/diy/ - Do It Yourself

this thread's digits brought to you in part by the MPSA62 Darlington pair

making a schematic in kicad, don't know much about making schematics I'm just using it for a reference for a project since I can't draw well, anyway I've got the full thing mocked up but it only takes up around 30% of the sheet, any way to scale all of it up in terms of size?

>>1390136
Just make the sheet smaller

>>1390137
after that can I then export it to a4 size? for printing it out

>>1390137
also I just googled make sheet smaller kicad and it didn't yield any good results so can you tell me how to do it please?

>>1390136
it's fine, anon. there's nothing wrong with filling in the middle of a whole sheet
>file / page settings / custom page size

>>1390140
In the KiCad project manager, under Tools->Run Page Layout Editor.

Is there a version of this 28BYJ motor that is bipolar rather than unipolar? I don't want to take off the little cap, snip a trace and crimp a new connector just to use it with a A4988

>>1390238
Or just slap it on some perfboard.

>>1390066
Is the emitter and colector on a transister interchangable or just 1 way direction?

I was replacing a charging port in Nexus 5X. Unfortunately I fucked up the airflow and blew away a resistance along with an IC, I managed to resolder the IC but lost the resistor

How fucked am I?

>>1390338
Just one way. That thing is a PNP, most transistors you'll come across will be NPN (emitter pointing out). NPN is more intuitive and apparently slightly more optimised.

>>1390351
Ok thanks

>>1390066
>>1390338
>>1390351
Sziklai pair's are better than Darlingtons because they only have one Vbe drop instead of two. The only drawback is the name, I'm still not sure how it's pronounced (sizz-ē-klai?)

>>1390339
welp that was an RF chip, I guess I'm fucked

>>1390365
Ah, I see how that works, quite elegant.

hey guys why would my battery charging unit recommend a 6 gauge, 60cm line on the negative terminal on my marine deep cycle boat battery?

>>1390369
Kaptan tape in the future lad

>>1390338
strictly speaking, yes, but the transistor you get the other way really sucks

>>1390369
maybe. it's not unusual that such circuits are built closely to reference designs. if you can find a datasheet you might be able to get a replacement.
what the other anon said about kapton tape. it will change your life

>>1390374
shorter and thicker is better

>>1390365
boldly speculating it's more like sheek-lie

>>1390376
>Kaptan tape
Not him but what for? Do you just tape the components down?

Is there such a thing as too large a capacitor value? Like if my circuit calls for a 0.22 uF, and I don't have any, but I do have some 220 uFs, is there a reason why I couldn't just use them? They'll be around a linear regulator.

>>1390508
>Is there such a thing as too large a capacitor value?
Sometimes, but only in that a particularly large capacitor will have a higher ESR, or will be of a different type, provided it's in DC. If in AC then you'll have a different time constant which usually isn't acceptable, and possibly the filter cap of a switched-mode power supply shouldn't be too big else it messes with the circuit's calibration. A very large capacitor from power rail to rail could cause inrush current problems; it may pull so much current that your power supply dips or worse.

The ~100nF caps around a linear regulator are noise-suppression capacitors of some sort and should be ceramic or polymer dielectric. Using aluminium electrolytic capacitors for this is ill-advised, but it's not awful. But buy yourself a general purpose pack of ceramic caps, they're a dime a dozen and damn useful for this purpose.

>>1390505
shields the components from the hot air.

Hey op could you uhh add the mega links and whatnot to the manga that were posted in the last thread to the opening post the next time.

Ok so just checking, i got this heatbed for my printer, it's basically just a big resistor and a thermistor if i understood correcrly, does it matter at all way which way i plug the heating wires and the thermistor wires? (they obviously have their own ports i'm not talking about that, just wondering if + and - matter)

>>1390537
so long as the heatbed doesn't have the heater/thermistor ground pins connected together you can hook it up either way round, makes no difference.

I got one of these external USB optical drives.

It comes with a "Y" cable in the box, one mini-USB on one end, 2 USB A on the other end, one is data, other is extra power because the drive consumes a lot of power. Now the original cable is broken and can't get a replacement because it's non-standard and I have to import one from china and risk it being a bad quality one yadda yadda...

I used several high-quality regular mini-USB wires but they last nothing until they become resistive enough that the drive resets when trying to spin-up the disc because it power-starves.

I was thinking about adding an external power input to hook it up to a wall power supply or one of those phone chargers (5V 1+A).

The plan is to add a diode to the original port to avoid the external PSU supplying a voltage to the computer (back feeding power to the computer's USB port). Now I was looking at the circuit inside the disc writer and what I found is that it has some kind of voltage sensing, maybe brown out protection and that makes it more difficult because of the circuit layout.

Should I connect that to the external supply point or keep it on the computer's USB?
I'll make a diagram of the original circuit and what I'm planning to do.

Now this looks simple enough but the board layout makes it require botch wires jumping from one side to the other, which I dislike a lot.
The sensing circuit is on the top right at the side of the USB port but the part I'm gonna break to install the diode is on the back side of the board.

>>1390607

the diode will ensure that no power is ever taken from the micro-USB under normal conditions. so, you should simply replace the diode by an open circuit, and power the drive strictly from the phone charger. should be rated 5v @ 2A or better.

Theres a machine at work i have to put thermistors inside. Problem is that there are high alternating currents in the machine that are picked up by the wiring. I get a stable reading when the machine is off but when its on the temperature jumps around +-20C.

Would a shielded cable help or will i pick up the same noise where the shielding is open where i connected the thermistor? Should i consider an I2C thermometer?

>>1390847
either of those or a digital filter would work.

>>1390847
the problem is most likely the large source impedance. at each sensing location, you could put an op-amp voltage follower and the thermistor's bias resistor, and run a 3-conductor cable to each one
>should I consider an I2C thermometer
consider 1-Wire

>>1390857
>>1390863
Gonna try a shielded cable.
Then that or similar thermometer.
Thanks

How well used in industry is Multisim, does anyone know? Should I just bite the bullet and go learn Simulink or whatever the fuck? This seems to be one of the many ways my college spent 4 years making me work my ass off learning the wrong things.

>>1390603
I have one of those too, I'd check if your one has any diodes to begin with. If you don't have it with you I could check mine in 6 hours or so when I get home.

But yeah just making data go to the computer and power come from a 2A wall-wart is probably a smarter idea, it's something I've been meaning to do since my computer doesn't have 2 USB ports on a single side. It still works for the most part with a single USB A though, I'd check if you need the extra power.

>>1390847
>>1390857
>>1390879
Shielded cable did nothing.
Ill go for the other option.

>>1390062
Hey /ohm/ I posted previously needing help figuring out how to heat up nichrome wire using batteries to power some heat activated material actuators. Now I have returned because I want to seal these actuators in something that is flexible, non-conductive, stable up to 200F and water resistant so that I can weave multiple actuators into a hammock pattern and cool them with water-evaporatively.

I have been looking at different types of graphite-silicon sprays and rubber based sealants, but I wanted to hear what you guys thought before I bought. I will post some pictures from my project here to gain some interest.

>>1390925
In order to get the amps I needed I put some 9 volt cells in parallel.

>>1390925
If it's just boiling temperature then I'm sure normal silicone will do the trick, silastic or epoxy will definitely work, though epoxy isn't flexible once cured. Hot glue will do the trick if you're desperate. Don't forget to add a temperature sensor to tell you when to shut off the heater.

>>1390927
Fuck, not sure if I should be shocked or glad that you're not using lithium ions.

>>1390702
At the end I did it like my original idea, opened the mini-usb, dioded it up, patched the sensing resistors and ran a wire to an external connector.
Worked a treat, the drive works with both power sources and doesn't leave powered on other devices on the same hub.

I also documented on like 6GB of video so I'm probably gonna cut and paste then upload to youtube for future reference.

Could anyone help me troubleshoot a bigmuff build? When I hooked it up to my guitar and amp, it seemed not to be passing any signal, but then when I hooked up a signal generator to it, it seemed to pass some signal, but it was very quiet. Any advice where I should start looking? I checked the diagram, and it seems to be wired up alright.

I have a problem with my PS2 I'm trying to repair. It powers on, but no video or audio. I swapped out the PSU and minor components with another console, so I'm certain the problem is with the motherboard.

I'm new to electronics, but is it possible to check the amperage of a fuse while it is on the board in circuit? I found an image online illustrating where the fuses are located and their respective values. But I'm getting nothing out of my multimeter except for continuity and resistance readings.

How do I hone in to find where the problem is?

>>1391138
Idk if this is the problem you're having but it has to go into the ammeter and out the other lead

Easier to get voltage and resistance readings and ohm's law to get a current value

my bad if I misunderstood, good luck

>>1391138
Guessing you can't remove the fuses then. While it's running, I'd test for a voltage across the fuse, if there is a large one then the fuse has blown, if there's a tiny one then it's currently functioning, and if it's zero it's either functioning or not active.

>>1391138
>I'm new to electronics, but is it possible to check the amperage of a fuse while it is on the board in circuit?
Technically yes but you need specialized equipment.

Hey guys, I’d like to make a timer that sends a dc voltage about 2 volts how would I do this? Also how do I control the dc signal to be positive or negative? Thanks

I'm planning to use a solid state relay to turn my hot water heater on and off to save energy since I use very little. In my testing, I used a lamp with a CFL bulb as the test load. Whether or not the DC input to the SSR is open or shorted, the CFL blinks very faintly two or three times per second when it should be off. I have two different SSRs from different manufacturers and they both do it but one seems to be a bit worse. One is rated 280 VAC 25 amps, and the other is rated 240 VAC 25 amps, and the test is being done with 120 VAC and a 23 watt CFL.

In the actual application, the brief pulses will not be that bad and should not harm the heating element, but I'm surprised that the SSR is not 100% off when it's supposed to be. I have very little experience with triacs or whatever is in the SSR, but does this seem normal?

>>1391244

Here's the voltage, so it's not spikes or pulses so much as a very small trashy 60 hz signal, which is strong enough to produce the CFL flicker, and will be negligible when connected to the water heater.

(Does anyone else hate trying to enter a filename on a Rigol scope?)

>>1391244
>normal?
Yes, RC snubber network.

>>1391251

Thank you sir. Someday I'll learn to read the spec first.

>>1391210
More info needed:
>what you mean by timer: an oscillator, single-time delay, repeating delay
>what you'll be doing with that 2V: how much current or power, how stable it needs to be, what it's referenced to

>>1391244
If you're not switching it more than 5 times a day I'd use a mechanical relay instead. Oh and if it's a normally-open relay, regardless of type, try to power it off the same phase as the tank to avoid dropping a phase and having the tank off when it could be on, not that it's a common occurrence.

>>1391253
>If you're not switching it more than 5 times a day I'd use a mechanical relay instead.

I already have a pile of SSRs from old projects, and I more or less assumed they were superior or at least equivalent to mechanical relays. I plan on switching it on and off once per day, just enough so I can take a comfy shower.

Why would you prefer a mechanical relay; I can certainly buy one if there's a good reason.

I need something that generates a ~1s pulse on a change from low to high. If I'm not mistaken, the 555 does a pulse, but if the input stays high, the output stays high as well. What's a better way of solving this?

>>1391469
>the 555 does a pulse

the mighty 555 can do just about anything you want

>>1391469
https://www.electroschematics.com/11032/edge-triggered-555-monostable-multivibrator/

>>1391472
Apparently, but I'm not deep enough into electronics to figure out my own stuff with this godly device.

>>1391482
Awesome, thanks! I shall try to dive into this black magic and see if I'm worthy.

>buy sensor on aliexpress
>can't find datasheet on google
>seller wrote on the item page that they'll send the datasheet to you if you just ask
>pls give
>here you go friend!
>pic related
T-Thanks...

>>1391491

I'd start with /int/ and maybe some of the international subreddits, and I bet you'll have the english version within hours.

>>1391504
Yeah i guess. I also have some chinese friends IRL i might ask.
Otherwise, I suspect it might just be a knock-off of this sensor: https://www.sparkfun.com/products/639
Do you think it would be safe to use the datasheet for that to try and make sense of the one I bought? Or would I risk frying it?

>>1391563
>Or would I risk frying it?

If everything looks very similar, then give it a try. That pic shows things like VCC and GND so if yours does, you are PROBABLY going to be ok...

If I have a secondary (receiver coil) that I'm supposed to measure voltage across, should I connect one side to the ground or keep it floating?

If I connect one side to the ground I'm just getting short voltage spikes.

If I keep it floating, I'm getting a semblance of the square-ish signal (with the spikes still present) that's driven through the primary (transmitter) coil. The problem is I'm also listening to the 50Hz mains voltage if it's floating.

Pic related is one probe (green) connected to one side of the secondary coil, ground on separate ground. Yellow probe is connected to the other side of the coil, ground also on separate ground.
Middle signal is the difference (Yellow minus Green), which is coincidentally the same voltage I get if one side is grounded and just measure the voltage on the other side.

So my question is, Am I looking at any sort of useful signal in the Yellow and Green signal separately, or is it just crosstalk from the driving signal? Yes I know crosstalk is desirable in some way but I don't really understand if I'm getting any sort of useful information from the those signals, am I?

This system is used for some form of eddy current testing, the primary is the driving coil and the secondary should be the receiver coil

>>1391135
transistors installed backward?
double-check resistor values?
if that fails, unsolder the jack from the output, connect the ground wire to the circuit ground, tack a spare capacitor onto the signal wire (you do have a spare capacitor, don't you?) and poke it into the circuit along the signal path. your ears will help you find the culprit

>>1391288
then by all means use what you got.
>superior or at least equivalent
that depends, of course
>why mechanical
cost would be a factor, but your SSRs are "free" anyway, which changes the balance
fwiw, CFLs are not good test loads for solid-state switching

>>1391595
what are you driving with the receiving coil? if your input impedance is too low, you would get a high-pass filtering effect
>50Hz mains noise
consider a capacitor (preferably a safety cap) from one side of the coil to earth, and a large (hundreds of kohms) resistance to 0V

>>1391623
>what are you driving with the receiving coil?
just a 1 kohm resistor is connected on it, only thing i had lying around

So you're saying try with a cap to the ground, and a several hundred kohm resistor

Do you expect i'll see the square-ish voltage then?
I can kind of see your point, the coil would be slower to lose energy, the cap would filter out the noise, but wouldn't it also filter out higher frequency components? The signals I'm measuring is in the range of hundreds to thousands of khz

Center positive dc jack is the most common configuration these days?

http://s1.downloadmienphi.net/file/downloadfile6/192/1385077.pdf

>>1390925
What the heck is that?

How much hotter does this little stepper motor get if I run it on 12v rather than 5v? Also, if I run it with an A4988 and set it to a really low current, like 400ma, will it get extremelly hot? My 3d printer motors get barely warm running on 24v, but they're a bit different from this

>>1391679
>tfw going to need to take a course on physics to understand this book on more than a very general level
:(

>>1391694
at dc you'll be dissipating 6 times more power in the windings. (12/5)^2. you can't expect it to survive that.

my multimeter tells me the winding resistance on those is ~22 ohms. so you'd want to set the pwm to 5V/22 ohms=230mA. mine is unipolar though and i thought all of those shit motors were. are you sure you have a bipolar that the A4988 can drive?

>>1391705
>are you sure you have a bipolar that the A4988 can drive?
I will snip off the trace to the common wire, by doing that it becomes bipolar and it can be driven with the 4988. I have a box full of A4988's I can't sell because they're the clones unsuitable for 3d printers because they generate awful resonance, so I'm going to use them for robot arm kits instead.

>>1391641
yeah, 1k is pretty low for that sort of thing
>filter out high frequency
come to think of it, the cap might not be necessary, but you'll still want to bias one arm of the coil to some reference potential with one or two resistors. output should look more square with that lighter load on it
if you still have low-frequency problems, you have 4 orders of magnitude between wanted and unwanted signal, which allows a lot of latitude in filter design

>>1391724
>you'll still want to bias one arm of the coil to some reference potential with one or two resistors
What do you mean by this, just put a huge resistance between one arm and the ground?

>output should look more square with that lighter load on it
do you mean bigger load?

>>1391491
Install google translate on your phone, it has a built-in text recognition (if you give it the language, it can't guess otherwise)

>>1391739
right, then you have a differential signal you can feed into an instrumentation amplifier running on a split supply, or a balun or whatever
>bigger
I'm thinking lighter as in more ohms, so more volts per current induced in the coil, and less interaction with the material phenomenon under test. I still have no idea what meters/instruments/etc. you intend to feed with this signal. are you just gonna watch it on a scope?

>>1390062
Hey folks
Lets say I have a 110v 100a power supply and a 110v 1 amp load. How would I resist the current of my power supply down to 1 amp in order to squeeze whatever is left of my power supply into my load? lets also say everything is 100% effiecient

>>1391813
your load will allow 1 amp thru it when 110v is applied

if its resistive you will have to increase the voltage to toss 99 amps thru it

>>1391813
your power supply is a "constant voltage" supply unless it says otherwise. that 100A value is just the maximum it can provide before it limits or dies. it'll only give as much current as the device needs. it's a common misconception, unless you're asking something different.

>>1391813
>110v 100a
Jesus christ, what gauge of wires does it have?

>>1391841
The biggest gauge bro

>>1391821
Even for AC?

>>1391845
Yes, even for AC. I = V/R.

>>1391845
Your wall socket is a 110V 15A socket and it doesn't push 15A into your phone charger. The phone charger only needs 0.5A or so, so that's what it drains.

I want to make my own game controller from tactile switches
I know they probably use some sort of key matrix and then some sort of converter and interface IC for communication over USB
perhaps it would be easier to use an arduino as the interface?

but I don't for the life of me know how to un-abstract this into a concrete blueprint or what parts to get or what I need to do on how to build it, how to even get the computer to recognize it as a controller, etc
where do I go from here

>>1391821
Hang on a minute, so you’re saying the my 110 v 1 amp light bulb will not over heat from my 110v 1000000a AC power supply?

Lets say I had 50v 100a AC power supply and I wanted change it with a transformer that 50v to 100v 50a , but the transformer said 50v 2a input to 100v 1a output why doesn’t the transformer heat up? What would happen to the transformer and power?
Does the power just wait there until the pathway gets bigger or something like that until then the power just goes through the transformer and the transformer does its thing?

>>1391866
your game controller will need to use USB HID to emulate keyboard/mouse unless you want to write your own drivers. evidently arduino has an HID library available, but it's not something you can use through the normal ide since i assume you need to program the programmer too. i haven't ever touched this, and i have minimal experience coding for usb, but i can say this won't be entry level on the software side.
http://mitchtech.net/arduino-usb-hid-keyboard/

you shouldn't really need a matrix since you have so few inputs on a controller. you can most likely just use a perfboard, cut it to shape, and shove it in a printed case. designing your own pcb is fun though.

>>1391872
>Hang on a minute, so you’re saying the my 110 v 1 amp light bulb will not over heat from my 110v 1000000a AC power supply?
yes.

>Does the power just wait there until the pathway gets bigger or something
yes. the power supply's 100A is a "do not exceed" and is meaningless in any other way. so for V=IR, you don't know "I" until you know what your load is. you can consider for basic things like these that a "110V, 1A" device is just a 1.1 ohm load. so 110V/1.1 ohms = 1A.

regarding your transformer, you can eliminate it from your circuit mathematically. your transformer has a 1:2 ratio (50v:100v). if you had a 100 ohm load running off it then you can divide the load by the ratio squared and conclude that your power supply sees a 25 ohm load. the amps rating on the transformer is also a "do not exceed" number.

>>1391875
a brief glance at that mitchtech website and it isn't looking too terribly difficult. If I have to write my own drivers, that's when I'm in way over my head. Believe me, I'd love to, I just have no idea how.

>>1391866
Take a look at what the /g/mkg/ guys do for custom keyboards.

Y'all got a good video to watch for basic soldering and tip care? I keep thinking I have it, but then I struggle with it. I'm not sure if it's because half the things I'm trying to fix are lead-free, or if I'm just terrible. Getting a bit discouraged.

>>1391880
Bro I’m learning HEEEAAPS, thank you! sorry this is just a personal question but I’m sure others can learn too

Lets say I have 240v 100a AC and want to power a load that works off 48v DC
without losing any current when recifying AC to DC assuming that we have diodes that are 100% efficient that exist. How would I arrange the diodes?
lets say the diodes I have are 48v 10a
This is how I think I would do it
240/48= 5
100/10= 10

Then arrange the 48v10a diodes 5 in series then duplicate that pack into 10 rows that will sit parallel and that way I’ll have 48v DC and retain 100a current

Kind of look like this
* this “-“ is a diode

12345
1 - - - - -
2 - - - - -
AC 3 - - - - - To DC 48v
240v 4 - - - - - Load
100a 5 - - - - -
Supply 6 - - - - -
7 - - - - -
8 - - - - -
9 - - - - -
10 - - - - -

>>1391901
Damn, 4 chan messed up my amazing illustration

>>1391881
fortunately, you don't have to write your own drivers on the host side, if you comply with the USB HID class specification on the device side. LUFA makes USB coding fairly pleasant. an ATmega8U2 might be a little tight though, something like the Teensy 2.0 would be a bit more roomy, depending on how many bells and whistles you want to include
be advised that USB HID descriptors are a bit tangly to work with

>>1391888
>soldering
two words: John Gammell
shit's cash
>tip care
use tip tinner when the tip starts wetting poorly
don't leave the tip dry for very long
use a ball-of-turnings tip cleaner before welding a joint, or a moist kitchen sponge in a pinch

>>1391903
yeah, it's an imageboard
>without losing any current
it's not current you have to worry about losing, because at any junction in an electrical circuit, the current flowing in equals the current flowing out (Kirchhoff's Current Law). it's power. you'll be pissing away 80% of it as heat in the diodes
also note that mains ac voltage is specified as root-mean-square (oversimplification: approximately the average absolute voltage). peaks are actually higher by about 41.4%
also, diodes are rated for reverse voltage tolerance and forward current (do not exceed). forward voltage drop in silicon diodes is pretty much always on the order of a volt at their rated current (microwave oven diodes are basically just series stacks of regular diodes for greater reverse voltage tolerance). if you were using 10A diodes and had a really good night at the casino, you would need ranks of 10 parallel diodes, on the order of 300-400 of those ranks in series, plus a hell of a capacitor to smooth out the ac, and the voltage would vary inversely with the current the load actually sees fit to draw
and that's why we don't do that

>>1391909
>without losing any current

Ok then how do I get all that 240v 100a AC into my 48v 100a DC load, what about changing that AC to DC with lets say 100%efficient diodes and trying to squeeze as much of that current in there by also some how changing that 240v AC to 48v DC, what would YOU do?

>>1391914
Lets say without diodes or whatever you say

>>1391909
> and that's why we don't do that

There's lots of reasons :-)

1. Because of the heat, your diodes will be derated to, say, only 5A at some temperature (say, 100ºC). Kind of like how LEDs need to be current limited, otherwise they will "run away" as the apparent resistance will go down as it gets hotter.

2. We don't usually parallel diodes to get more current out of them for a related reason. One of the paralleled diodes will be slightly different (spec wise) and wind up conducting more current. When it does that it will get hot. GOTO 1.

3. In these strings of diodes, if you get a single diode failure, the whole thing might run away. In the case of an open, the other strings would take up the current. In the case of a short, the string would take on the current (with less total voltage drop). GOTO 1.

>>1391921
Ok understood!
Can you see this >>1391919 >>1391914 please, I’ve been having a hard time figuring out how to do something like that

>>1391914

Just use about 1.5 miles of 1 AWG copper wire. Should be around 4 tons of it.

>>1391914
brute fucking force, probably. a yuuuge transformer, followed by four yuuuuuuge diodes, followed by a yuuuuuuge capacitor bank. just like the old-style unregulated wall-warts but scaled way up, made with square bar instead of enamel-coated copper wire
also those diodes would go on a big ass heatsink because 0.6V * 600A ~= 360W of pure heat loss. maybe active cooling would be a good idea
maybe I'd just call up the local telco and see who they use for the similarly dimensioned power supplies in their central offices

>>1391927
Ooooooh what?! How do VFD/VSD do it

>>1391928
and because I'm sleepy af, the bottom two diodes need to go the other way. which, by the way, means they get a separate heat sink, because high-current devices like that often use their mounting surfaces as a terminal

>>1391928
WHAT!?

>>1391928
Big diodes/thyristors like that exist. DC arc welders, and high voltage DC transmission, and battery chargers for example. Pretty commonplace, actually.

The transformer is going to be huge. Is now a good time to discuss "duty cycle"? — a small transformer will burn out. For continuous duty, your transformer will be roughly 100 lb at 60 Hz.

What they do nowadays is rectify the mains, so you're getting 340 V DC. Then they switch it at, like 1MHz, and they can use a comparatively tiny transformer. But the windings are very special. To carry the current at that frequency, the primary winding is actually many insulated strands in parallel. This is because of the "skin effect" where high frequency current only travels on the outside of the conductor. Fascinating, eh?

>>1391938
What bro, skin? Are you talking about VFD’s

>>1391948
No, but I guess that's similar. Re-reading what I wrote there, you're basically looking at a DC arc welder. There's the brute force "tombstone" welders, and the smaller/lighter switching welders.

>>1390062
>Resistor code "Black"
That is a pretty expensive piece of wire.

>>1391951
0Ω links are frequently used on SMD boards as jumpers across traces for single or 2-sided boards, but are somewhat redundant for through-hole PCBs.

>>1391670
Ya.

>>1391951
Easier for automated assembly machines to pick up, so for single sided boards where there aren't many links needed they can be the cheapest choice.

>>1391853
0.5A barely keeps the phone on. It's 1A for slow charge and 2.4A for fast charge.
Some battery charger will take whatever current the charger they're plugged in delivers (because their regulator fucks up or because there wasn't one to begin with), so it's possible to explode a low-drain lithium battery by using the wrong phone/tablet charger.

Yo
How do I get the go go juice in this spinnatron?
It's brushless and I want to slap it either on a kart or bike
Do I have to build an esc or are there any I can buy as is?

>>1391993
This is the "pinout"
Black -> pink = phase 1
Black -> beige = phase 2
Black -> grey = phase 3
2 red -> 2 red = unknown

>>1391994
The 2 extra wires go here
I'm thinking they're either for measuring the rippums or something for the stator
The entire chassis is marked as ground, which I thought 3 phase didn't need

Say I need a +5,0,-5 voltage source for an instrumentation amplifier

I only have two different lab sources that offer just 0,+5 voltage

Would it be okay to connect the ground of the two different lab sources and use them as a -5,0,+5 source?

>>1391992
No I meant 0.5A at mains voltage, though actually it's closer to 0.15A.

>>1391996
Those red wires look like they're going to a hall sensor or perhaps even a feedback solenoid.

>>1391997
Depends on if they're isolated or not. Throw a voltmeter from one 5V to the other's 0V to see, though it's easy to imagine a voltage floating. Best way to check would be to throw a 1kΩ resistor in between them and see if there's a voltage across it, since the 10MΩ of a DMM could easily allow for some capacitive floating voltage.

Another way to check is to measure continuity between the pins of the PSU's power socket and the 0V output.

If I were you though I'd crank up the PSU to 10V or more, voltage divide myself a ground, and buffer it + capacitors.

Here's a question.

I have this motor from the US and it is currently wired for Low Voltage.
I need it to be High Voltage for 240v Euro currentcy.

If I change positions of the T5 and T8 leads as per the label, will it be in High Voltage or have I misunderstood?

>>1391951
but that's how they know you're a real pro

>>1392084
you have misunderstood. on either voltage, swapping T5 and T8 just makes it run backwards
follow the high voltage wiring diagram in toto

>>1391938
right right, I just didn't feel like designing a 24kVA switcher for a casual at that late hour. is dI/dt=200MA into Litz wire territory yet, or would plain neat multifilar windings be enough?

>>1392085
>follow the high voltage wiring diagram in toto

I'm a bit lost on where the P2 on the High Voltage side is supposed to go.

>>1392088
Nothing I'm guessing, though that would make it somewhat odd.

Any idea why my instrumentation amplifier is so noisy?

It's an INA128P

First pic is the measured signal, 2nd pic is the same signal through the instrumentation amplifier with Gain=1

I'm fine with the slew rate restrictions but this noise is like 1Vpp, fairly unacceptable I'd say?

I'm using +-15 V supply, connected 10 kohm to ground on each input, Vref is on ground, Rg is not connected to get that Gain=1.

>>1392088

one easy way to go low-voltage to high-voltage is to rewire the coils from Delta to Wye. my guess is P2 is the now-useless neutral wire.

>>1392099
breadboard or chapter 10?

>>1391993
this guy here again
can i run this thing as i would a bldc motor?
checked everything and the 2 red wires are some hall effect rotation sensors and it seems to generate voltage if spun
am i wrong in thinking that to generate any voltage it would need a moving magnetic field and thus that there are magnets inside?

>>1392132
Yeah it's on a breadboard. What's chapter 10?

Anyway I have found the noise to be linked with the power supply, now I'm using a different one and it's much cleaner, although there are some non-linearities when switching that I can't explain

>>1391469
http://www.ohmslawcalculator.com/555-monostable-calculator

>>1391469
>>1392151
Also you should buu some cheap 7404 chip to invert the input since 555's are triggered by the falling edge.

>>1392153
Nvm there's a pullup resistor in the circuit already

>>1390062
Could someone help me with creating a guitar pick up at home, like coils and components needed

>>1392149
>chapter 10?
TI datasheet, layout recommendations.

>>1392089
>>1392109
I considered it being a redundant wire, but then saw it was categorized under "insulation".

What does it mean?

>>1392254

it means you should insulate the bare end of the wire with tape, heat shrink, or a wire nut; not leave it free to touch anything.

Just bought this puppy. How'd I do? I'm trying to learn the basics from scratch. Got a couple books too but haven't started them yet.

>>1391027
Li-ion like THESE? I will run some experiments on some silicon sealant and hot glue today then get back to you. I was hoping someone might know about 'conforming' electronic sprays like those used on military and automotive PCBs.

>>1391680
These are material actuators, when heated they contract with great strength. Going to make an assistive Exo-suit out of them.

>>1392316
Assuming you mean conformal coating, it's just a thin waterproof clear-coat added to PCBs, and doesn't have any structural or filling properties. Conformal coating would be too rigid for this purpose. There aren't many coatings that would work and still allow access to heat the wire inside them, even if thermal stress wasn't a problem. Silicone is probably the best way to go for now, it should be possible to coat the actuator fairly thinly.

>>1392316
Those Li-ion cells are dangerous. The highest capacity cells on the market are Sanyo 3500mAh, or I think there might be some Panasonic 3600mAh, so 5000mAh is a bold-faced lie. Not just a little over-rated, but flat out wrong. No telling what other specs they'd lie about, like max draw. And if you get them too empty, charging them again is dangerous.

Best bang for your buck is Samsung 30Qs from the LiitoKala official stores on AliExpress. Maybe $3/cell or so.

>>1392316
>Li-ion like THESE?

These are ultra-fire brand, they are low drain (1A or 2), and are known to explode when used at high drain (like vaping large nicotine clouds).
There are lithium 18650, same size just a different wrap, that have 20A continuous rating and 60A in "pulse". Obviously, they have a smaller capacity. (also note : there are many fakes in the market, many assholes rewrap cheap low drain as expensive high drain.)
Try not to be in the news as the idiot who blew up his because he misused a battery.

>>1392316
Wait, you're saying >>1390925 isn't a resisting wire for vaping? It looks like some twisted clapton whatever the name, pic related.

Adding to >>1392349
batterymooch (on FB and others, can't post URL) this guy tests batteries. It's intended for vaping, but you can use his results for your needs.
For a reliable cell seller, look at vaping subreddits' wikis/sidebars.

>>1392207
Someone help me please I need it so bad I can't effort buying one.

>>1392364
http://www.google.com

>>1392364
Get a strong deodynium magnet and wrap it with enamelled "magnet wire", the smaller the diameter the better. I made one with a 6mm*10mm magnet and 50 or so turns of 26-28AWG wire, haven't tried it yet but it should work. If you do use a small number of turns (i.e. less than a few thousand) you'll need to feed it into a preamplifier, but number of turns won't effect your signal:noise ratio, only the magnet strength and proximity to the wire will do that. Ensure that the magnet has axial poles, I spent too many hours trying to troubleshoot a pickup wound with a diametric-pole magnet, pic related.

>>1392387
I love you. You are the best.

Repairing a PSX controller (MadCatz 8026) that has a fucked up cable. I have shrinkwrap of various sizes, but I feel this needs a proper strain relief. The hole in the shell for the cable is about 6mm in diameter, the cable is about 5mm OD. Should I bother with a strain relief? What would be an appropriate style of strain relief?

>>1392466
I'd use strain relief, but one of those tight-fitting cable glands would only work if it's all insulated as one.

>>1392470
Yeah, I cut it back so it was all reinsulated. I just don't want the cable to get fucked again.

>>1390365
>the only drawback
you forgot pnp transistors

>>1392582

>>1392604
>pnp transistors
>2018
I suppose they're good for applications that dont require fast switching. ie all of ohm
>tfw still haven't brought to fruition my power supply project

I have a board with basically just a H-bridge (DRV592) on it

It uses a 5V supply and the output is differential

When checking for short circuits with my multimeter when the device is not connected to the power supply, everything seems fine

However, once I connect the power supply and test the device, it indicates there's a short circuit between the ground and the OUT- and OUT+ terminal,

Is this normal, is this just due to how multimeter testing works?

>>1392612
I'd try turning it on with IN+ set to 5V and IN- set to 0V and measure the voltage across the output as you turn it on, still with the conservative current limiting.

Testing continuity cannot be done when the device is plugged in, since continuity or resistance testing put a small current through what they're trying to measure and record the voltage across it, so your DMM could just be reading whatever voltage is across the component as a result of it being turned on. But check continuity between the two outputs of the IC when it's not powered up.

>>1392615
Alright thanks

>Testing continuity cannot be done when the device is plugged in
Should have known this, everything else works fine

I want to send a handmade gift to my bf (ATtiny85 and a bunch of other electronics components). Will it resist, or those xray may damage the device ?

>>1392643
>Will it resist, or those xray may damage the device ?
It has to pass by the Custom Office and xray, will it resist or those xray may damage the device?*

What's the difference between a 3 phase induction motor and a bldc?
Can I run my former as a latter?

Sup lads. I'm working on a little project for the place I live/work. We want to set up an automated irrigation system, for which I've purchased one of these: https://www.adafruit.com/product/997

It says I should wire it with a TIP120, which I don't have. Googling tho, it seems this is just a 'darlington pair'. i don't know much about electronics, but could I just construct a darlington pair (I have a bunch of transistors) rather than buying a TIP120? Any pitfalls with this approach? Here is the circuit diagram of what I am planning

>>1392649
oh, actually looking at the datasheet for the TIP120, it has an equivalent circuit. I have all these bits so I should just be able to recreate it right?

https://cdn-shop.adafruit.com/datasheets/TIP120.pdf

What kind of connector is used in pic related? I've been trying to find connectors like these that have 8 pins but I can't find any.

i'm hand etching pcb here, will tipp-ex work as an acid resist? i tried black permanent marker and it just flakes off.

>>1392648
Technically you could run one as the other, provided you drive it correctly. The distinction to make is that an induction motor is asynchronous; the magnetic field in the squirrelcage slowly rotates in the opposite direction to that the rotor is spinning. The net effect is that while the magnetic field stays perfectly in sync with the switching electromagnets, the rotor itself moves a little slower, depending on the load. I believe this makes them harder to stall than a BLDC, not to mention easier to start and drive.

To run an induction motor as a BLDC you'd first need to ensure you're putting enough of a voltage across it, they're probably made for mains and running them even at 48VDC will result in a severe lack of torque, if it even gets up to speed, which is unlikely. But you won't need any feedback to run it, meaning you'd just need to supply it with 3 out-of-phase square waves (preferably with filtration), probably ramping up in frequency. A frequency ramp isn't necessary if you're running it at the intended voltage. Might struggle finding the right 3-way H-bridge IC though.

>>1392652
A BJT transistor has a current amplification ratio, emitter_current = hFE * base_current. Putting two in an arrangement like that squares this ratio. That circuit is bad because there's no base resistor to limit current out of the microcontroller, and the valve won't actuate on 5V, and there's no freewheel diode, and that it literally shorts Vcc to GND. A MOSFET will do the same thing as a darlington without requiring any current from the microcontroller. Pic related will work, provided you pick an appropriate MOSFET.

>>1392645
They'll be exposed to more radiation in flight than by the scanner. Unless you've got any undeveloped film, animals, or cameras currently filming in the direction of the scanner, all your belongings will survive just fine, including hard drives of both varieties.

>>1392666
Got any nail polish? It sticks without mercy.

>>1392677
sadly no.

>>1392673
I dunno if it's a squirrel cage
It doesn't cog noticeably, but works as a generator, which to me seems like it would need a proper stator w/ permanent magnets for
It's rated for 600w at 190v 2a, off a quick calculation that would be ~56 18650s IF I can find an esc to drive it with

>>1392607
power supplies are a pain in the ass.

>hey, let's make a portable power supply
>well it can't be a buck, guess it has to be a buck-boost
>wait let's charge the battery from the output, better make it a 4 switch buck boost
>voltage loops suck, let's add a current loop
>but peak current's bad for light loads, let's do average current
etc etc etc until the thing dies from complications. i think this is a common /diy/ disease.

>>1392694
>but works as a generator
By itself? An induction motor has to have a magnetic field induced to begin with to act as a generator. I'd advise against throwing a bunch of li-ions together to run an induction motor, since you'd only need to run it off DC if you were going for portability, while induction motors are heavy and likely overpowered for your purpose.

>>1392708
i know what you mean
I just want it to have a buck preregulator to keep its voltage at least 5V higher than an LM 317 which is helping to drive transistors for increased current(and not just the 317) and then i want 1mV precision. digital readout for current and voltag. 100W total.

>>1392677
Thank you for the information!

halp

>>1392738

>>1392089
>>1392109
Motor starts up and works fine now.
So far so good.

thanks for the help

>>1392654
That looks proprietary.

>>1392654
Typically the "connector" is just some pads on a PCB, while the other side is more connector-like block of spring pins. The plastic frame around the contacts might be proprietary.

>>1392677
I'm using 200g 98% ammonium persulfate in 500ml of water and it seems to be having no effect after an hour on a copper pcb, is this normal? I added so much to the water it is no longer dissolving. where am I going wrong or was I conned by the ebay supplier?

>>1392673
Cheers, exactly what I ended up doing, after researching and actually learning a bit about what I'm doing. I put a 1k resistor in series with the base of the MOSFET as well, since some people seemed to suggest it's worthwhile. Tested the valve earlier and it worked a treat.

>>1392807
the series resistor is useful in cases where you're switching the fet at any appreciable speed, because you're shorting the output into a ~3nF capacitor for up to a microsecond. i don't think you strictly need it here but it can't hurt. what you do want though is a pulldown from gate to source. your atmega's pins are tristate on powerup and don't have a defined positive or negative leakage so it's possible for it to trigger the fet before the code sets the output. if that's not happening it's probably because the gate capacitance is saving you, but it won't always.

>>1392811
Ok, thanks. How would I go about calculating the resistance needed for the pull-down? VIL and IIL values for the ATMega, right?

Rmax = VIL(max)/IIL = 0.3 / 1*10^-6 = 300kOhm

So use something like a 150kOhm resistor?

Been a programmer for years, discovering electronics feels similar to when I was learning programming for the first time.

>>1392654
the battery side is probably just a pc board or flex circuit
flat-tipped pogo pins would mate with them, if you can build some sort of assembly to hold them in place

>>1392686
sharpie also sorta works, with a fast enough etchant

>>1392851
according to the datasheet, the ATmega's internal pullups are minimum 20kohm, maximum 50kohm. when undriven, your pulldown would be the bottom half of a plain old resistive voltage divider, so the upper limit of your resistor is that which produces a divided voltage below the Vgs(on) of your FET. when driven, the lower limit of the pulldown is set by the Ioh of the ATmega pin, which isn't specified as such, but 10mA is a fair and conservative assumption. assuming 5V operation, if you connect the gate to the output pin and use your 1kohm resistor as the pulldown, your undriven voltage is ~0.24V and your driven current is about 5mA, which is fine. if 3.3V operation, your undriven voltage is ~0.16V and your driven current is about 3.3mA, which is also fine

>>1392716
What a load of nothing
Why did you even bother typing that up
Of course I'm not taping a bunch of lipos (lifepo, actually) to a fucking triphase and hope it works out
It's small as fuck and revs to the moon I want to slap it on a bike, obviously I can't ride around with an extension cord like a fucking Eva

>>1392851
Since you're trying to prevent the mosfet from turning on, the relevant voltage would be the minimum value of VGS(th). In principle, you should also add the mosfet gate leakage current to IIL.
Usually people just pick some nice round value like 10k or 100k. If you go with 10k and the gate resistor is 1k, you should pull the processor pin down instead of the mosfet gate to avoid dividing mosfet's drive voltage.

By the way, IRF520 isn't really meant for 5V drive. If you check the datasheet, it says it might need 4V to conduct just a little (250µA). Even the typical curves say that the mosfet is capable of switching only 2A with 5V drive. This might be enough for your solenoid, but a logic level fet would be a more proper choice.

>>1392868
The internal pull-ups are not enabled by default. ATmega's pins float before you configure them.

>>1392870
2A is definitely enough for the solenoid. I'll see if I have any other MOSFETs lying around but I might be shit out of luck.

Just to clarify, by '5V drive' you mean 5V to the gate right? Cause the VIN from the Arduino is 9V (actually no longer using a Nano, I'm using an Uno - the barrel connector makes my design a lot simpler)

>>1392877
>by '5V drive' you mean 5V to the gate right?
Yeah. VGS = 5V, to be exact.

Why the fuck atmega's spi brokes when i set SS pin low? It's configured as output not input.

Datasheet (page 165 is about SS pin): http://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-8271-8-bit-AVR-Microcontroller-ATmega48A-48PA-88A-88PA-168A-168PA-328-328P_datasheet_Complete.pdf


SPCR = (1<<SPE)|(1<<MSTR);
DDRB |= (1<<DDB2)|(1<<DDB3)|(1<<DDB5);
DDRB &= ~(1<<DDB4);

PORTB |= (1<<DDB2);
for(int i = 0;i<10;i++){
spi_send(0xFF);
}
PORTB &= ~(1<<DDB2); // after this line spi is dead


>>1392851
anything two orders of magnitude over your series resistor will do, so i'd just throw 100k in there. even at 1M leakages shouldn't give you trouble.

>>1392964
Dunno, but maybe it checks the pin direction when you write the the SPCR register. Try writing SPCR after setting DDRB.

>>1392869
You don't really want high revs on a bike motor, but rather a bunch of torque, but that's neither here nor there since it's an induction motor.

I wasn't implying you'd use a stack of li-ions without some sort of speed-controlling H-bridge and such, just that regardless of your battery voltage you'll need to switch some high voltage at some frequency for the induction motor. Going with a ~24V battery and boosting it up to ~100V before it gets switched is probably the most compact method, but it's still hardly ideal. Switching it before the boost converter may be possible. I'd recommend rewinding the motor more coarsely if you want to use it on batteries, but for the hassle it's probably not worth doing over buying a BLDC and saving the induction motor for a diy belt-sander or bench grinder.

>>1393018
>but rather a bunch of torque
That's why e-bikes usually have some kind of reduction

Does anyone on here know anything about BIOS flash chips? One of my friends who has a bit too much faith in my limited electronics repair skills brought his somewhat expensive laptop that doesn't want to start (still charges but absolutely nothing happens when the power button is pressed) for me to fix after going to three different places which couldn't find anything wrong with it. After checking the obvious stuff such as looking for burn marks on the board, if the power switch actually works, and other simple stuff like that and not finding anything, I started researching the various ICs on the board to see if I could find anything that could cause the symptoms that the computer was experiencing but couldn't find anything. The only other thing that I could think of checking is if the bios was actually intact since the computer doesn't even boot, using a cheap ch341a flasher.
So here's my question: Would I be able to read the bios using the flasher if that specific chip is unavailable in the program, but one in the same series with similar specs is? The chip that I am trying to read is a Winbond W25Q64FVSIG but the program that the ch341a uses only lists the W25Q64BV.

>>1392312
It's neat because it gives you projects to do and is easy on the hands, but you'll probably go through it relatively quickly since it only teaches really simple concepts without going too in depth. At your age you may have wanted to get a bread board and some variety pack components off of ebay or aliexpress since it's way cheaper and way more versatile as well as pirating some of the text books in the OP, but at least you'll have something to gift to younger relatives when you're done with it if you don't learn anything.

>>1393059
Hub motors do not as far as I know, you can drive BLDCs with plenty of poles quite slowly with plenty of torque. Just look at stepper motors.

>>1393018
>>1393155
17500rpm redline on the spec sheet
Driven 1:1 to a 17 inch motorbike tire that is more than 3000kmh, you fucking cretin
Of course I'll run a reduction, you mongospastic
Either a 2 stage Belt to chain countershaft or a massive rear pulley

>>1393142
most large flash chips use the same command set. pretty sure you'll be fine

>>1393162
I said hub motors, you know, these ones. The frame-mounted ones usually do rely on a chain reduction, but I think the hub motors are the most common these days, so I was just refuting your "usually".

>>1393142
probably close enough.

>>1393187
You said a bunch of inane shit to sound knowledgeable

>>1393162
What spec sheet are you referring to?

Direct drive hub motors are pretty common.

>>1393280
Quit airing your teeth

Speaking of motors, thoughts on axial flux?
https://electrek.co/2018/05/03/axial-flux-electric-motors-more-ev-power-smaller-package/

>>1393335
Saw them mentioned a year or so ago, they look pretty promising for motors in strange packages. In that instance I think I was seeing how plausible having a motor inside a rollerblade wheel would be. For personal reasons.

>>1393333
wat?

How's this for an automatic overcurrent circuit? RL is whatever load it's connected to, while Vswitch, Rswitch, and Qswitch would be replaced with a tactile button. The zener diode is less than ideal, but I don't think replacing it with a 3.3V linear regulator would be difficult. The LED turns on when the FET has latched off from overcurrent. I could equally build one for a positive voltage rail as well as the negative one, in the case I've a ground in between the two well.

>>1393424
not bad, but you could also replace the comparator with an open-collector output type
also, hold my beer

>>1393561
nm, this doesn't actually work

>>1393424
other considerations for your circuit:
increase the resistors in your latch by an order of magnitude or more, you don't need that much collector current
...unless you're driving the LED from one of the collectors directly, which you could also do
since you've got a 3V3 supply, maybe one of those nifty little "1G" logic gates in SOT-23 would suit this application. the 74LVC1G175 comes to mind

>>1393336
>how plausible having a motor inside a rollerblade wheel would be
I heard in some pro cycling races they sometimes check the bikes with thermal cameras because they can actually stick small motors within the wheel hubs to give boosts.

>>1393576
>this doesn't actually work
True, but the basic idea (latching the comparator via sufficient positive feedback) works.
The transistor FF could also be replaced with an SCR, either real or one made from two transistors.

>>1393424
It has one serious flaw: as long as you press the reset switch, the fuse is bypassed and your load gets all the current V1 can provide. You should also increase the comparator's reference voltage a bit. Now it is close to the worst case offset voltage.
You might also want to add some delay so that capacitive loads, motors, etc. start properly.

>>1393424
>How's this for an automatic overcurrent circuit?

it's a dumb circuit.
- the most typical overcurrent condition is a short circuit, which means the voltage you're using to power the circuit IS NOT THERE.
- having to reset the thing everytime is a pain in the ass. a much more congenial solution is one that actually limits the current to your set-point. (you know, the way they've done it in EVERY single lab power supply since the beginning of time itself.)

Had to use a small gasoline powered generator yesterday that said Power factor: 1.0 on a label. What does this mean in the context of generators? I thought this term was only used to describe loads.

>>1393600

means the max. power rating on the sticker only applies to resistive loads.

can someone tell me where to find info on building microcontroller from scratch? doesnt have to be complicated, i just want more then fucking 4bit adder to understand some microcontroller/processor shit.

>>1393585
>works
the application calls for the trip state of the FF to be level-triggered and the reset state to be edge-triggered. since there's a 'free' comparator in the LM393 package, I used it as a flip flop in Pic related, which actually works

>>1393679
>>>/hard/
also read https://www.xilinx.com/support/documentation/application_notes/xapp213.pdf which is a user manual for a super basic 8-bit microcontroller, sans peripherals

Is there any appreciable difference between chink push-in wire connectors and ones from a nice brand, like Ideal? I'm gonna pick up a few just for the parts bins, dunno if I should save a few bucks or not.

>>1393812
i wouldn't expect 100% conductivity test pass with them

>>1393576
I saw those gates a while ago when browsing through part lists, quite neat.

>>1393585
>as long as you press the reset switch, the fuse is bypassed and your load gets all the current V1 can provide.
I was assuming that the button would be pressed for a short enough time that the current wouldn't cause damage, but adding a capacitor in series with the button may work as an edge-trigger to limit that time.

>You might also want to add some delay so that capacitive loads, motors, etc. start properly.
I can't see how I'd make it not reactivate on button press in overload but still give a delay before tripping for starting inductive loads. It would be more for low-power breadboard circuits (mainly opamps and audio) to ensure I don't blow any of my opamp chips. The thing tripping off and having a LED on is so that I can rearrange the circuit to fix the short before turning it on again. If I do this then chances are I'll want both rails to trip open when one is shorted, which will require a bit more thinking.

>>1393592
I could easily fix the lack of a stable power rail with a diode in series with the regulator and a (super)capacitor across the regulator such that the capacitor can power the latch off before it runs out. I think having a current latch makes more sense in this application for the aforementioned reasons, I'm messing with ICs, not high-power devices. Chances are I'd be running this off a rectified transformer anyways.

>>1393812
>>1393815
Looks like it doesn't really matter, on the ones I care about getting, Lowe's beats AliExpress and Amazon. $0.07/connector versus maybe $0.09 and $0.13.

Hello. Not long ago I made a portable speaker from DIY components. It works nicely overall though I have some issues. Namely, speakers make quiet thudding sound when turned on and loud whistling sound when turned off. I used 150W step up module for adjusting voltage up to 16V and 4A. Amplifier is PAM 8610 with two 4 ohm speakers. Please see scheme attached. Have I made a mistake somewhere (with capacitors capacity etc) or could it be component issue (I suspect step up module)? I used the same scheme but with tda7297 amplifier, there were no similar sounds.

>>1394013
Sorry guys, here is the correct scheme (I mismatched capacitors polarity, sorry). The question is the same.

>>1394013
Perhaps a large capacitor in series with each speaker would help, that or a small capacitor in parallel with them. A small capacitor across the power rails (in addition to the existing large cap) and/or a choke in the line going from the step-up module to the amp might also help. Have a scope to put across the speaker and rails to see where you get a spike?

>>1394016

there's a lot that isnt clear on your circuit, so it's hard to diagnose the problem.
- the chip is rated for 7-15V, so why are you putting in 16V? you can get rid of the booster, which will eliminate one potential source of problems.
- how is the volume pot connected? it's supposed to provide a DC voltage to the chip, but in your drawing it's just floating in the air.
- what the fuck are the two caps at the bottom for? are they the audio inputs, or the outputs to the earphone. if they're inputs, the caps seem way too big, which might cause the popping at switch ON, coz they'e slow to charge. once again, they're just hangin in air, so it's unclear.
- the speaker outputs are differential, so there is no common ground between speakers. if you try to use a 3-pin earphone jack, then you'll have to connect the speaker grounds together, which is probably bad for then amp. since that part is also hanging in the air, it's unclear.
- the caps at the bottom should have + up, so your first drawing is correct but your corrected drawing is incorrect.

>>1394041
No oscilloscope, sorry, but thanks for the advice. What figures can you recommend for parallel capacitors for speakers.

>>1394043
Thanks for the detailed reply. Here is a picture of what I used as a base.
My bad with the booster, I tuned it on 15V actually, for highest power output of the amp. You are probably right, I could get rid of it, though the speaker would be a bit quieter then.
Is it true about the wrong polarity of the small capacitors between audio switch and pot? I assumed there are there to filter the noise but even when I tested the scheme without them I still heard this whistling sound on turn-off.

>>1394051
I love how beefy modern amplifiers are for such small packages.

>>1394063
They are. I used two full range speakers from an old BMW e39 with this tiny beast. Though I personally prefer how they sound with TDA 2797, even PAM8610 is more or less suitable for them and the sound is really loud, especially bass and some electronics.

Here is the speaker itself, by the way, with a Kindle for scale. I used bassport to calculate inner volume and added several ports for better sound, though I cannot tell much difference between ports and open holes. Bass is clearly present, though. I will add some waterproof acoustic fabric later to cover it from splashes and dust.

I want to generate a sin wave at a low voltage (think 1V). Am thinking of using a simple RC + OPAMP oscillator like in pic

Do you guys have any other suggestions for low voltage oscillators?

>>1394091
Forgot to mention the frequency I am aiming for is sub 1Hz, probably ~0.2Hz

>>1394043
>caps at the bottom should have + up
Forgot to ask you, why should it be so?

>>1394016

1st of all, I think your problem is connecting the switch after the booster. I would connect it before the booster. These things have ramped turn-on , usually.
DO NOT connect the (-) sides of the speakers together, these are run as a bridge configuration, they should be left floating.
I can bet any money that PAM chip amps have turn-on thud protection. Check the datasheet to see how it works and IF it is implemented on the specific board you have.

>>1394076
>those holes

jesus

>>1394091
If you omit amplitude control, you'll have lots of distortion. Typically the output will be driven to clipping.
Wien bridge oscillator with a lamp or jfet amplitude control is pretty popular (analog) method for producing sine.

>>1394132
>Forgot to ask you, why should it be so?

because the L+R inputs are gonna be referenced to ground, or 0V. so you'll get 0V on the bottom of the caps, and some unknown voltage between 0 and 15 on the top side. so, obviously the + should be on the top side, coz it's likely gonna be more positive. a voltmeter reading across each cap will confirm this.

>>1394137
Thanks for the response.
>connecting the switch after the booster. I would connect it before the booster.
Do you mean I should move the power on/off switch between the step up and the amplifier? At the moment it is actually connected before the step up module and after the BMS. Or do I understand you incorrectly somehow?
>DO NOT connect the (-) sides of the speakers together, these are run as a bridge configuration, they should be left floating.
They are not connected together but soldered to "-" audio terminals of the amplifier, each on its own side. Shall I unsolder them 0_o?
Thanks for the tip about thud protection, I'll take a closer look on that.
Sorry everybody, I am a real noob regarding DIY electronics so I make a bunch of stupid mistakes.
>>1394149
Yeah, they are ugly but do the job. I planned to have some accidental impact protection for the speakers as metal grills on them are quite thin. Accidentally these cut-outs proved themselves pretty useful for strapping the speaker to my backpack.

>>1392349
>>1392341
Yeah I just got some cheap ones to mess with, but they barely hold a charge and output is disappointing. 9vs in parallel are good enough for now but I am making a note to look into these brands for when I go portable. I appreciate the suggestions, thanks a bunch!

Also no this is not for vaping, Google "MIT nylon muscle" if you are interested.

>>1392330
Thanks for the information! I ran some experiments with nail polish(too stiff), silicone sealant(melted) and hotglue(too rigid). I ordered some silicone conformal coating and will try again with hotglue as it was almost working.

>>1394091
Get the app note AND8054-D.PDF from
www.onsemi.com/PowerSolutions/supportDoc.do?type=AppNotes&rpn=MC33501
Status of MC33501 is 'obsolete', look for a different 1 volt op amp.
Pic: Simple Machines version of the 3 integrator loop, tested from 100pF (11.6kHz) to 1µF (1.17Hz); amplitude stabilized by (visible) soft-clipping.

am I fucking retarded or does this relay series not list a coil polarity?

http://www.te.com/commerce/DocumentDelivery/DDEController?Action=srchrtrv&DocNm=1308242_T9A&DocType=DS&DocLang=English

Why is TME not listed in component sources?

>>1394312
Many relays have non-polarized coils.

>>1394319
Never heard. OP is at maximum length, so adding shit means removing something else.

>>1394319
y tho
t.OP

>>1394366
Don't know actually but that's where most of the packages to my job come from.

Why do they call them poles and zeroes?

>>1394437
it's a ww2 reference

>>1394437
Because a transfer/network function can be written as a ratio of two (factorised) polynomials. The roots of each polynomial describe at what s value the function becomes zero z. So if on the numerator the entire network function will tend to zero when s reaches that value (a zero), and if on the denominator the entire function tends to infinity when s reaches that value (a pole). I'm guessing the term "pole" is describing the vertical asymptote. Of course a real network function never actually reaches infinity because s is purely imaginary while poles are typically real or complex.

For example:
A(s) = (s+8)/((s+5)(s+11))
Will have a zero at s = -8, and poles at s = -5 and s = -11, which corresponds to some sort of high-pass filter.

tried fixing my computer's front audio jack and im pretty sure i fucked up

i call that black spot ''solder black hole'', because whenever i put some in there, it vanishes

Where do I buy a new one and how do I know which one to get?

>>1394572
Scrub it up with some IPA and try again with more flux. Reflowing it with some wick might help clear it up if you've put too much solder down there.

>>1394576

I spend 2 hours total trying to disassemble the case(it had screws with no head, so I had to break some shit to get to the audio jack)
I also had to test all this shit laying on the floor because my room is too tiny.
My back hurts like hell, I am drenched in sweat even though it is 1AM here and cold outside.

Right now im using the audio panel on the back, so it is working fine. I don't even think that my cheap iron is good enough, tip is too large and it was forming some bridges, so I think i'll just get a new one since they don't look expensive.

>>1394588
It's cheap to make, but it's specific to the particular case design, so you're not likely to find one that matches.

I was using a lab software oscilloscope for some low frequency stuff, around 1Hz. Since I had the time-scale all the way down to 200ms/div across the full 10div screen, the screen only updated every 2s instead of showing the signal tracking across the screen (the signal was too irregular to trigger from). For not-triggered very low frequency purposes such as this, do all digital scopes have a similar problem? I'm thinking of getting a somewhat modern scope soon and wonder if they all have this problem.

If I put a twin-t notch filter in the feedback loop of an amplifier does that effectively turn it into a very high Q bandpass filter?

>>1394179
>>1394222
Thanks for your guys help. Should have also said that sine does not have to be perfect (so don't mind if waveform is too distorted) as all I'm doing is fading an LED on/off.

Had a dig through AOE 3rd ed, and did see the lamp configuration, very neat how it can give such low distortion.
Also tried simulating "phase-shift oscillator" with some luck, but did not like how "complex" circuit was becoming. So in the end I went with the "3 integrator loop" circuit, have managed to get adequate performance at 2V & 0.2Hz :D

Arduino projects are fun and interesting. There is a lot of info on youtube and parts online.

>>1394641
No, they often have "roll" mode, where the screen scrolls from right to left. Sometimes it is forced, sometimes you need to specifically select it.

>>1394661
The gain outside the center frequency would be 1. But yeah, you can do it. The real life performance isn't that great, though.

>>1394689
One filter (red trace) was pretty disappointing admittedly with only around 30dB of gain at 32kHz. Cascading two of them is nicer at 60dB at 32kHz with a Q of about 56.5, at least in simulation. I'm not sure how much this will vary due to component tolerances though.

>>1394695
>30dB of gain at 32kHz
Sounds like GBW limitation of your opamp. Use a faster amplifier.
But yeah, component matching limits the real world performance.

Can I test capacitors in-circuit?

>>1394712
Probably not.

I'd like to put a capacitor on the output of my power supply. I can do 24V on it but I rarely go over 12, but I do hit 7ish amps often. I've cooked a few 1F 25V salvaged caps, should I just buy a couple super caps and put them in series?

>>1394803
>1F
>salvaged
yeah those were probably 2.5V rated, m80
get a battery

>>1394674
with gamma and what not, maybe you don't really want a sine, and a sawtooth would do just as well?

>>1394894
For some reason a sine gives a nicer transition

>>1394211
Well, thanks everybody who advised me regarding DIY portable speaker. I figured PAM8610 actually has MUTE function - it is manual and is done via additional switch and two terminals on the mainboard. I added an extra button to mute speakers before turning the amp off and so far there are no thud sounds at all.
I also sewed fabric cover from some car woofer carpet. Now it is high time to think how to fasten this monster of a speaker...well, anywhere. Preferably to my bicycle backpack. Though it seems I'd better come up with some kind of a rack. Time will tell.

>>1395030
Here are some photos from the assembly process.

>>1395030
And some buttons and charger port placement.

>>1394803
As far as I remember you should (ideally) use 2000 uF per each watt and choose at least 25% bigger voltage of the capacitors. 25V is bad in your case as the system can output 24V, even if you do not use such voltage. Try 50V capacitors with suitable capacity, in your case 12*7 plus 10%, approx. 100W. You can try 0.2F capacitors for 12V or use 0.4F capacitors for 24V. Yeah, they will be pricey.
If possible, somebody correct me if I am wrong. Thanks.

>>1394712
No because they will give or take some energy from the circuit and this, in turn, will tamper with your readings.

How should i measure the resonance frequency of this induction heater with an arduino?
I connected a 1k resistor and zener in series between one of the gates and ground but couldnt get a clean signal for the arduino.

What should i do?

>>1395188
The frequency changes depending on what you're heating, but to give a frequency readout I'd just google "arduino tachometer". I think they typically run no faster than a dozen kHz.

>>1395188

forget the arduino. get a software scope program like Winscope. to protect your sound card, divide the signal so it's lower than 0.5V and use back-to-back diodes to limit voltage input to the AUX jack to 0.7V. (use a cheap external USB sound card if still worried.)
https://windowsreport.com/oscilloscope-software-pc-laptop/

if the signal is clean, you can use a software frequency counter instead.

>>1395223
I already have a program written that tells the frequency from 1 period so the changing frequency is not a problem.

>>1395234
>forget the arduino.
Why do you even answer?

>>1395188
got a scope?

>>1395312

Throw schmitt trigger and maybe some passives on an end of the main inductor and feed it into a digital input, I can't see how this is conceptually difficult.

>>1395188
>What should i do?
Think /ham/, not /ohm/. How do you probe a resonant LC circuit without touching it?

Yo
If I can't find a proper esc for my motor how dumb would it be to try and make my own with a raspi and some MOSFETs?

>>1395341
>raspi
A 555 or two is all you need as far as I know, maybe some comparators. Arduino/non pleb-tier micro would be easy, though hardly ideal. Plus the FETs of course.

>>1395341
What kind of motor?

RPi is definitely not the right tool for the job. Some kind of micro is more sensible.

>>1395346
This one
>>1391993
>>1395342
Well, a raspi is what I have in my hands, anything else I'd have to order

>>1395356
If you don't have any appropriate FETs then you'll have to order stuff anyways, but I'm not sure how good raspis are at accurate high-speed switching, being such a high-level platform and all.

>>1390339
can you read what IC is this?

>>1395336
>without touching it?
Not him but why is this a requirement?

>>1395312
>>forget the arduino.
>Why do you even answer?

coz you're such a dumbass noob that you dont realize that, if the signal is dirty, then you cant trust what a digital counter says. you dont know what it's triggering from. but if you can see the waveform you can use your tiny brain to distinguish the fundamental frequency from the ringing and the noise.

>>1395414
Are there schmitt-trigger peak-detectors that only trigger on peaks above a certain magnitude? Because I kinda implied their existence in a lab report I'm writing.

>>1395419

never heard of such functionality available in silicon. tho, i've seen clever circuit designs that accomplish that. no references spring to mind.

>>1394588
Don't get a new iron, get a new iron tip.

Unless you can't change the tip, then definitively get a new iron (with a large and a small tip)

>>1395419

if you mean that the trigger levels are self-adjusting, i've never heard of such functionality available in silicon. tho, i've seen clever op-amp circuit designs that accomplish that. no references spring to mind.

>>1395434

You can detect peaks using an analog comparator, which is built into many arduinos. Whether or not it can capture all of the peaks depends on the frequency of the signal and the AVR clock.

If I want to make an EQ circuit for a phono amp, is there a reason why I'd use LR networks for the filters over RC or vice versa?

>>1395506
Large inductors suck and that's why they're avoided whenever possible.

What happens if I fuck up driving a brushless motor?

>>1395514
Just from a parasitic elements point of view?

>>1395520
You either fry the controller or the windings.

>>1395538
To clarify, the motor's specifications are a couple orders of magnitude over those of controller and battery

>>1395539
Then you probably won't be able to hurt it

>>1395527
Big, expensive, couple shit magnetically to/from their environment, high temperature coefficient, lossy, relatively low self-resonant frequency. Not necessarily all these simultaneously, though.

If you need large value inductors for small-signal use, it often makes more sense to use simulated inductors instead.

A coworker asked me to design a wireless switch for his compressor (240V US / 20A). Does anyone have any resources that will help me estimate the energy the TVS will need to absorb if the relays shut off at the worst case? Also, should I prefer TVS diodes over MOVs from a reliability standpoint? Any other advice on the mains side of this circuit is welcome.

I need to replace TX3401 in this diagram but the part is out of production. How can I find an equivalent transformer? I can't find a datasheet for 095-04574.

>>1395642
You aren't very likely to find a suitable replacement unfortunately. This transformer was probably specifically designed for this switching regulator and was only manufactured for the duration of the production run of the power supply. The odds of you finding some generic off the shelf replacement are low.

If you knew the core size, core material, and number of windings you could possibly wind your own but it'd be difficult and even with a datasheet that info isn't always there. I've generally found transformer datasheets to be pretty lackluster usually only giving physical dimensions, turns ratio, and sometimes leakage flux information.

>>1395642
prewound transformers that can replace the one in your unit are not likely to be available because there's so many different winding configurations.

if you don't want to replace the unit you can determine the wire gauge, turns count, pinout, and core type/size on the dead transformer in your supply and then wind your own from new parts.

>>1395648
>>1395651
damn. I guess I'll keep an eye out for other broken units with this circuit and see if I can salvage one from there.

>>1395654
That's probably your best bet. I'm actually going to rescind my advice about winding your own transformer, not that I really recommended it to begin with, since the schematic states components with the X designation are critical safety components which probably means that transformer deals with high voltages so if you wound your own you'd need to be absolutely sure what you're doing when winding it to ensure proper isolation so high voltage on one winding won't arc over to another. You'd need a to test it with a insulation tester.

Does this have something to do with a CRT? There's a terminal that runs to a degausser.

>>1395660
yes, it's for a Zenith C27A24T. It makes a rising whistle when plugged in and by listening through a plastic tube I found the transformer to be the loudest part. I thought it might have been a cap at first but they all look fine.

>>1395663
Transformers tend to make noise when they're under a high load. It could be that there is a short or arcing inside the transformer itself but it could also be some other component that has failed causing the transformer to see higher currents that it would in normal operation. Didoes are usually a good candidate for failure in switching converters you may wanna check that they're good. Just make sure everything is discharged first. You wouldn't want any nasty surprises.

>>1395668
I guess I'll keep probing around then, hopefully it is just a bad diode or something. I would have expected a short to blow the fuse though.

>>1395663
transformer makes noise with frequency, the magnetic field causes the core to vibrate. with age the laminations separate and it vibrates more and gets louder.

smps is something you do NOT want to diagnose unless you know exactly what you are doing. by their nature they are very dangerous, its not always obvious what is at a potentially lethal voltage wrt ground.
do not try to fix it when its powered.

>>1395695
The noise isn't a constant buzz like you're describing. It's a sort of charging sound that only happens when it gets plugged in. I don't work on it while powered. I work with power excitation systems at my job so I know mostly what I'm doing, just not smps specifically.

so I've made a bunch of 7 segment displays flash with an astable multivibrator.

Now I want to make the individual displays glow and fade in a cascading wave pattern, from left to right for example.
Something tells me this is significantly more complex than an astable multivibrator

what would I be looking for here

>>1395702
Easy: microcontroller + shift register
Hard: truth table, karnaugh map, explicit logic gates and FFs
What kind of pattern do you want?

>>1395731
I don't know how to describe it.

Imagine there's a single LED. It's powered by something whose output looks like a sine wave. It just rises and falls, like a microcontroller's PWM feature.
Then, if we were to do it with the 7 segment displays, they would rise and fall one after another, so it would look like a smooth wave.

I want to do it with discrete components if it's feasible, because I'm trying to do this to learn.

suppose we don't even need the wave to move left to right. I just want all of the displays to just fade in and out in unison. How would I do that?

>>1395736
>>1395731
For the "fade in and out of unison" one, it turns out I can do that using a 555.

I found this diagram, but it relies on a manual push button switch to charge and discharge the LED.

I know you can use transistors to switch. How would I use one to automate this pushbutton? A Capacitor that slowly charges?
Maybe another astable multivibrator?

>>1395737
nevermind, I'm going to have to use a transistor and a potential divider I think

>>1395362
an ESC's only medium speed, and surprisingly, they might not be too bad. the BCM283x chips have a support library that apparently includes drivers for a hardware waveform generator, which some projects e.g. nanoDLP have successfully used to control stepper motors, admittedly a slightly different and more tolerant kettle of fish. I don't see any sign that they're any quicker than any other linux SoC at reading feedback inputs, however

>>1395391
I think he's talking about a grid dip meter, which isn't exactly automatic. still, a non-contact method would avoid disturbing the resonant circuit. you could wrap a wire around the induction coil somewhere and call it a transformer, maybe

>>1395737
yep, add the astable circuit and use it to control a pnp transistor + base resistor which replaces the switch. then it's easy to add in the shift register and multiply the current regulators to get that wave effect you want
assuming single LEDs, but in a common current source arrangement, the more segments you turn on, the more LEDs the current gets split between, thus 1 will be brighter than 8. instead, I think you want a PWM switch on the common, whose pulse width is controlled by the astable/shift reg and RC. are opamps discrete enough for you?

>>1395750
the 555 circuit worked fantastically. Now I just need to get my hands on a shift register.

I painstakingly arranged this gif to show the effect I'm going for. The adjacent lights to the fully lit one aren't completely out, but still slightly lit.
Somewhat like old-fashioned cinema marquee lights.

>>1395737
Surely it can be simpler than that, you should be able to do it with a single transistor and maybe an extra diode.

>>1395829
Yeah I got the smooth fade working with a transistor and a 555.
Now I'm working on trying to get it to do this >>1395827

>>1395827

this has been done a million times before. you can google ''Knight Rider LED chaser" to find dozens of different solutions.

>>1395831
one way to do it:
the CD4017 is probably the device you're looking for. it's actually a counter with a 1-of-10 decoder built in. you'd just wire the 4 or 5 output to reset and duplicate your current controller 5x
another way to do it:
add a comparator that turns the next stage's charge transistor on when the R1/C2/R3 junction reaches a certain voltage. repeat as desired

>>1395857
>a fucking lolduino and a TO-220 regulator
how very educational about analog electronics. lurk more

What electronics part is this called?

What's the best way to drive 3.3v leds with 1.2v input? I had some stop up converters (MT3608) but they need at least 2v input.

>>1395874
joule thief will work below 1v

>>1395868
G, L1, L2 sound like 2-phase power (maybe live and neutral) to me, and perhaps X and Y are the coil inputs for it as a relay (since the holes are smaller), but the upper image makes me doubt that. Those are glass tubes with pins on either side? All I can think of is some sort of lamp or heater, probably the former since it's in a plastic enclosure. Run a continuity test (or better still an LCR test) on the pins? I doubt it's a relay+flashlight but you never know.

>>1395893
I should have mentioned it came out of an old telephone manufactured mid 70s.

>>1395874
there are ICs designed just for that purpose

>processing ADC data in python
>code is too inefficient
>keep adding more to it, keeps taking longer to run
>python has stopped responding
>it usually still completes the code after this so I'll let it run
>this time it runs a full 100% of a CPU core
>kernel task starts freaking out
>python now at 10% CPU
>quit python
>kernel task still running at 115% CPU
ehh I'll just restart and everything will be ok

>>1390883
Simulation tools are rarely if ever used for theory outside of classrooms in my limited job experience. The principals and theory are supposed to be known by that point

>>1395960
Well that was a nightmare. Restarting didn't help at all. I'd almost got the inverse FFT of my filtered data, but it serves me right for using a 114MB txt file of data. Sample frequency doesn't even make a big difference in this case, I could have easily dropped it below 10kS/s.

I've interfaced a ball mouse 3 pin photointerrupter to an arduino and used a 600 ohm resistor on both legs, the middle pin tied to 5v. I have had 3 photointerrupters fail after a few weeks, dc voltage from the output pin rising to 8volts, higher than the source voltage. ac voltage indicates normal. what is happening here? why would it give out ac?

>>1395356
That's not gonna be easy to drive without just buying shit. You'll need at a minimum a reasonably high voltage DC source, ideally around 250-300V. Then you'll need a three phase MOSFET or IGBT bridge and gate drive circuit to run it, and a way to generate variable frequency PWM sine like waves to drive the inverter.

>>1395864
awesome, I have a cd4017 on hand, I can cancel my shift register order.
I think I'll be able to do the circuit by tonight, we'll see.

>>1395874
>What's the best way to drive 3.3v leds with 1.2v input?

pull one of these from your neighbor's yard.

What type of capacitor has the thinnest layer of plates? Im thinking it depends on the maximum voltage rating. But what sort of technology might have the thinnest layers?

I want to use them for microscopy experiments and i need a superfine regular structure .

>>1395984
why aren't you trying to find datasheets first?

>>1396171

Hi /ohm/, I bought a Microchip Curiosity board (16F1619) and I was wondering if I could just remove the microcontroler and put it on a handmade board, will it be ready to use ? Anybody with a website/pdf/lesson to see the path to follow

>>1396174
Thanks. Now i remember looking at this a while ago but for a different reason.

>>1396150
don't

Say I have a signal amplified by a bipolar instrumentation amplifier, in the range of -3 to 3 volts

How would I go about acquiring that signal using an ADC (integrated in stm32 uc) that uses unipolar 0 to ~3.6 voltage input range?

>>1396150
The heck is that? I'm not familiar with tube circuits so I don't really get the reference.

>>1396289

use voltage divider to cut voltage in half, then add a 1.5V dc offset. if you're super keen, you can do both with one op-amp.
ref.:https://electronics.stackexchange.com/questions/304939/how-to-add-dc-offset-to-a-sine-wave-so-from-2-5v-2-5v-to-0v-5v

>>1396347
it's an iconoscope camera of some kind. I don't get the caption though.

>>1396175
Yep, can just pull the chip out of the socket and stick it on any breadboard or whatever. The minimum you need to connect to it are the ground pin and the 2.3-5.5v supply pin and away you go. If you want to be able to program it on your board you'll want a connector for the ICSP pins.

>>1395962
>for theory
What is this supposed to mean?
There are plenty of situations where simulation produces good enough results and simulation is often easier and faster than tinkering with a prototype.
Some companies use simulators, some don't.

>>1396423
Thank you

>>1396451
This.
Companies also use hugely expensive professional software. Not whatever garbage you're probably tinkering with

>>1396421
Well maybe "SNAP" because that's what cameras do when they take photos? Bit of a stretch. Can't really see how that thing handles the image signal though, there's just a single line coming out of the plate even though there would be hundreds of pixels on the plate itself.

>>1396494
Oh never mind, I think the electron gun only scans one pixel at a time such that each pixel emits a charge in sequence, and this sequence is preserved and fed into a CRT display with its flyback pixel scanning. Surprisingly simple way of handling images.

I can get my LEDs to work as photodiodes (without a reverse bias, just measuring with a multimeter and a small cap to eliminate mains noise) and are putting out 1-2V under full flashlight exposure, but my germanium and silicon glass-package diodes are barely getting past 10mV under the brightest of beams. Any reason people use these for solar diode banks over LEDs?

>>1396592
Your germanium diodes have tiny junctions and thus tiny light sensitive areas.
Your silicon diodes have their chips pressed between the electrodes, which prevent the light from reaching the junction area.
Your LEDs, on the other hand, have large junctions fully exposed to the user (since the junction emits light in normal use).

Silicon is used in most solar cells, because it is reasonably cheap and it is possible to make rather large cells that way. Solar cells made from exotic materials exist, though.

>>1396689
>>1396689
>>1396689
>>1396689
>>1396689

Would it be a dumb idea to use this to power a single (vintage) 3.2 ohm speaker?
https://www.amazon.com/KNACRO-Wireless-Bluetooth-Receiver-Amplifier/dp/B01EW6IJ1Y/ref=pd_rhf_se_s_cp_0_2?_encoding=UTF8&pd_rd_i=B01EW6IJ1Y&pd_rd_r=CPHJT15AECNATK45Q82G&pd_rd_w=PYUTJ&pd_rd_wg=1lDFM&psc=1&refRID=CPHJT15AECNATK45Q82G#customerReviews

>>1397055
new thread