D27 half of the opto from the circuit (or tack a shorting wire across it, if that's easier) and seeing if the signal stays good. but I'm kinda suspecting the logic that drives it might be to blame, esp since I don't see a +5V supply source on the schematic anywhere and who knows how they're generating it

>>1424423
I suggest to stop at the first drop below 3V. some people discharge to first drop below 2.8V but you start to eat into the capacity below 3V

[Anonymous No.1424639]

>>1423438
>>1423399
I use the real deal at work and they are absolutely THE best for surface mount work when paired with their tweezers

[Anonymous No.1424644]

>>1424542
>>1424614
oops, derp, light makes the resistance smaller
you're right, probably time to just replace the optocouplers, if you don't want to remove the LED half from the circuit and give it 10mA in the right polarity with a resistor

[Anonymous No.1424680]

>>1424293
Hi Clive.

[Anonymous No.1424730]

[Anonymous No.1424747]

>>1424554
Higher end stereos have banana jack posts for you to either screw the wire onto, or you can crimp a banana jack onto it and jam it in

[Anonymous No.1424792]

>>1424747

maybe in the good old days. the fashion today is to use custom jacks and plugs, so that you wont be able to connect 100W speakers to a 120W receiver, even from the same manufacturer. and to lock you into buying their brand.

[Anonymous No.1424794]

>>1424792
>speakers and receiver from the same maker
Does not sound very high-end to me.

[Anonymous No.1424808]

https://www.aliexpress.com/item/microscope-to-find-my-benis/32884635847.html
is it garbage? should I spend the extra $40 on the famous ANDONSTAR 201?

[Anonymous No.1424809]

Anyone know a relay logic circut that shuts itself down?

[Anonymous No.1424811]

>>1424809
Like on a delay? Should be easy, just make yourself a truth table.

[Anonymous No.1424812]

>>1424811
on a codition. I'm too stupid to understand feedback and hysterisis. Like a circuit that cuts it's own power.

[Anonymous No.1424813]

>>1424812
determining the condition is up to you

[Anonymous No.1424814]

>>1424813
>>1424812
also feel free to add extra sets of contacts to the relays to control whatever thing it is you're trying to control, these are just the logic elements

[Anonymous No.1424909]

>>1424614
>esp since I don't see a +5V supply source on the schematic anywhere
Yeah, the schematic isn't perfect. Someone mentioned that it was for a prototype of the pedal. There's a 7805.
I'm going to need some more help though. Honestly I don't understand how this optocoupler stuff works, nor the switching stuff. With the diode test function on my multimeter I'm getting 1.55V across both LEDs, which seems fine. When the pedal is on I'm measuring 4,998V at the anode of both LEDs, so that's obviously fine as well. But then I've got 3,5V at the cathode of D6, and 0 at D27?

[Anonymous No.1424996]

>>1424909
>I've got 3,5V at the cathode of D6, and 0 at D27?

so, D6 is off and D27 is on. it's certainly possible to have them at diff states depending on the position of switch S1.

[Anonymous No.1425009]

Can I connect my car speaker wires to an RCA to 3.5mm adapter and then just plug in an mp3 player? Would it work?

[Anonymous No.1425011]

>>1424996
I've got 0V on that no matter what positions the switches are in.

[Anonymous No.1425015]

>>1424813
>>1424814

thanks my man, the logic part is all I needed. What software you used to draw that btw?

[Anonymous No.1425017]

>>1424293
>>1424108
Im not the clive you seek.

[Anonymous No.1425018]

>>1425017
But boy do I love lights

[Anonymous No.1425020]

>>1425018
And customizing them in any way possible.

[Anonymous No.1425035]

>>1424407
looks good anon, just a couple signals away from absolute zero

[Anonymous No.1425037]

>>1425035
Tfw I don't know what that's supposed to mean.

[Anonymous No.1425081]

>>1425020
dont it look funky

[Anonymous No.1425236]

>>1425015
KiCAD

>>1425011
when in the gain mode, what voltage across D27? how about R56?
if D27 and R56 have appreciable current through them while R38 is high-resistance, that LDR is definitely bad
if D27 and R56 have appreciable current through them whether in clean or lead mode, Q12 or whatever's feeding it is bad, in which case measure the gate and drain of Q12 in both clean and lead modes

[Anonymous No.1425242]

Building my collection of electronics components. What should I get? I already have plenty of ICs (the only thing I think I might need more of are 555 timers). Right now, the only thing I already know I want are some infrared LEDs (to make a TV remote).

All suggestions accepted.

[Anonymous No.1425243]

>>1425242
0402 SMD passives

[Anonymous No.1425250]

>>1425243
wtf is that

I am very new to electronics

[Anonymous No.1425324]

>>1425250
only kidding. if you're new you probably don't yet have the gear to deal in small surface-mounted devices
the usual and very good advice is to buy the stuff you'll need for what you expect to make. plan out a couple or three projects ahead, perhaps based on designs you see online that look manageable. instead of buying to build one, buy around ten of each item to build up your stock
for an IR remote type of thing, in addition to the IREDs, you'll probably want some microcontrollers, probably on a dev board like arduino/bluepill/D1-mini
if you're at all serious about the hobby, you'll probably want a good selection of "jellybeans", common components that you'll use in just about everything you build. you'd probably want a variety of 1/4W resistors (10 per value), a variety of ceramic caps (5-10 per value), a selection of electrolytic caps (5-10 or so per value <100µF, a couple each of bigger ones), ten or so each of the dozen or so most common transistors and MOSFETs, 10-20 each of a few different colors of LEDs, some LM358 op amps, maaaybe some DIP sockets for ICs you plan to use. aliexpress has a wide variety of component assortments that are suitable for a growing workbench
don't neglect tooling. if you don't have a good power supply, consider getting a 12V supply plus those little step-up and step-down converter boards that are literally all over aliexpress. they're not exactly a bench power supply, but they're usable and convenient

[Anonymous No.1425426]

>>1423156
Hello, I'm /g/, but /g/ is for consumerism not for technology.

How do I tell if a cable is sufficient enough to not burn my house? Like for example 20 to 24 atx adapter from China. It's not a "standard" part and it's hard to get, and /g/ is afraid of everything that doesn't have a big brand name slapped on it.

Also I have >FSPXXX-5DD01 pico-psu, but I know only that it's for 12v laptop adapter, but I can't figure out what wattage total it accepts (missing amperage). Finally, how do I figure out what (laptop) power supply won't fry it? I mean, these come only as - o +, right? so it's just jack size and amperage?

Sorry for a rambling post. I'm building a really small build and also I'm from a third world country, better stuff isn't sold here.

[Anonymous No.1425433]

>>1425426
the wires should have a gauge ("AWG") printed on them. refer to any online AWG current rating chart for the max current through any cable. their values are pretty conservative.

not all laptop bricks give 12v and you do need to check the polarity of the jack. it'll say so on the brick. you don't have to worry about it frying your board (unless the board wants to fry).

you're not likely to find a power rating for your supply.

[Anonymous No.1425437]

>>1425426
laptop PSUs vary widely in voltage. I haven't seen one yet that's only 12V, usually it's higher so it can fully charge 3 lithium-ion batteries in series with plenty of headroom. also, some laptop PSUs are "smart" and expect to communicate with the laptop, and won't give full power until they do (Dell...)
if you can get them, you might be better off using the power supplies intended for those LED strips, which are usually 12V @ lots of amperes. they're usually cheaper per watt than new laptop power supplies. I use one to power my workbench, my lighting, the fans in my server closet, ...

[Anonymous No.1425438]

>>1425433
How can I check polarity of the psu that is inside the computer the FSPXXX-5DD01? (so of the board that the jack goes into).

>it'll say so on the brick
I got the psu without any brick to supply it. I'm considering asking someone with more experience to solder a Chinese 12v "led" power supply to a jack and a power cable (make a laptop brick for me) but first I need to figure out polarity and max wattage of that board.

>the wires should have a gauge ("AWG") printed on them
Aliexpress doesn't provide details on stuff and if they do, then sellers would lie anyways.

[Anonymous No.1425441]

>>1425426
>How do I tell if a cable is sufficient enough to not burn my house?

it's actually super duper simple: you plug it in, let it run normally for 5 mins and grab it. is it cold, barely warm, slightly warm, warm, hot, too hot to hold? anything but the last two is acceptable.

>how do I figure out what (laptop) power supply won't fry it?

it's rated 12V so you apply 12V exactly, and it'll work.
current rating on the power supply just has to be able to deliver the needed watts. it doesnt matter if the amp rating is high. the computer will only take as much as it needs.

[Anonymous No.1425446]

>>1425441
>current rating on the power supply just has to be able to deliver the needed watts. it doesnt matter if the amp rating is high. the computer will only take as much as it needs.

So if I'll have a 12v20a power supply custom made for that pico-psu, it'll draw only as much as it needs from that laptop brick?

Finally, how do I figure out what polarity the psu has? It's not written anywhere on the PCB.

[Anonymous No.1425447]

>>1425438
>a Chinese 12v "led" power supply

bad idea. they're not designed to be particularly clean like a computer power supply. i regularly find 12V supplies at the thrift store from various gadgets at high amperages, most often Xbox power bricks. they cost around $5.

for polarity, almost everything is now standardized as PLUS on the center pin, MINUS on outer shell.

[Anonymous No.1425448]

>>1425446
>it'll draw only as much as it needs from that laptop brick?

that's the way all power supplies work. dunno why noobs think otherwise, coz it seems so logical.

[Anonymous No.1425451]

I'm confused, I'm new to electronics and I'm using a tantalum capacitor for the first time. I thought the marking meant negative? It even has a K next to the strip, it exploded into flames as soon as I powered the circuit. Can I get a quick rundown?

[Anonymous No.1425454]

>>1425451

yeah, tantalums are the exception. they made 'em specifically backwards to fuck with noobs.

[Anonymous No.1425455]

>>1425447
>i regularly find 12V supplies at the thrift store from various gadgets at high amperages, most often Xbox power bricks. they cost around $5.
I'm from a third world country. They wouldn't cost $5 and if they did it's still a lot of money. I'm already worried if the money I invested in that psu and small desktop computer parts isn't too much if there's a risk I might burn everything.

>>1425448
I'm worried that the draw from computer components might exceed the capability of the psu while the brick will be happy to deliver, resulting in fireworks.

[Anonymous No.1425456]

>>1425454
Would they explode on a 5v circuit (the one was 12v) or just not work? If it was working fine for an hour, would it eventually explode?

[Anonymous No.1425457]

>>1425456

you cant predict catastrophic failure. it will eventually leak, or break apart, or explode depending on many factors.

[Anonymous No.1425460]

>>1425455
>draw from computer components might exceed the capability of the psu

a properly designed circuit will do one of two things (1) put out the max current it can and no more, meaning the computer will fail to operate but everything will survive, or (2) shut down the power to the computer, and everything survives.

what a bad design will do is, of course, unknown.

you have to have balls to do this kind of work, or pay someone else to do it for you.

[Anonymous No.1425461]

>>1425446
it looks like the largest 5DD01 is 150W, so a 20A supply should be ample
"LED" supplies should be fine imho, especially if over-rated by 50%, and your mains power is clean. according to https://www.fspgroupusa.com/2013%20Industry%20Catalogue_V1.pdf it looks like the board reprocesses almost every voltage, and the 12V that passes thru gets reprocessed by the CPU power supply on the motherboard anyway
or, wait until you can accumulate $20 US and find a mains-powered supply that's a little less questionable

[Anonymous No.1425466]

I was reading all the posts carefully.

>>1425461
Thank you for you explanation.


>>1425460
>what a bad design will do is, of course, unknown.
It certainly can power a computer but I don't know how to judge a design quality. I just hope that if I'll connect one of the new less power hungry motherboards and cpus, It will not exceed the 120-150w.

I seen on youtube that there are small pico-psus power supplies that seem more reliable but these are not sold here and importing would probably be very very expensive adding postage and import tax and risk of it never arriving.

[Anonymous No.1425468]

>>1425466
you should get a hobby you can afford. what do the other third worlders do?

[Anonymous No.1425471]

>>1425457
Let me ask you this. If it was reversed, would the circuit still work?

[Anonymous No.1425478]

>>1425471

depends on the application. some caps are simply added to stabilize a voltage and are there JUST IN CASE they're needed. on the other hand, some have critical functions and the fact that the capacity is different depending on polarity, would make the circuit mis-behave a little or a lot.

[Anonymous No.1425482]

>>1425478
If it's the only capacitor on the board and it's reversed, I don't understand how it hasn't popped yet or how the circuit is working. It runs from 5v > 300ohm resistor then to the rest of the simple circuit.

[Anonymous No.1425483]

>>1425482
Wouldn't the circuit short and stop functioning once the 5v goes through the incorrect polarity capactior, thanks for your help.

[Anonymous No.1425484]

>>1425482
triple post fail

5v directly to 300ohm resistor directly to reversed polarity tantulum then to tl;dr video signals. Circuit seems to work fine?

[Anonymous No.1425493]

>>1425468
a popular hobby is migrating to white countries

[Anonymous No.1425541]

>>1425236
>when in the gain mode, what voltage across D27? how about R56?
I can't measure anything across either. Same goes for the clean channel ones though.
>measure the gate and drain of Q12 in both clean and lead modes
Seems like the schematic has drain and source swapped..? Drain is connected to ground. I've got 0V on source in both on and off state. Around 1V on the gate when on, and 9,8V when off.

[Anonymous No.1425681]

>>1425484

it sounds like the cap is being used as a bypass capacitor. here is definition according to google:
"The bypass capacitor is a capacitor that shorts AC signals to the ground in a way that any AC noise that's present on a DC signal is removed producing a much cleaner and pure DC signal."

so it's likely present in case the 5V supply is noisy. if the one you have is clean, then it's not needed and the circuit will work fine without it, or with it backwards. the other possibility is that the cap is not tantalum, and so it's polarity is correct.

[Anonymous No.1425718]

>>1425482
>If it's the only capacitor on the board and it's reversed, I don't understand how it hasn't popped yet or how the circuit is working.
low voltage through a resistor may have reformed it to suit polarity.

[Anonymous No.1425835]

[Anonymous No.1425840]

>>1425835
just use lead. metallurgists btfo.

[Anonymous No.1425862]

>>1425541
sources and drains are usually interchangeable on a JFET. also, the convention for current flow was established before we figured out electrons actually move in the opposite direction
my mistake, I meant D27 and R72
hmm, so Q12 isn't actually turning on? try shorting the drain and source (that area's all low power and high impedance, nothing will break if you do it right). if Q12 is bad, you get signal from the gain channel (is it mixed with the clean channel?) when this is shorted

>>1425840
>mmmm, paint grayons

[Anonymous No.1425889]

>>1425862
>hmm, so Q12 isn't actually turning on? try shorting the drain and source
Nothing changes when I do that, so I guess that rules out everything but the optocoupler? Was hoping it was something in the switching circuit, as axial optocouplers are apparently going out of style.

[Anonymous No.1425987]

>>1425889
to confirm, you could test the part out of the circuit (take care to mark polarity first). you'd need an ohmmeter on the highest setting (20Mohm?) and some way of lighting the LED (a 1k resistor and a 12V power supply, or a 750 ohm resistor and a 9V "transistor" battery). with no power, resistance should be well into the megohms (maybe higher than your meter can read). apply power, see if the resistance drops by a lot. if not, try reversing the power to the LED. if still no action, that's confirmation. if there is action, note resistances reinstall and there's still hunting to do

[Anonymous No.1426056]

I sketched this current limiter circuit for LEDs from a BD 136 power transistor, bunch of BC 547/-557, resistors and one diode.
I built a lower-current version of it on breadboard and it seems to work; it is short-circuit proof and the red LED lights up (and stays lit) whenever the transistors start to limit the load current.

How should I use the "Thyristor circuit" formed by Q201/Q202 to also switch off the main power transistor Q204?

[Anonymous No.1426062]

>>1426056
you could just stop pulling R215 down and thus shut the pass transistor off. not sure whether R216/Q206 would defeat it by feeding Q204's base from the output and keeping Q204 on

[Anonymous No.1426066]

>>1425835
Out of curiosity, has anyone here ever had troubles with tin pest? As far as I know it should be bloody rare, provided you're not using electronics in a deep freeze, in which case you should be using parts designed for such temperatures.

[Anonymous No.1426079]

>>1425426
Usually don't need a 20 to 24 pin cable, just leave the +4 empty, modern mobos don't really need it.

[Anonymous No.1426081]

>>1426056
You only need to change a single connection.

[Anonymous No.1426135]

what multimeter would you recommend for a complete beginner?
is there a difference between the 10€ ones and the more expensive ones?
i have a soldering iron already, should i get anything else?

[Anonymous No.1426141]

>>1426135
>what multimeter would you recommend for a complete beginner?
the aneng meter is highly regarded here but i haven't used it

>is there a difference between the 10€ ones and the more expensive ones?
yes but everything under $100 is garbage in its own way so there's no point in spending $50 rather than $10.

>i have a soldering iron already, should i get anything else?
a cheap power supply, hopefully with current limiting. you should only buy an oscilloscope, hot air gun, or usb microscope when you decide you need them. there's a lot of cheap odds and ends like tweezers or heat shrink that i can't be bothered to list.

[Kevin Van Dam !ZNBx60Gj/k No.1426142]

>>1426135
From somebody like 1 step ahead of you in attempting to learn what those things do, even the $10 ones give you a ton of the same readings and are accurate enough. I do like having the “Auto Ranging” feature which you can get on a lot of $20-$30 meters but not on the $10 ones. Also the backlight is nice if you’re working in the dark.

Pic related is auto ranging and super popular on Amazon. I have seen a couple anons with them and they never complain about them not wirking.

[Anonymous No.1426147]

>>1426141
>yes but everything under $100 is garbage in its own way so there's no point in spending $50 rather than $10.

this is just wrong. a $70 dollar meter is the same as a $10 dollar meter? Some other clown might as well chime in and say everything under $1000 is garbage in some way.

[Anonymous No.1426150]

>>1426141
>you should only buy an oscilloscope, hot air gun, or usb microscope when you decide you need them.

Anyone working with analog electronics should buy a scope as soon as they can afford one, whether they realize that they "need" one or not. Once they have used one, they will realize that they needed one.

I agree about the hot air gun and microscope; those are tools that lots of people will never need.

[Anonymous No.1426155]

>>1426147
autoranging, continuity testing, etc on "mid market" meters is universally terrible so what are you getting? a thermocouple? a voltage detector? fuck me if i'm paying $50 for that. i own a $60 extech and i'd just as soon grab my harbor freight special.

>>1426150
you're right, i just worry about telling someone brand new to spend good money on something that they might lose interest in a few months from now.

[Anonymous No.1426158]

>>1426155
>autoranging, continuity testing, etc on "mid market" meters is universally terrible
Werks for me :^)
Could be faster ofc, but would I rather not have these things? Nah.

[Anonymous No.1426161]

>>1426141
i have a chieftec aps-850c laying around, will that do?

>>1426142
>>1426155
so auto ranging yay or nay?

[Kevin Van Dam !ZNBx60Gj/k No.1426164]

>>1426155
There’s so many options on Amazon for $20-$40 that have all the features of a $100+ yellow thing but without paying for that exotic yellow pigment that costs $3,000 per gram that they use in Flukes.

The $40 meters on Amazon do a little more, at leasr are easier to use than the $6.99 HF special. And if somebody spends $35 on a DMM and loses interest in whatever hobby a month later, it’s only $35 and it will still come in handy diagnosing shit in the future. That’s the great thing about tools- it’s rarely a waste of money because there’s a good chance they will get you out of a jam years down the line.

[Kevin Van Dam !ZNBx60Gj/k No.1426166]

>>1426161
You don’t need auto ranging, it’s a convenience thing. Like the cheap meters have settings for 2V, 20v, 200V or whatever so you have to cycle through them manually to find the correct range sometimes. Auto-ranging has one setting for voltage and will figure where to put the decimal point for you.

The one thing my free HF was missing is continuity.

[Anonymous No.1426168]

>>1426161
>chieftec aps-850c
it will. it needs a bit of external circuitry to run so it can double as your first project. see the spam link and heed its warning in the 5th paragraph from the bottom.
www dot electronics-tutorials dot ws/blog/convert-atx-psu-to-bench-supply.html

you'll be missing out on nice features of a lab supply like variable voltage and current but nothing beats free.

[Anonymous No.1426170]

>>1426166
if you try 20v while it's set to 2v, will it explode spectacularly, show 2v, or somewhere around 20v?

[Kevin Van Dam !ZNBx60Gj/k No.1426173]

>>1426170
I believe it will just give you the OL reading.

[Anonymous No.1426272]

>>1426062
>>1426081
I tried throwing more transistors (Q207) to the problem but could not figure it out yet.
I feel like I'm doing this way too complicated. Any other hints?

[Anonymous No.1426287]

I made some changed and finally it works. Q207 now switches off power transistor's base current. And red LED notifies the user about the overload condition.

[Anonymous No.1426344]

>>1426081
>>1426287

[Anonymous No.1426386]

>>1425324
Thanks for the reply cutie. I already decided on buying an Arduino Uno (forgot to mention that). I don't know what projects I want to do, aside from the TV remote, but that's because I don't know what I'll be capable of doing or not.

A couple of extra questions:
- Why would I want different types of transistors/capacitors? Why not get just ceramic capacitors, for instance?

- What is an "LM358" good for?

- Why would I want DIP sockets if I can just put my ICs in a breadboard already?

- What's a step-up/step-down converter board good for?

Please don't laugh too hard, it's been years since I took a digital systems course. Also, when you say that I'll want several resistors, capacitors, etc per value, what should be the "step" of the values? e.g. 10 1W resistors, 10 2W resistors, ..., or 10 1W resistors, 10 1.1W resistors, ...?

[Anonymous No.1426395]

>>1426386
>Why would I want different types of transistors/capacitors? Why not get just ceramic capacitors, for instance?
ceramics are more "ideal" capacitors but they're less dense so they're not practical for large capacitances. electrolytics are shitty but can have large values. regarding transistors, you need npn bipolars, pnp bipolars, and nmos mosfets. these are very different devices and aren't often interchangeable, despite all fundamentally just being switches.

>LM358
it's an "operational amplifier". it can take a weak signal (low voltage, high source impedance) and make it strong, as well as a fuck ton of other things. op amps are fundamental building blocks.

>Why would I want DIP sockets if I can just put my ICs in a breadboard already?
you don't really need them, but if you're making a perfboard or anything other than a breadboard they can let you debug easier or salvage pricier chips like microcontrollers.

>What's a step-up/step-down converter board good for?
in electronics you commonly need a lot of different voltages. you can live with just +12 and +5 from an atx psu but it'll be pretty annoying.

[Anonymous No.1426539]

>>1426395
So DIP sockets are basically just little houses for your IC spiders to live in and be protected when you're soldering/unsoldering them a lot?

Thanks for the other answers. I also found this guide http://blog.thelifeofkenneth.com/2011/06/so-you-want-to-build-electronics.html, is it any good? It seems to agree with what >>1425324 said.

[Anonymous No.1426549]

>>1426386
>step of the values
there are standard series, e.g. E24 which divides an order of magnitude into 24 somewhat evenly spaced values. usually you only need such precision for resistors, and then only if you're doing much analog stuff. as a microcontroller user, you probably won't need a full complement, at least at first, and 1/4W will be perfectly adequate for most anything you would do. this is a good starter kit for a microcontroller user https://www.aliexpress.com/item/ow-my-butt-hurts/32475181535.html
>don't know what I'll be capable of doing
read, read, read, read, read. pause to parse, and then read a bit more. if there's one good thing about arduino projects it's that they're copiously documented and you can usually puzzle your way through them

>>1426395
>fundamentally just switches
I prefer the term "current sources"

>>1426287
but does Q207 stay on even when the fault is removed? also, 1mA isn't much current to light an LED
I was thinking, in relation to v4, to run the right leg of R227 to Q201 collector instead

>>1426539
think of them as less permanent connections, like mains outlets vs. hard-wiring

[Anonymous No.1426560]

>>1426549
Are these series (E24, 1/4W, ...) standardised? I can't really find what I'm looking for when I google for 1/4W resistor.

Also, 2 other questions:

- >>1426395 said I would need different types of transistors, but I don't understand why he said they weren't interchangeable. I understood the part about capacitors (ceramic = low capacitance, high accuracy // electrolytics = high capacitance, low accuracy), but they would still be interchangeable if I didn't care about accuracy and happened to have 2 different types of capacitors with the same capacitance. Is this not the case when it comes to transistors?

- Would making a shitty radio be a viable project for someone as new as me? I don't want to do the sort of project where I'm just following recipes, ideally I'd be doing projects where I know what I want to do and have the ability to do it myself out of the building blocks I have (like programming).

[Anonymous No.1426565]

>>1426560
Ok, I semi-answered my first question: E24 is a standardised series, and you just apply it to different components. I still don't understand the 1/4W terminology though.

[Anonymous No.1426567]

>>1426560
for a radio you will need inductors, you can buy them or make them
"the art of electronics" has instructions for a shitty radio in the chapter about filters or oscillators

[Anonymous No.1426574]

>>1426565
>I still don't understand the 1/4W terminology though.
resistors have 2 values: resistance and max power

the resistance is measured in ohms (or kohms, or Mohms) and it is how much it resists against current flowing through it (ohm law)

the max power is a rating of how much power it can safely dissipate, larger resistors can dissipate more power
P = I^2 * R
P = V^2 / R

So, if you have a 1 kohm resistor rated for 1/4 w, it can safely sustain a current of I = sqrt(0.25 / 1000) = 0.016 A = 16 mA

[Anonymous No.1426581]

>>1426574
Oh, so 1/4W is literally just 0.25 watts. I get it now. I thought >>1426549 was telling me to get a series of resistors called 1/4W (with some fixed step), not a series of resistors that could handle 1/4W.

Last question I can think of for now: how would you tell a resistor's wattage by looking at it? For the resistance you have the colour codes/ohmmeters, but what about maximum wattage?

[Anonymous No.1426589]

>>1426581
>how would you tell a resistor's wattage by looking at it?
As far as I know, you don't, when you buy them they say what is their power rating
if you take them out of some scrap board, you'll have to guess (1/4w seems to be very common, bigger, fatter resistors should be higher power)

[Anonymous No.1426643]

>>1426581
Each "package", the standardised dimensions the components are made to, will have a maximum temperature rating (in °C or K) and a thermal resistance to air (in K/W). By taking the difference between the maximum temperature and the air temperature and dividing this by the thermal resistance in air, you'll obtain the maximum power rating. This applies not only to resistors but to all packages from ICs to transistors to inductors, and you'll find values on each packages' datasheets that tell you their thermal resistance to their top or bottom for connecting to heat sinks/PCBs if these apply. Any heat sinks you buy (and thermal pads/heat sink compound) should also give a thermal resistance value.

All you have to do is measure the dimensions of an unknown package and search for a similar package online, but it should be easy to search instead for "0.25W resistor dimensions" for something along the lines of pic related. This one's off aliexpress so take it with a cube of salt.

[Anonymous No.1426662]

>>1426589
>wattage

[Anonymous No.1426697]

>>1426560
transistors are more complex than that. there are a few dozen general forms of transistor, which are not drop-in interchangeable, and each of the thousands of types of each are optimized for certain parameters at various trade-offs with others. for example, package size, max collector/drain current, speed, current gain/transconductance, max voltage, and of course cost. you would need to lightly analyze the circuit to determine whether it would still work with a substitute transistor
fortunately, for non-critical applications and most experimentation, one can usually get by quite well with a limited cross-section of the thousands of types available: a small-signal NMOS, a power NMOS, a couple or three small-signal switching npns (and pnps to complement them), maybe a power pnp and a power npn, and a power PMOS if you really want to get fancy
I recommend: BS170, FQP30N06, PN2222, PN2907, 2N3904, 2N3906, MPSA42, MPSA92, TIP31, TIP32, FQP27P06
in the event of a special need, you can of course buy a special transistor to fill it

[Anonymous No.1426714]

Just took apart an old smoke alarm, found it doesn't have two ion chambers but rather a single one and a built-in reference for use with its comparator. (If they have two only one is open to the air to get a comparison value from the other to determine when to trigger the alarm). I was hoping to remove one of the ion chambers and use it as a standalone radiation detector to use alongside the geiger counter I've not yet built for some rudimentary testing and comparisons, as well as using the americium as a radiation source to test with. Unfortunately the americium is built in to the sole ion chamber, so I can't really use it as a standalone detector for anything except establishing a benchmark against the americium source. It's wrapped in foil at the moment and I'm not stupid enough to try to pry the two apart and create americium dust.

I might take the americium in to uni tomorrow and use a geiger counter they've left out to measure its activity. I'll also see about turning the source+chamber into something I can get observable counts from, since the original circuitry that was present has its comparators, timers and audio oscillators built in. It might be possible to circuit-bend a smoke alarm into a radiation detector if you remove the americium, tune the alarm timer to <1ms, and "invert" the buzzer signal, but I'll not try that unless I get an external ion chamber.

>>1426697
The TIP31 is ass.

[Anonymous No.1426734]

>>1426697
I'd add a pair of Darlington transistors to the list. They are often useful.
BD681 + pnp equivalent.

[Anonymous No.1426735]

>>1426662
>voltage
>amperage
>ohmage
>watts???
it's wattage

[Anonymous No.1426744]

>>1426735
>voltage
Only autistic people say anything else, but potential is technically more correct.
>amperage
If you're a welder and you don't know any better, but the correct term is current.
>ohmage
The actual term is resistance and you have brain problems.

[Anonymous No.1426770]

>>1426744
>Only autistic people say anything else

only autistic people engage in these kind of nugatory discussions.

[Anonymous No.1426774]

>>1426744
>If you're a welder and you don't know any better, but the correct term is current.
How many currents should I use for 3/16" E7018 DCEP?

[Anonymous No.1426778]

should i start with embedded or do electronics first

[Anonymous No.1426804]

Forgive me if this is a stupid question. But can't you use a DC power supply like the one in the picture as a means to charge batteries?

Say for example I have a NiMH battery that charges at 12V 0.5A. Can I not just set the DC power supply to those values and connect to the battery with crocodile clamps?

Why even bother with individual power banks with preset values?

[Anonymous No.1426811]

>>1426734
when have you actually needed one tho?

>>1426804
sure, if you don't mind overcharging it and shortening its life, you could do just that
I suggest you read up on the individual battery chemistries and their recommended (and disrecommended) charging algorithms. voltage @ current is a grossly oversimplified charging profile

[Anonymous No.1426836]

So I want to use raspberry pi GPIO, but i have trouble understanding difference between input and output.

It seems to me that the only difference is that as output it generates 3V or 0V and as input it RECIEVES 3v or 0v, but then what is the purpose of pull up and pull down mode in the input? input always needs to be pulled down when the foreign 3V from some device stops

[Anonymous No.1426847]

>>1426836
>i have trouble understanding difference between input and output.
pic related

>It seems to me that the only difference is that as output it generates 3V or 0V and as input it RECIEVES 3v or 0v
when in input mode the pin has a high impedance, but before this impedance there can be a pullup/pulldown connection, this acts a "default" state for the pin if it is disconnected (so it doesnt float), you use that with buttons

[Anonymous No.1426852]

>>1426847
But why does connecting 3V to the pin and setting it to output instantly destroys that pin forever?

[Anonymous No.1426867]

>>1426852
When the pin is in OUTPUT it can be HIGH (connected to 3v3) or LOW (connected to ground).
In either state it as low impedance, as opposed to INPUT.
If you connect 3v to an OUTPUT pin on LOW state, you have a short to ground because of the low impedance, this causes a high current that fucks the transistors or whatever.

[Anonymous No.1426891]

>>1426867
So if the pin is in input mode it should be save to short the 3V3 rail to the pin right?

[Anonymous No.1426910]

>>1426891
Yes, because the high impedance means low current.

[Anonymous No.1426984]

>>1426589
>>1426643
>>1426697
>>1426734
Thanks for everything, cuties.

>>1426744
What's your problemage?

[Anonymous No.1427018]

What happens when I add a single capacitation into a circuit in series? Will it allow current flow until it charges?

[Anonymous No.1427019]

>>1426804

dont listen to that negative nancy, current-limited lab supplies are great for charging nicads and nimhs. even lipos if you have an intelligent supply. i've been using my lab supply for 15 years this way, coz i have so many gadgets, it would be insane to have individual chargers for each one.

once the batteries are full, they tend to get warm (or hot) so i do one of two things, (1) charge at low current, say 0.2 times the rated ampere-hours, or (2) use a meat thermometer with an alarm function to warn me when they get above 50-deg C.

[Anonymous No.1427020]

>>1427018

google that shit, nigger.

[Anonymous No.1427023]

>>1426744
voltage literally means electrical potential.
saying "potential is technically more correct" is industrial-grade autistic nitpickery.

[Anonymous No.1427025]

>>1423156
It's been so long since i studied ohms law I forget how to calculate it but answer me this: if a teensy 2.0 has a pin set to input_pullup, how many mA does the 10k? internal pullup draw on 5v and 3v, with a regulator soldered underneath.

[Anonymous No.1427031]

>>1427025
depends what the pin is connected to. if it's left unconnecting the only current draw is the pin leakage, which is a uc datasheet spec (and a very imprecise one at that)

[Anonymous No.1427033]

>>1427031
in this case the pin is connected to ground and used as a switch.

[Anonymous No.1427034]

>>1426549
>run the right leg of R227 to Q201 collector instead
That's a great idea. I tried it; works great. Thanks a lot.

[Anonymous No.1427035]

>>1427033
is it connected to ground through the switch? if it's hard connected to ground then it'd draw (5V,3V)/10kohm=500uA or 300uA.

[Anonymous No.1427037]

>>1427035
perfect thanks.

[Anonymous No.1427041]

>>1427034
That's a rather iffy idea, as pulling enough current from that node makes the "scr" trigger.

[Anonymous No.1427045]

>>1425987
Thanks for your help, anon. I swapped it out with the clean channel one and it works now, so I just need to find a suitable replacement.
It's a NSL 37v31, but I can't find a datasheet on it. It's run at 3 mA and I measured the on-resistance to 440 ohm. Didn't bother measuring the bad one. Allegedly the vtl 5c9 is compatible, but it has lower on-resistance than what I measured. Not sure how much that matters in this circuit? It's also retardedly expensive at more than $10 + shipping because it's out of production. A german shop wants €17.

[Anonymous No.1427068]

Any ways to add a delay to a led? i need the thing to turn on about half a sec after power is applied and stay on for for half a sec as well after the power turned off. it also needs to be small

[Anonymous No.1427069]

>>1427068
capacitors

[Anonymous No.1427107]

how do you design power supplies for custom electronic circuits

everything commercial uses 5, 9, or 12 volts meanwhile if I do the math on my circuits I wind up with weird values like 8.5, 11, 7, 6, and so on. How do I make this work? Adding resistors or voltage regulators seems like a waste of battery life

[Anonymous No.1427111]

>>1427107
>meanwhile if I do the math on my circuits I wind up with weird values like 8.5, 11, 7, 6,

I hate when that happens.

[Anonymous No.1427131]

Any idea why my instrumentation amplifiers decide to fuck with me when the input signal is switching polarities?

I'm using a H-bridge driver (square wave) to drive a coil and am measuring current and voltage signals over it (pic related only shows current measurement)

I have no idea why this happens. Any guesses?
If I put a resistor instead of a coil everathing is fine, the output is a square too

[Anonymous No.1427132]

>>1427131
>If I put a resistor instead of a coil everathing is fine, the output is a square too

I'm a noob too but I think this might be a clue.

[Anonymous No.1427136]

>Me: Brit who has had 5-second powercut recently that messed with PC
>Have surge protection because not retarded, but nothing against short outages
>Remember there's a UPS that nobody's paying attention to at workplace (second-hand shop/thrift store)
>Get hold of it
>Turns out the brand is Polish, and it's got a schuko plug with a UK adaptor stuck on it
>fug
Can you buy a third pin for connecting the earths of the plug and the socket? Or am I stuck being paranoid about having no earth?

[Anonymous No.1427208]

>>1427136
Just put a UK plug on it?

[Anonymous No.1427210]

>>1427136
Or do you mean the socket? Really not sure what's what here. Just get a 3 pin adaptor, or replace plugs - whichever is relevant to you.

[Anonymous No.1427240]

I've been soldering with rosin like... Forever. But I've moved to other country, where I can't buy rosin.
I've tried plumbing flux - too conductive and corrosive.
Recommend me fluxes, pls.

[Anonymous No.1427245]

>>1426770
I didn't say I wasn't autistic.

>>1426774
I'm not a welder. Also it's "how much current", you illiterate coat-hanger.

>>1427023
Yes.

>>1427131
I'm not sure how well ICs handle reactive loads. Perhaps adding some sort of push-pull transistor buffer would help. The IC probably just has a single transistor to control its output, which might explain why it's only hitting a problem when going down through 0V and not up. Measure current as well with another scope channel, it might give you some insight.

>>1427240
No-clean flux.

[Anonymous No.1427253]

>>1423156
Dodgy lamp you say?

[Anonymous No.1427257]

>>1427253
That a toaster?

[Anonymous No.1427258]

>>1427245
>No-clean flux.
Can you give links or brands?

[Anonymous No.1427259]

>>1427257
Ion pump.

[Anonymous No.1427264]

>>1425448
Some devices actually depend on the power supply to limit current or they'll pull too much and end up burning themselves out.
Particularly older stuff, like the Apple fucking Lisa.

[Anonymous No.1427280]

>>1427025
in fact, it's about 50k, and so E=IR and remember your algebra

>>1427045
lower on-resistance is no problem at all, the impedance from the source is hundreds of kohms. off-resistance must still be in the tens of megohms or higher
>3mA
you sure? from the schematic it looks more like 12mA, but you can easily replace R72 with 3.9kohms to make that so
>retardedly expensive
das stimmt, they're boutique items now, much like vacuum tubes

>>1427107
in volume, you just call up the manufacturer and say "I can haz" and they quote you. not that these are 100% fficient either
in less than volume, switchers are pretty efficient. most good datasheets offer detailed component sizing and selection guides

>>1427131
your inputs are almost certainly going outside the rails. try adding some voltage dividers/input resistance to the ina to keep its inputs within the rails, and maybe a ±12V supply for the ina

>>1427240
hm, start reading safety data sheets for fluxes and see if you can get the appropriate constituents. glutaric acid is an ingredient in some no-clean fluxes

>>1427253
very dodgy
t.brent rambo

[Anonymous No.1427334]

>>1423156
I have a pair of Skullcandy headphones here that the right earpiece suddenly stopped working in. I assumed that the wire just came loose, so I opened them up. The wire appears fine. I opened the left earpiece to see if it looked the same and it appears the same to me. What should I do? Should I just resolder the wires on the right earpiece? I was thinking maybe the connection in the plug is broke, but I don't know what part corresponds to what on the plug to the earpieces. It has a button on the side on the side of the left ear piece, but it is only a skip button.

[Anonymous No.1427336]

I have a question related to headphones - one side stops working due to fucked 3.5mm jack or wire that connects to it (it works only at cetain angles). I get it replaced by an electronics repair service and afterwards the frequency response or outright gain (or both) is different on separate sides.
When my other pair did the same thing, i went to a really high end repair shop and said that price doesn't matter, but i needed a good repair. They said i shouldn't worry, but the same fucking thing happened, though they didn't charge much.

Why? Is it a resistance caused by solder amount? Can this shit be avoided? I remember doing the same thing in my father's workshop as a kid, and it worked fine, but now i'm at uni and can't do it. It's really important to me since i produce music and while gain problem can be tweaked, mixing a track is a nightmare with problems like different frequency response.

>inb4 buy new headphones
I got these high end phillips ones as a gift, but am a poorfag

[Anonymous No.1427341]

>>1427334
Not sure it will help, but I just found that the button is Android compatible and these also have a built-in mic. Still trying to figure out that jack.

[Anonymous No.1427342]

>>1427341
OK I found a diagram. How do I use my multimeter to test to see what is broke?

[Anonymous No.1427377]

>>1427280
>off-resistance must still be in the tens of megohms or higher
Alright. That's no problem.
>you sure? from the schematic it looks more like 12mA, but you can easily replace R72 with 3.9kohms to make that so
Yeah. It's actually 5V and not 12. If I could run it at 20 mA I could just use a 5c1 which is cheap af.
>they're boutique items now
Hmm.. Seems like the people who are interested in these kinds of optocouplers are mostly building compressors, so I think they may actually want them for their electrical peoperties. Or they're just trying to fix shit like me.

[Anonymous No.1427420]

>>1427377
>the schematic is just an artist's impression
kek
>5c1 which is cheap af
5c8 also look alright, even the 5c1 if you gave it about twice the current, which that FET should be able to supply. R37 and R45 being large (parallel to 200kohm or so), a couple more % of R(on) won't mean shit
see also http pdf datasheetcatalog com/datasheet/perkinelmer/VT500.pdf

[Anonymous No.1427428]

>>1427342
Never used it before to check continuity?

[Anonymous No.1427429]

>>1427428
A long time ago. Mine doesn't get much use.

[Anonymous No.1427434]

>>1427429
First you connect the test leads and switch it on. Select the continuity/smallest resistance function. Then you connect both tips and note the displayed value. This is your zero for later reference. Next you check both (!) headphone systems directly at their solder joints. Both should show (almost) the same resistance. Then you check the wires that lead to the plug. If your diagram is the right one (there are two different wiring schemes) it tells you what should be connected. It helps if you log the results.

[Anonymous No.1427445]

>>1427334
Those use the CTIA / AHJ standard, the pinout should be [left, right, ground, mic] from tip to sleeve. Chances are the jack itself has gone internally, you can either try carefully peeling away the rubber around it, trimming and resoldering the wires, and coating the thing in epoxy/hot-glue/silastic/etc. or just replacing it with another one. Using hot glue/etc. on a replacement plug is also an option as it will help with strain relief.

>>1427342
That diagram doesn't look right, the terminals should be like concentric cylinders, so the blue "left" conductor should be both the right-most solder terminal on that diagram.

>>1427336
That sounds very unusual. I'd go to the shop and tell them they did a shitty job.

[Anonymous No.1427471]

So, I have a circuit with some sensitive electronics that can't handle any extra current. Will adding inductor protect my shit from things like lightning strikes which can raise the voltage from 5V to 5M V for a short moment?
It should right, since the inductor resists current changes?

[Anonymous No.1427479]

>>1427471
not very well. inductors are also slightly capacitive, between the windings. you should instead use a shunt technology like TVS diodes, MOVs and/or gas discharge tubes

[Anonymous No.1427502]

I noticed i connected a capacitator backwards, the capacitator is rated for 25V and i fed in 3V, was than low enough to not brick it? i see no smoke or bulging

[Anonymous No.1427507]

FUCK why isn't this working?
both resistors are 1k ohms,
the capacitator is 1uF since i didn't have anything smaller
yellow line is 3V
orange wire is input pin which waits for voltage to go over 2.6V in order to read logical 1
and blue wire is ground

the theory is simple, the current flows and voltage drops directly from yellow line to the ground through the capacitator
the voltage on the logical pin is at this point too small so it reads as low (or zero)
when the capacitator charges, the resistance will become too high for current to flow, and the voltage on the logical orange pin rises high enough to read 1

I have a python script running which counts or loop cycles it takes for the capacitator to charge before the logical pin reads 1 and then it outputs the amount of loop cycles (python's while)

The problem is that it always outputs 1, which is stupid because there is no way the capacitator charges itself fast enough to rase the voltage on the logical pin so fast

So what is going on?
Is it because i don't have the 220nF capacitator and am using 1uF instead? But that is only like 5 times bigger so it should be fine and should actually take even more time to charge. So how the fuck is the logical pin getting over 2.6V on it instantly?

[Anonymous No.1427536]

>>1427507

if the pot is at minimum, the the time constant is roughly 1 millisecond (from 1K and 1uF). so maybe your timer cant catch anything that fast.

this is one of 1 million possible scenarios. it's by working through them on your own that you gain expertise; so get going.

[Anonymous No.1427537]

>>1427536
Already managed to figure it out.

It was a typo in the pythong code


fucking one missing space

should be
return
instead of
return

[Anonymous No.1427543]

>>1427537

ahaha, interpreters that dont catch syntax errors. welcome to 1980.

[Anonymous No.1427545]

>>1427543
No IDE with catch a typo that isn't a syntax error.
The bug was a perfectly valid syntax where the return was a part of the loop, while without the space it was executed only after the loop.

[Anonymous No.1427756]

>>1427136
if the schuko has no earth then its designed to not need an earth i guess?
surprised its not a replaceable iec lead

[Anonymous No.1427809]

I asked this in a thread a while ago, but forgot to come back and check,so sorry if this sounds familiar:
Good books on analog circuit design? Maybe it has some common circuits, their uses, and a little bit of analysis? I had an interview a while back with an instrumentation company and it made me realize how little I know about analog stuff beyond amplifiers.

[Anonymous No.1427820]

>>1427136
which part of the plastic case do you want to 'ground'?

[Anonymous No.1428008]

>>1427820
passing earth through the UPS to the protected devices is wise
except for those polack UPSes that just backfeed into the mains

[Anonymous No.1428028]

>>1427253
Where did you get that T section?

[Anonymous No.1428049]

How long does it take for a 1uF capacitator to charge through a 1K resistor at 3.3V? And how long to discharge?

[Anonymous No.1428066]

>>1428049
See >>1427020

[Anonymous No.1428076]

>>1428049
>I = C*dV/dt
Where V = voltage across capacitor. Do the differential equation.

[Anonymous No.1428100]

>>1428076
Meh i'll just eyeball that shit, math is gay

[Anonymous No.1428107]

>>1428100
in R*C seconds, your C will be charged to 63.2% (or was it 62.3%?) of the voltage on the other side of the R
gloogle RC time constant, nigger

[Anonymous No.1428113]

>>1424730

[Anonymous No.1428119]

>>1428107

he said he couldn't do math.

[Anonymous No.1428129]

>>1427756
Schuko does have a ground, uses clip/spring contacts on the sides. You can fit the schuko plug into some other kinds of sockets that don't have the proper ground contacts though.

[Anonymous No.1428194]

So I've recently bought new earphones, but when I use them with my ipod touch, sometimes the music will stutter a bit, play at a higher volume for < half a second and then return to normal. It happens seemingly at random, at least I haven't found a way to trigger it. I've never experienced this with my old earphones.
The only difference I can tell is that the new ones have a mic and a button, whereas the old ones were plain TRS. I've also tried setting a max volume on the ipod, which resulted in only stuttering without the volume bump.
Is it possible that the mic can somehow make the device think that volume- or other control buttons on the earphones have been pressed? It's the best guess I could come up with.
Apple uses CTIA/AHJ I think, but I couldn't figure out how the playback control works exactly.

[Anonymous No.1428224]

>>1428194
absolutely possible

>>1428119
in which case he needs to gtfo and pick a hobby more suited to his abilities

[Anonymous No.1428228]

>>1428224
>absolutely possible
thanks. Is there a way to make a TRRS plug appear like a TRS plug to the device it's plugged into?
The inside of the mic case looks like this:
wire 1 ---------------------------------- speaker wire
wire 2 ---<|.play/pause- |>---/ mic \
wire 3 ---<|.button.........|>---\ /
wire 4 ---------------------------------- other speaker wire
seems like the button shorts wire 2 and wire 3, which I assume are ground and mic. Could I just short those permanently? The mic has two terminals labelled + and C, could I replace it by some other part that makes it look like a mic that doesn't change? I don't need the playback control, so I don't mind if it doesn't work afterwards.

[Anonymous No.1428235]

>>1428228
I'v managed to replicate similar behaviour by touching some unisolated wires together in the mic case, so I'm pretty sure that's the source of the problem

[Anonymous No.1428251]

>>1428224
>in which case he needs to gtfo

I really don't like the snobbish attitude on this general. When Edison or whoever was inventing capacitors do you think he stopped to check everything with math? All the original work was done by the seat of the pants.

[Anonymous No.1428262]

>>1428228
if you can't triforce, post images
anyway, I think you want to short the second ring (from the tip) and the sleeve, whatever that works out to inside the little case. that would be electrically equivalent to a plain, old-school TRS headphone plug. so wire 2 and wire 3

>>1428251
4/8, git gud or go back

[Anonymous No.1428268]

>>1428262
yeah I decided to go ahead and short mic and gnd and put a little isolation around them. The headphones still work, I'll see if the glitches disappeared tomorrow.

[Anonymous No.1428365]

>>1428251
>compares himself with edison
>but we're the snobs
Fucking niggers

[Anonymous No.1428372]

>>1428251
>When Edison or whoever was inventing capacitors

>edison
>capacitors

[Anonymous No.1428381]

>>1428251
>Edison
>inventing

[Anonymous No.1428420]

>>1428381
this
Edison was a salesman and promoter
He bought other peoples inventions and had employees improve them - INCLUDING THE FUCKIN LIGHT BULB
Tesla worked for him for a while but Edison reneged on a promise (surprise) and Tesla went his own way.

[Anonymous No.1428425]

I have an SMPS, that is supposed to give 24V on output, but it gives only 4-8V.
I've changed TL431, all caps... Doesn't chooch.
Voltage is unstable as a fuck.

What do?

[Anonymous No.1428458]

>>1424730
Rolling

[Anonymous No.1428460]

>>1428228
One wire is ground, one is left, and one is right, so you've only got one wire with the buttons and such on it (the sleeve). The centre button is just shorting this microphone wire to ground, while the volume buttons short to ground via a resistor. It is possible that the mic is receiving enough of a signal that it drags the voltage (~2.5V through a few kΩ pull-up) down enough to make a volume change, but then always having it change back again, not to mention the added glitchiness makes me think the problem is with the iPod itself. I know my iPhone has been giving me glitchy audio lately, though without the volume changes (my headphones don't have volume buttons).

>>1428251
I think you should be talking about Michael Faraday instead, he was all about magnetic experimentation but couldn't do math to save himself. Everyone talks about how he discovered induction and all that, but the unit named after him is for capacitance. Lenz BTFO.

[Anonymous No.1428502]

>>1428460
This isn't the 1800s anymore where you're doing shit in unknown waters. We know the math behind this shit. If you're unwilling to use even a bit of math, then yes, that anon is correct in saying perhaps you're involved with the wrong fucking hobby

[Anonymous No.1428509]

What happens if you try charging your phone with an ac source? Will it get charge/discharged/charge/discharged?

[Anonymous No.1428510]

>>1428420
>promise

>boss say "Ill give you a million dollars if you fix this"
>autist thinks thats a bonding contract

[Anonymous No.1428518]

>>1428509
You'll kill the phone.

[Anonymous No.1428522]

>>1427809
Sedra/Smith for basics of circuit design. You can find the book + solutions manual on chegg.

[Anonymous No.1428523]

>>1428522
Whoops. Not chegg. On libgen. Someone took the answers from chegg and uploaded it to libgen

[Anonymous No.1428527]

>>1428502
No I wasn't arguing either side of that point, just noting that he picked the wrong dude to talk about. I was the guy who suggested he do the differential equation in the first place.

[Anonymous No.1428529]

>>1428518
Why?

[Anonymous No.1428532]

>>1428529
it's not meant for negative input

[Anonymous No.1428533]

>>1428529
Phone batteries require a very careful method of charging, putting in the right amount of current at the right time. By whacking it up to an AC source you'll not do that and probably ruin the battery. If you use a low-current source up to a big enough battery by itself then it will probably just oscillate a little as you said, but to make matters worse phones have a bunch of battery control circuitry already inside them. Meaning you'll probably put a negative current through a reverse protection diode and fry the thing.

>inb4 they should be called "phone cells"

[Anonymous No.1428556]

>>1428527
Fair enough - my mistake anon
The Faraday is a better role model yes, but I doubt that the anon was willing to keep meticulous records and descriptions on what was going on, and would actually just tinker blindly with no method to his approach

[Anonymous No.1428576]

>>1428028
Same place I got the Ion Pump.
The T-section was actually part of an Ion Gauge, but I couldn't implement the internals into the design, so I pitched it (too delicate to be functional). My next lamp will be much, much bigger.

[Anonymous No.1428582]

>>1428425
Well, it was a cracked trace. I fixed it with waking with hammer. Like old TV.

[Anonymous No.1428602]

>>1428582
>I fixed it with waking with hammer
Welcome to the board, Red.

[Anonymous No.1428624]

>>1428576
i want to fill those flanges with bolts

[Anonymous No.1428650]

>>1428576
What does the lamp's ion pump actually do? Does it evacuate the bulb itself?

[Anonymous No.1428668]

>>1423156
Nice flashlight bro.

[Anonymous No.1428744]

>>1428510
edison was a retard tho
>have an employee who is clearly a genius
>fuck him out of what is pocket change to you causing him to quit instead of givinng him a raise and shit so he can use his genius to make you trillions
fucking dumbass cracker edison

[Anonymous No.1428757]

>>1423190
>I had to add a delay of 200us to get it to not spit out garbage.

sounds like it's noise on the wire?
twist the cable, keep it as short as possible.
i2c is not as nice as you would like it to be.

ads1015 may have a upper limit of sampling rate, read the datasheet carefully.

(I am unsure:)
Maybe the Arduino are too slow for you?
Maybe you'll need to change ADS1015 to something else?
Maybe your circuit solution could be improved?
Not enought caps? (to keep the noise down)
Maybe you don't have enought or dirty power?
AD1015 may be heating up, so it'll be unstable.
You could also have ESD-issues, just to fuck you up! :)

Do not begin to solve problems with software, debug FIRST the hardware, be asbolute sure that everyting is okay. It's often small and stupid things that breaks everything else!
Then fix errors in the software. Your code (and later solutions) will be cleaner.

[Anonymous No.1428762]

>>1425451
>using a tantalum capacitor

run for your life!
I hates tantalum capacitor, they seems too fragile, an electonic caps do the job much better. Why do they exist?

They even short circuits when they're dying, and that's the reason I really hate them. I was fooled into buying some to a project, and later discovered how scarey they are. Very nice for companies who wants to save some dimes and restrict the lifelenght of their products.

[Anonymous No.1428767]

>>1428757
>Maybe the Arduino are too slow for you?

commenting/correcting myself:
Arduino is coded to 100Khz, can be changed to 400Khz. The ADS1015 can do 3.4Mhz.
Rise time on the ADS1015 should be a least 160ns.

[Anonymous No.1428770]

>>1428762
>why Ta
before ceramic caps could be made in the larger capacitance values necessary to handle the current demands of serious digital ICs with simultaneously switching outputs, Ta caps were the most reasonable way to get the low ESR necessary to brace the supply rails robustly enough
>restrict the lifelength
>implying electrolytics don't
hmmmmm

>>1428767
what are your I2C pullup values?

[Anonymous No.1428776]

If I plug a high-order high-pass filter to my mains, can I listen to audio frequencies or demodulate RF?

[Anonymous No.1428778]

>>1428776
why not, it's what X10, HomePlug, etc. do, more or less
(except they use signal transformers)

[Anonymous No.1428785]

>>1428778
It's more wondering if there'd be any useful signal around. I'd probably want to ensure I miss any PWM buzz also, I wonder if you'd get that up near 500kHz?

[Anonymous No.1428788]

>>1428785
probably not, it most likely gets filtered out by distributed capacitance/inductance in the feed lines. maybe, just maybe, you might be able to pull in a nearby AM station using it as an antenna, or very possibly some power-line carrier utility internal traffic. the only way to find out for sure is to build a filter and hook your SDR up to it

[Anonymous No.1428837]

>>1428776
Of course you can, mains frequency is audio. Enjoy all the switch mode creatures you will hear. It sounds like in a jungle. As an RF antenna better use something else.

[Anonymous No.1428873]

BLOIMY THEITS A NOICE BIT OF KIT ROIGHT THEIR

[Anonymous No.1428876]

>>1424730
roll

[Anonymous No.1428928]

>>1423438
Its so good holy shit

[Anonymous No.1428940]

>>1427069
thanks anon you inspired me. I even managed to cobble together a prototype from my junk bin.
https://streamable.com/f3p4d

[Anonymous No.1429035]

is this the right thread to ask about fixing a speaker? or should I start a new thread for that?

[Anonymous No.1429037]

>>1428873
>whiny sperg who finds fault with everything
I don't know how this guy is tolerable irl

[Anonymous No.1429069]

>>1428650
An ion pump is used to pull ultra high vacuum.
When one wants to evacuate something, they typically use what is known as a roughing pump. But this vacuum is not perfect and there is still residual gas within the vessel. An ion pump is used to ionize and trap residual gasses within the vessel, creating an ultra high vacuum.

Within the scope of my lamp, it is just high-tech decor. The parts come from a very iconic machine.

[Anonymous No.1429076]

>>1428788
>hook your SDR up to it
I've only got a shitty one with minimum 25MHz, but I'll give it a shot.

>>1428837
I meant more actual audio being backfed into the wall from the variable load caused by people's amplifiers.

[Anonymous No.1429106]

>>1429035
yes, ask away

[Anonymous No.1429138]

I started this thread over at /g/ but no one has any ideas.

I've got these powered speakers which have an analog amplifier circuit inside. When I lower input volume and raise it slowly sound cuts out and then past a certain threshold I hear a pop and sound comes back in. I popped them open and couldn't see any swollen caps or burn out resistors. I'm a noob to this stuff, where should I start with diagnosing this thing? I'm guessing I'd need an oscilloscope to probe the signal on the board to see where it's going dead?

[Anonymous No.1429141]

>>1429138
Just to clarify, I'm not touching the volume knob, it's only the volume on the input device like the output volume from a phone or pc.

[Anonymous No.1429253]

>>1429106
I have Razer Mako speakers.
This isn't about the click of death issue that plagues that model, but it might be related.
Anyway i replaced a couple of capacitors on the board years ago which corrected the "click of death" problem. Ever since then, turning on the speakers causes the speakers to do a loud initial pop when when turning it on. It didn't used to do this. What could be causing this? more capacitor bullshit? There are no schematics that i can find though, and all articles i can find only pertain to the click of death problem.

Another problem is that if i power the unit down for a while, and then power it on again, there will be a mild hiss coming from the speakers that will eventually die down over a few minutes - what could be causing this and what's the fix? Hiss suggests noise which also suggests some capacitor again.

Last night, the subwoofer suddenly just got loud and was making white noise sounds (was not similar to the hiss that the tweeters make on initial power up) and i quickly turned off the unit. Today I turned it back on and it hasn't done that again - what would cause that?
Am i going to have to replace every fucking capacitor on this thing? I'm never going to buy another Razer product (I haven't for quite a few years - I've also have unpleasant experience with their mice) but while I still have these speakers, they're actually decent to my ears (other than the low level hiss on power up and the popping from the sub), so i'd rather not spend money on a new set of speakers if i can help it

[Anonymous No.1429270]

If I want to make an external amplifier for my phone to drive some low to moderate impedance headphones but I want it powered by the phone so through the microUSB and I do not want to use the AUX jack because that's too many cables how do I get the music off the phone?

I know I need a DAC, at least 16-bit, preferably 24-bit and I think I need a decoder but beyond that I don't know what kind of I/O needs to happen between the phone and the external DAC/amp. Is it when you boot up a music player app the digital audio data just magically appears on the D+\D- lines and all you have to do is put it through the DAC? If you have to decode does it matter what codec it was encoded with? I'm really not sure how to pull music off the device (incidentally it's a Moto G5+ if that matters)

[Anonymous No.1429290]

>>1428928
that's very good to know
>goes back to cursing at dual-row VQFNs

>>1429253
the caps you replaced were probably polarized, and you may have installed them backwards. or, you're trying to drive them from a speaker out jack and not a line out jack. or, there's local radio interference that wasn't there before

>>1429138
you're absolutely certain it's not your signal source doing that?

>>1429270
no, audio on the D+/D- lines is a rare feature. you need to search your own phone model to see if it can do that, and how to make it do that. have you tried xda-developers com?
audio decoding is a very deep rabbit hole. I'd let the phone worry about it. then you only have to build a USB audio class device (and hope your phone will condescend to recognize and use it). you'd find a USB DAC that fits your budget, then look at the datasheet for the reference design, then basically build that. beware, USB is a medium-sized rabbit hole
that said, you may as well just buy a $2 USB audio class dongle and OTG cable if the project isn't just for the learning experience. may as well do that anyway to see if your phone will allow you to use the similar device you've built

[Anonymous No.1429292]

>>1429270
The D+/D- is just a standard USB data connection, you'd use either a USB audio interface with something like I2S out into an I2S DAC, or have both functions integrated in the same chip. Android should just werk when you plug in a generic USB audio device.

[Anonymous No.1429296]

>>1429290
>>1429292
You know on second thought maybe it's just better to grab the audio off the aux instead and rather than using phone power I'll just throw a few batteries in the amp instead. LiPo cells and related charge controllers are pretty cheap.

No DAC, no decoder, still one cable, doesn't draw power from phone, and a fuckload easier by the sounds of things.

[Anonymous No.1429304]

>>1429296
your call

[Anonymous No.1429306]

>>1429304
I didn't realize there were single chip solutions for this with no programming required. I'm sure its expensive but I only need one.

[Anonymous No.1429308]

>>1429306
I prefer running analog wires between my constructions, makes it easy to whack a filter or effect pedal in between, not to mention use it as a standalone amp for an instrument. But if you can't see yourself doing that that's fine too.

[Anonymous No.1429316]

>>1429306
close to single-chip anyway, you might or might not want to add some extra boost if the output turns out not to be enough. about $7 in singles from authorized distributors or about half that from the ever scrupulous chinks
I'm sure there are 20- or 24-bit headphone DACs but I couldn't find any in my brief search

>>1429308
>not applying effects in-the-box
>2018
anyway pins 14 and 15 are perfectly analog and can be configured for line- or headphone-levels

[Anonymous No.1429317]

>>1429316
>applying effects in-the-box
Oh yeah, you might be able to make a neat UI for changing frequency response and such on a TFT touchscreen. That's a pretty nice idea.

[Anonymous No.1429328]

>>1429290
I definitely didn't install the caps backwards
the hissing, I'm virtually certain, is related to having messed with the innards. It never used to do that before i got the click of death problem (which was fixed by replacing those caps

And the other thing - what's the difference between line out and speaker out? What would that change / fix?

As for the loud pop when turning on the unit, I still have no idea what causes that

[Anonymous No.1429331]

http://cpc.farnell.com/sparkfun-electronics/bob-09816/opamp-breakout-lmv358/dp/MK00662
>Bandwidth is set to 15.9kHz by two feedback capacitors (over 100kHz with capacitors removed)
If I put 10GHz through this would it just blow up? I'm looking for a 10GHz amplifier module but most are about £200

[Anonymous No.1429341]

>>1429331
>10GHz
>LM358

lol good one

But seriously, parasitic capacitance will shunt all of your 10GHz signal to ground. You're output will likely saturate to the positive or negative rail and that's it. A mere 1pF of parasitic capacitance presents an impedance of about 16 ohms at 10GHz which might as well be a dead short compared to an op-amps high input impedance. This'll never work and if you wanna amplify microwave signals you better have the dough to buy the amplifiers because they do not come cheap.

[Anonymous No.1429348]

>>1429341
Fucks sake. If I sent 10GHz straight to an arduino analog input would it be able to read it un amplified?

[Anonymous No.1429353]

>>1429341
>>1429348
Don't worry fuck everything I've found a better idea

[Anonymous No.1429354]

>>1429331
Let me also add that there are slew rate limitations with the op-amp as well in addition to non-ideal properties like parasitics. The transistors inside the op-amp can only change their voltage so quickly and the LM358 is far far too slow. It only has a slew rate of 0.3V/us so assuming you powered it from a single supply 12V supply and assuming it can go rail to rail (it can't) it'd take 40us to go from 0 to 12V which corresponds to a maximum frequency of 25kHz. Woefully inadequate. You can do better if you lower your swing but even just going 0 to 1V is 3.33us which corresponds to a frequency of 300kHz. Still nowhere near what you need. Increasing slew rate really requires different methods of doping those transistors and very specialized design for microwave frequency circuits. You'll never see op-amps and will usually see discrete transistor amplifiers with heterojunction bipolar transistors or metal-semiconductor FETs.

>>1429348
No of course not. An Arduino isn't remotely fast enough to read a 10GHz signal. Are you retarded? Not being amplified enough is the least of your problems.

[Anonymous No.1429361]

>>1429348
I dont' mean to mock you, but dude, 10GHz is pretty goddamn fast for hobbyist level electronics. Hell even a few tens of MHz is pretty fast for hobbists, as i understand it. On the order of 1MHz, you start to need to look into specialized op amps, lookin at parasitic capacitances like the other anon said, keeping circuit loops short, keeping leads short, using SMD components.. and you're here wanting to toy with 10GHz

But out of curiosity what are you trying to do lol

[Anonymous No.1429365]

>>1429354
I'm being retarded
>>1429361
Project with doppler radar modules for a motion detector, most are 10GHz and have an IF output which presumably is the change in frequency, I didn't really want that though as I knew it'd be a ballache to get it working with the Arduino. I've just found this and ordered a few though, rather than an IF out it just gives an output voltage
http://hobbycomponents.com/sensors/899-rcwl-0516-microwave-radar-motion-detector-

[Anonymous No.1429369]

>>1429365
>doppler radar module
10GHz is the RF frequency, not IF. With most of the cheapo modules the output is just the difference frequency (+ a bit of 10GHz leakage which you can ignore), which unless you're tracking really fast stuff should be a couple hundered kHz at most.

[Anonymous No.1429371]

>>1429369
Shit really. In that case the Arduino could probably read it then? I would still need to amplify the signal though wouldn't I? The one that sends an output voltage would be easier tog et working but
>When triggered its trigger output pin will switch from (LOW) 0V to high (3.3V) for ~ 2 to 3 seconds before returning to its idle LOW state.
Would make it really slow

[Anonymous No.1429374]

>>1429371
Yes the Arduino can read it then and if you need to amplify it the LM358 should be fine as well.

I got a K-band radar gun off ebay awhile back and once disconnected the antenna and connected a sig gen to the IF input after the diode mixer. It could read speeds anywhere between 20-150mph in stationary mode. I don't remember the exact IF frequencies but by sweeping the signal gen I was able to determine the IF frequency corresponding to 20mph was around 1kHz and the IF corresponding to 150mph was about 8kHz. Knowing the doppler equation and the radar gun transmitting frequency (24.15GHz) you could calculate the exact frequency range if you were so inclined. It is low though and whole that range will change depending on your exact LO frequency it should still be in the low kHz range.

[Anonymous No.1429376]

>>1429374
Thanks for the help mate

[Anonymous No.1429377]

>>1429369
>>1429371
>>1429374
Not a radiofag here, but what is IF? Intermediate frequency? or something else?

[Anonymous No.1429385]

>>1429377
Yeah it's the intermediate frequency. It's the sum and difference products when you mix two signals non-linearly.

So with for instance a local oscillator of 10MHz and an RF signal of 1MHz mixing them will yield new signals at 9MHz and 11MHz. These are the IF. For doppler radar the principle is similar except your RF signal is your LO but doppler shifted corresponding to the target velocity. So you you might transmit with an LO of 24.15GHz which hits the target and gets doppler shifted to 24.150005GHz which then gets mixed with the original 24.15GHz signal yielding IF frequencies of 5kHz and 48.300005GHz, the latter of which is typically filtered out.

[Anonymous No.1429743]

Ow just shocked myself with 250VDC. Though considering its a boost converter with zero feedback running off my laptop's USB supply I'd say it's not the worst outcome.

[Anonymous No.1429788]

>>1429743
is 250 pretty bad? NAfag here. I've accidentally (and in occasional the past as a child, intentionally) had 120VAC across my hand. Its unpleasant and I wouldn't want to feeling to stay around, but i wouldn't say it hurts.
Although I think i recall once as a child, that eventually it would feel hot

[Anonymous No.1429792]

>>1429788
Not as bad as an electric fence by far, though only because it was DC. The fact it was only buffered by 470nF probably helped also. It's an unregulated boost converter running off 5V at around 1kHz, but I've never been shocked by mains before anyhow so I couldn't compare. End goal is 400VDC for a small geiger tube. It's on a breadboard too, which I'm surprised works. At the moment it reaches a little over 300VDC without a load, though the 10MΩ of my DMM drops it to around 170VDC. I plan on using 10M for the feedback divider, so the DMM acts as both the measurement device and the load.

I imagine being shocked by 240 is much less common than being shocked by 120 due to the differing attitudes towards its danger.

[Anonymous No.1429796]

>>1429792
You probably loaded down your output and the voltage dropped below 250V. Its hard to design DC-DC converters that draw a lot of power and can supply more than a few mA continuously. Trust me, I tried to design a flyback converter to drive 20 IN-9 tubes off a 12VDC input. Max full scale current was like 12mA per tube * 20 tubes is 240mA at 170V is about 40W. Unfortunately due to the nature of the tubes they don't lend themselves to multiplexing either.

[Anonymous No.1429804]

>>1429792
Just replaced the diodes with UF4007s, and I'm getting much better performance already. I'm at 10% ripple with the output settled at around 300V, so I'll definitely try to improve that.

>>1429796
I know that, part of the challenge will be optimising it to get a max voltage that's significantly above my 400V goal. But I'll be adding the feedback long before I do that, I don't want to fry anything. I've got a 10nF as well as my 470nF cap, think the 10nF will be better? Chances are I'll have to increase my duty cycle (currently 9%) or go for a different frequency. I'm just glad I didn't overshoot the voltage rating of my original IN4004s when I first booted it up, I honestly didn't expect it to go past 30VDC hence trying it without the feedback.

[Anonymous No.1429817]

>>1429804
SMPS can work fine without feedback as long as your load draws a relatively constant amount of power. If your load draws power more erratically you want feedback to allow it to adjust to the demand.

I'm not sure what you mean with your cap? Is that your output filter cap? 470nF would make for lower ripple. 10nF is a much faster charge so you'd probably be able to get a higher output voltage with it but with high ripple and miniscule current output so even very light loading will pull the voltage down. As for feedback you do it with a resistor divided if you don't care about isolation or with more complex networks involving feedback windings on a transformer or an opto-isolator. Not aware of capacitive feedback networks, at least that kind of thing wouldn't be common in this application. A schematic would be helpful.

[Anonymous No.1429831]

>>1423156
Does anyone have a link to the 100+ page application note that discusses working with high frequencies?

[Anonymous No.1429833]

>>1429792
>I imagine being shocked by 240 is much less common than being shocked by 120 due to the differing attitudes towards its danger.
It is.. It's still not uncommon though. I'm aware of 4 people getting shocked at my previous workplace where I was for 9 months. And that's out of 20 people, where only 5 were supposed to work with electricity. Two were through the same breaker switch that was live due to water getting in the box it was in. One due to working with a screwdriver that wasn't insulated because he couldn't be bothered spending five minutes going back to the workshop for a proper one. Last one was a kid who just wasn't very bright and had been shocked fuck knows how many times.. Also the only one who went to the hospital for the ekg...

[Anonymous No.1429837]

I am having troubles with a thermistor.
I have ntc 640-10k and I wanted to use in this radical new way and try to measure temperature with it.
Turns out it's really shit at it for some reason.

So basically, I have this heated pad and i want to measure it's temperature so i ducktaped the thermistor to it but its readings are shit.
My temp gun shows the pad under the thermistor is 70C which is corrrect, but the thermistor only says it's about 40C which is bullshit.
At first i though the problem was in my analog to digital capacitator timer which i use to read the resistance from the thermistor, so i used my multimeter to read the resistance directly, and sure enough the thermistor was only outputing resistance consistent with 40C reading.
So what the fuck is going on here? I taped the thermistor in a way where it is directly touching the heated pad.
Yet when the pad is turned and at room temp, about 25C then the resistance of the thermistor is consistent with 25C so it doesn't seem to be broken.

[Anonymous No.1429839]

>>1429804
do you know whether your inductors are close to saturation? higher operating frequency will fix that. 1kHz doesn't sound nearly high enough to push any limits of a small switcher. even 5-10kHz should be well within the capabilities of a breadboard
in any case, if you want more voltage, just turn up the duty cycle and make sure your caps are rated for the desired output
>surprised
you're doing just about what those electric fly swatters are doing, and those get up to 1000V or so

>>1429831
uhh, can you be more specific

[Anonymous No.1429845]

>>1429817
Just the output filter cap. In my experience modelling these with spice the output cap has some effect on the output voltage, but the models are hardly accurate in other ways. For example, my output is going above 5V when the 555 timer that powers the FET is not even active. Anyhow I'm going to stick to a model with feedback, because of thermal drift and such. I think the individual radiation cascades could cause drops in the output voltage also.

>>1429839
>close to saturation
Probably not. Just from basic intuition, I think longer individual pulses will give you more inductor output power than lots of shorter ones for the same timespan, but that's what experimentation is for anyway. Higher frequency will make my output smoother in any case. I'll use a 47k/10M divider, an LM311, and I'll test a variety of ways to use this to interrupt the clock signal. Is just powering the RESET pin on the 555 the best way? Currently I'm powering the FET's gate directly from the 555's output, apparently putting a resistor in there might also be a good idea, though I don't believe an active driving circuit is necessary. I'm using an (import) IRF840 and a 470µH radial inductor, plus the aforementioned UF4007 diodes. Pic related, though R5 and R6 haven't been calculated yet, and C5 was just experimenting.

>>surprised
Only because the thing wasn't tuned at all.

>>1429833
I was more referring to "domestically" or "as a child", it would definitely be more common in industrial environments.

[Anonymous No.1429848]

>>1429845
>Just from basic intuition, I think longer individual pulses will give you more inductor output power than lots of shorter ones for the same timespan
only due to diode losses, switching losses, self-capacitance losses, breadboard capacitance losses, ohmic losses, etc. if those are minimized, current in will very nearly equal current out
>interrupt the clock signal
if you're just using a 555, why not take advantage of the control voltage input and do proper PWM?
>resistor
no, you don't need or want this. it just slows down the FET, whose gate is basically a capacitor. if you need to clamp the gate voltage because of the FET spec, you might need a simple driver on the output
>pic related
nice pic, anon

[Anonymous No.1429849]

>>1429848
>current in will very nearly equal current out
Yes exactly. The exponentially ramping of the current through the inductor will reach higher peaks with longer pulses, and so the integral of 2 longer ramps will be greater than that of 4 shorter ones.

Doing proper PWM feedback is a little alien to me, do I just feed a shifted and attenuated voltage into the CV pin?

Apparently a small resistor is good to prevent inrush current to protect the 555, but it's doing fine at the moment.

Oh fuck, here's the image.

[Anonymous No.1429851]

>>1429849
Actually I'll solder a current shunt to some breadboard leads so I can measure that with my scope as well, to see how the current through the inductor behaves.

[Anonymous No.1429854]

>>1429849
>The exponentially ramping
that would be unusual
>do I just feed a shifted and attenuated voltage into the CV pin?
er, my bad. the CV input is better used for FM. otoh, if you have an opamp or totem-pole-output comparator, you can use the 555 as a triangle wave generator, taking the tri wave (1/3Vcc p-p, 1/2Vcc offset) from pin 6, and use the opamp/comparator output to drive the FET. one input is the shifted and attenuated output voltage, the other is the tri wave

[Anonymous No.1429856]

>>1429849
actually, this one's kinda clever https electronics stackexchange com/questions/175967/how-do-i-use-pin5-to-control-duty-cycle-of-a-555-based-pwm

[Anonymous No.1429860]

>>1429854
Shit, the ramp is an opposite exponential because it's an inductor, so high frequency is actually better. Which is good, because I was thinking that 1kHz is already pretty low.

>>1429856
So one solution is just running a feedback voltage to the CV pin, which alters the on time but not the off time, hence being both PWM and FM. The other being just using the 555's "triangle wave" with a comparator, which I guess I should have thought of earlier since it's a nice elegant solution. Tuning it sounds like a bit of a pain so I'll go for the bang-bang controller method for now until I can get some data for output voltage as a function of duty cycle and frequency. I already feel stupid for using a 555 instead of an op-amp oscillator since I could do the oscillation and feedback with a single DIP-8 dual comparator IC.

My goal is to get a working geiger counter before I finish eating all the Brazil nuts I bought to test it on.

[Anonymous No.1429914]

>>1429860
>before I finish eating
400V 50µA ? Buy another batch or three..

[Anonymous No.1429921]

>>1429860
>data for output voltage
current in ~= load current + loss current. with no load it will build up as far as breakdown voltages and losses will allow. that takes care of duty cycle. frequency shouldn't move the needle very much, as it were
>Brazil nuts
kek, were they from Goiás?

>>1429914
does Pic related help? the TPS61040 is a pretty typical switching converter and section 8 on component selection should be pretty portable

[Anonymous No.1429923]

Say I get a module like this, where the volume is controlled by a rotary encoder instead of just a pot. What happens if I remove the encoder? I want to use it with an amp and just use the amp's volume control.

https://www.ebay.co.uk/itm/87-108MHz-DSP-PLL-LCD-Digital-Stereo-FM-Radio-Receiver-Module-Serial-Control-/142818151226

[Anonymous No.1429925]

>>1429923
you'll just have to try it and see

[Anonymous No.1429927]

>>1429914
I've got 5 left, I'll get started again tomorrow.

>>1429921
They're an excellent source of Potassium 40. That data looks pretty useful.

>>1429923
I assume the thing will have a default volume level, so removing it will just have it stay at that level. A pull-up or 0Ω link may be necessary to emulate a motionless encoder. If the default volume is fine for your purposes, i.e. you don't need an extra preamp but the quality is fine, and/or it remembers the last used volume, then no worries, else you're probably going to want to throw a small MCU like an ATTiny85 there to pump up the volume on startup. That shouldn't be necessary though. Such rotary encoders are entirely passive devices so don't be afraid to desolder one and do a continuity check. If it's a push-button encoder then you may also want to add an extra button. Encoders are neat.

[Anonymous No.1429930]

>>1429927
>a small MCU like an ATTiny85\
possibly. there's already a 24C02 on board. maybe that could be preprogrammed to the correct settings for anon's purposes

[Anonymous No.1429933]

>>1429927
>I assume the thing will have a default volume level

I guess that makes sense, it's not like you're going to turn it up from 0 every time you turn it on so it must have a default or some non-volatile way to remember the last setting. I'll get it and see how it turns out.

[Anonymous No.1429991]

>>1429921
>pretty portable
Yes, the entire design procedure section is a good read.

[Anonymous No.1430128]

I need to generate fairly loud ~1ms sound pulses at a specific frequency in a way that's controllable by a computer. What's the best/cheapest way to do this? Are regular speakers capable of such short bursts?

[Anonymous No.1430134]

Whats the best way to get a good explosion from an electrolytic capacitor? Reverse polarity with a 12v source wasn't that great with just a slow release of gas from the cap, upping it to 24v sped it up and I got a bit of a pop from one of them but still nothing like the big explosions you see in youtube videos.

Do I need more reverse voltage or is it better to connect them the right way and over volt them? These were 12v car batteries in series and both are in good condition and hold at 12v under load, the capacitors drew about half an amp max.

The capacitors were pulled out of spec low esr types from a SMPS, they all vented from the rubber bung rather than the vent at the top which surprised me.

[Anonymous No.1430158]

>>1430134
just straight up plug them into an outlet, preferably a power strip with a switch on it

[Anonymous No.1430159]

>>1430134
Use a larger cap and connect it directly to the mains.

[Anonymous No.1430161]

>>1430158
>>1430159
Will around 70v dc 500mA do? As I would like to have isolation between the cap and mains, don't want to trip the RCD. Is it better to over volt or reverse volt these things?

[Anonymous No.1430164]

>>1430161
it won't trip the breaker, I've done it multiple times
and you're being overly cautious, it's really not that dangerous

[Anonymous No.1430168]

>>1430164
Which sizes of capacitor usually give the best bangs? Most of mine are the typical output caps from SMPS ie 25v 470-1000uf but do have a few of those little 1uf 50v types.

In my case the 470uF was the only one that gave any pop, the rest just gassed gracefully.

[Anonymous No.1430173]

>>1430128
>~1ms sound pulses at a specific frequency
what frequency? if the sound is less than 1000Hz you won't even get one cycle of the sound - just a click.

[Anonymous No.1430181]

Is recreational cap-sploding something that people do?

[Anonymous No.1430191]

So I've got an old motorbike and I want to replace the indicators with LEDs. I'm told I need to put in a winker module inline to make them work. Is this just an astable oscillator controlling power to the LEDs or is it something more fancy?

[Anonymous No.1430238]

>>1430191
Well you'll need to replace the original oscillator, which I think is a relay-based oscillator dependant on the current drawn by the indicator bulbs themselves. An astable oscillator should suit you fine. Though depending on how your LEDs want to be driven you may want to switch something other than 12V, such as a current-controlled source.

[Anonymous No.1430305]

Boost converter feedback is functional, after fucking around for 30 minutes thinking that the EMIT OUT pin meant the output of the comparator. Turns to it has both a collector and emitter output, so you can decide whether to run it in CE or CC mode.

[Anonymous No.1430333]

>>1423156
I've found a laser (LED in fact) color printer.
It is toast. Fuser is ripped apart, and it can't detect drums properly.

What can I salvage from obvious power supply and motors? And what can I do from it?

[Anonymous No.1430371]

>>1430305
And I can get over 400VDC. Increasing the frequency by a factor of 5 actually decreased the maximum voltage (saturation?), so I swapped it back to 1kHz and increased toe duty cycle from 10% to 33%, which did the trick. Now I'll see about bodging together a circuit with my SBM-21 tube, and maybe with a piezo element I found. Though the tube itself worries me because the centre electrode was actually hollow and full of solder, so by soldering onto it I melted that solder and possibly disturbed the gas mixture/pressure on the inside. The fucking tube also was stainless or maybe something even worse on the outside, so even after scraping at it with a drill bit covered in flux I still couldn't get anything more than 0.25 square mm to wet. If it doesn't work I'll buy a proper tube, with a mica window for alpha detection.

[Anonymous No.1430406]

>>1430371
Tubes have clips, no soldering. Which component has the EMIT OUT pin?
>saturation?
No, ton too short = flux too low or L too large.
Keep the capacitive load of the tube as low as possible (pF) or it won't live long. No direct piezo.

[Anonymous No.1430420]

>>1430181
I had a buddy in high school who used to do that

>>1430333
>I have junk, what do?
Take it to the recycler.

[Anonymous No.1430421]

NEW THREAD
>>1430418
NUEVO TEMA
>>1430418
HOBAЯ TEMA
>>1430418

[Anonymous No.1430423]

>>1429837
So the thermistor was in contact with the heater from one point, while the rest of the thermistor was free to dissipate heat?
You need a very good thermal contact and you need to minimize the heat leaks. On small thermistors the wires tend to be a significant heat leak.
Also, NTCs are highly nonlinear. How did you convert the resistance to temperature?