/diy/ - Do It Yourself

>>1408236
this thread's digits brought to you in part by the AD8236, "the lowest power instrumentation amplifier in the industry"

I have some chokes here, how do I identify them?

>>1408242
Signal generator and oscilloscope?

Hey guys I’m tring to build a washing machine controller with a H bridge and an arduino uno r3, I want it to go high frequency does anyone know where I could get a free program?

>>1408256
I don't have a oscilloscope or a signal generator, only a multimeter and a psu.

>>1408276

only way to measure impedance is to put an AC signal across it, preferably a sine wave at high frequency, and a means to measure that voltage, so you're not equipped for the job, as your girlfriend has no doubt told you previously.

I want to put an Arduino at my coffee machine, so I can set it up to start the coffee some minutes before I wake up. But I don't know how I could feed the arduino, as the coffee machine works on 220v and the arduino works on 5v.

Is picking up a 5v PSU and setting it in parallel with the coffee machine, on the same wire a good idea? Won't shit explode? Noob question, I'm sorry.

>>1408302
>Is picking up a 5v PSU and setting it in parallel with the coffee machine, on the same wire a good idea?
should work fine

You know how to use a relay right?
By the way, how are you gonna do the timing with the arduino? I know it an be done with a clock module, but then you would be better of wiring a cheap alarm clock instead of an arduino.

>>1408325
you can use the arduino's timers but google says the crystal is accurate to 50ppm so that's up to a half hour drift per year.

>>1408325
Seems to be a better idea. I'll take a look into it.

>>1408331
if you use the arduino timer it will reset if theres a power failure
you could run it off batteries, but then you have to use a pro mini because the UNO is too hungry

this thing isnt very expensive
https://www.amazon.com/Century-Heavy-Digital-Programmable-Timer/dp/B00MVF16JG/ref=sr_1_4?s=lamps-light&ie=UTF8&qid=1529294002&sr=1-4&keywords=timer
but then there is no fun

>>1408337
>not using one of those DS1307/DS313x ICs to keep time

>>1408302
>not using an ESP8266
>not using a blister-packed ESP8266 device with an outlet already wired up to it
>not reflashing that device with NodeMCU and setting it up to query SNTP servers for the correct, accurate time
well, let's just say that's not the way I'd go about that

>>1408342
>meme arrowing your posts
stop any time

>>1408342
I wouldn't mind the ESP8266 if it wasnt shilled so hard

>>1408342
Why the hell would I want to use 2 outlets instead of one?

>>1408346
meh, it's a usable WiFi SoC with good community support and tooling, and uniquely dirt cheap, even as FCC certified modules. I'd be glad to hear of something better

>>1408353
excellent question

I'm about to try and wire up my dads shed, I have some basic knowledge of how electricity works, its a 20'x20' uninsulated ?aluminum? building
How fucked am i?

I'm if I'm looking to start my Associates in EE would these starter books help me out through some of it? I know electronics, but I've forgotten the equations and the names of parts due to not working in the field over the last 5 years. I'm more or less looking to do refresher and work on building small things until I can hopefully get back to working in the field when I finish the degree in 2 years.

>>1408260
You're not going to find a program exactly as you want, you'd be much better off learning how the language works yourself. It's not that tough.

I've got some LED strip lights with a motion sensor. They run off a 12V 5A DC power adapter. When the lights are off (but adapter is on), the adapter makes an annoying whirring/whining sound. Is there anything I can do about this? Some people suggest opening it up and coating the transformer with glue from a glue gun, but I'd be worried about it overheating

I'm happy to buy a better quality adapter but I'm not sure it would be any better

>>1408484
Eco-friendly hiccup mode to save energy and remind people to switch off crap they do not need.

>>1408484
Better quality adapters certainly are better, I've got a fair few of them and only my cheap shitty ones whine with no load. I'd just open up its enclosure, replace its initial rectifying diode(s) with small lengths of solid-core copper (or 0-ohm SMD links if you've got any handy), then have an external rectifier plus high-voltage FET that you use to switch the entire assembly. Might want a small capacitor across the input side also. Oh if you're switching the entire thing with the LED-strip's remote you're in the shit though.

>>1408378
i graduated in ME and got into EE by reading "electronics for inventors". i only used it to learn the basics though. the intermediate level topics i picked up through online self study and experimenting in multisim and on breadboards.

hello, I need to shut down the R6 5 amp load if something gets too hot and my apartment doesn`t burn. If I put a thermistor in the thing it can shut down Q2. (I haven`t bought a thermistor yet, so I don`t know the bias values). The problem is the thing will turn on back again when it cools. How can I make it turn off until I manually turn it on? I can`t use MCs because my pickit hasn`t arrived yet.

>>1408701
You may ask, why two transistors? And I don`t know. It just seems safer.

>>1408701
Q1 and most of the resistors do nothing worth mentioning in that circuit.
Since your load current is relatively high, you'd need a circuit with some kind of snap action to avoid the situation where Q2 is somewhat on and gets very hot. Well, assuming you dislike heatsinks. One way to achieve that would be to use a relay to switch R6 on and off. You could also use the same relay to switch the circuit's own power off so that it remains off after tripping.
Not that you can't achieve the same without relays, but relay version would be very simple.

>>1408771
I never used relays before. Actually I never used anything above 1 A before so I have no idea of what i`m doing. Could you draw a sketch for me?

>>1408701
this is a very sophisticated shitpost
anyway, use comparators instead. one to turn the MOSFET on and off, one to latch the temperature input to way too hot when it gets too hot

>>1408777
Thanks man.

>>1408242
>>1408276
Don't they have any markings on them? There's a couple ways chokes are often marked(usually a numerical value and an exponent, or just a part number), unless they're of the kind that aren't encased at all. However, if they only have a few windings there are equations that you can use to calculate the theoretical inductance given the number of windings, material of the core(if any) and wire gauge. I doubt you'd want to get into all that though, it's a real pain in the ass.

It's possible to run audio frequency signals through the choke using nothing but your PC's line out output, and measure AC voltage values over the choke with your multimeter and calculate the inductance from those, but that isn't really something an amateur should even attempt.

>>1408302
>>1408342
I would use one of those thermal carafe coffee machines that just shit out the coffee into a thermos pitcher and then shut off automatically. Even if it gets turned on way too early you'll still have hot coffee when you wake and there's no chance of the coffee machine's heating elements staying on for longer than necessary. It's not the most elegant solution but it is pretty much idiot proof. Just wire the "make me my damn coffee" button to an I/O pin on the SoC using something like a relay and set it to trigger the relay at whatever time you want and you can't even fry the SoC unless you screw up really hard.

>>1408366
Run the cables through PVC pipes, they offer quite a bit of extra insulation.

>>1408638
Appreciate it it, I'll look to getting that one.

>>1408366
>How fucked am I?
The fact that you have to ask is not a good sign, aside from that, I'd need a lot more information about your project, such as what country you're in, what you intend to power, etc..

>>1408378
Re-learn just a few things
>Kirchoff's laws
>how to make a basic power supply
>how to design a transistor amplifier
>fucking op-amps, how do they work?
>also logic circuits(and, or, not etc.)
It's all easy stuff but having a clear understanding of how the basic circuits work is the key to understanding everything else.
>>1408508
Listen to this man, coil whine is usually due to shit tier transformers. I would just modify the switch set-up so that the adapter gets switched off too when the lights are switched off, though.
>>1408701
>How can I make it turn off until I manually turn it on?
I'd use something that latches the circuit open and needs manual intervention to close it again. I like relays so I'm gonna suggest a SSR to break the circuit with a reset button to get it going again.

I want to add an M.2 SSD to my laptop instead of replacing the HDD with one. I couldn't find any documentation on what internal ports it has like an extra msata or an m.2 so I took it upon myself to take a look. I found what I believe to be an m.2 port (pic related) on the motherboard that isn't soldered and there is an empty space an even a screw hole to mount it.

As someone who has only soldered scarcely and at 0.1 inch pitch or larger, how hard would it be to solder on the connector. Also is it a good idea? Do you think the computer may ignore it even if I did add it correctly? Thanks in advance for any advice given!

>>1408804
I just realised I only need to make a sr flipflop. I feel so stupid.
>I'd use something that latches the circuit open and needs manual intervention to close it again.
that is what I said

>>1408808
>sr flipflop
I forgot these were even a thing since JK flipflops do everything they can and more.

>>1408813
SR only takes two BJTs

>>1408788
this anon gets it

>>1408806
unless you solder up all those other unpopulated components, which you probably don't know what they are and it's not even necessarily safe to assume are correct in the design, and then have the BIOS configure the chipset as required, you're not gonna get much action out of whatever you plug into it
I hate to buyfag, but you're better off to just buy an external USB enclosure

>>1408820
well shit, thanks!

>>1408817
But JKs come in very convenient ICs

>>1408826
but SRs come in very convenient and/or very smol ICs (some wiring or inversion may be required)

>>1408834
It would be fun to build a computer out of logic gate ICs

>>1408834
>(some wiring or inversion may be required)
And this right here is why I prefer older, all-American chips. You can find 555s and 741s RIGHT NOW that have the same pinouts as they did decades ago. But by God Almighty if it isn't hard to get some replacements for chips that were made fairly recently without having to wire them queer as hell. Especially when you have all the new shitty casings being made that force you to make those silly expansion boards just to wire them the all-American way.
>t. not even American, I just really hate having to wire things in a way that God didn't intend just so we can have smaller packages

>>1408836
>It would be fun to build a computer out of logic gate ICs

if by ''fun'', you mean tedious and infuriatingly hard, and for very little gain, then you are correct.

>>1408841
you have to wire a 74xx00 to get S-R FF action anyway. 6/10 rant tho

>>1408836
it kinda isn't. clock distribution sucks if you want anything faster than a 6502, as the minicomputer designers found. stick with Verilog

it's trying to tell me something

>>1408802
I'm in America, alabama specifically if it matters
And I'm going to be powering some basic power tools and some bench tools, such as a metal lathe or maybe a small 3d printer, it's going to be a fairly generic workshop for hobby level blacksmithing, carpentry, and glass blowing

How can I tell if something I'm de-soldering is soldered with leaded solder? How unhealthy is it?

>>1408984

if you can grok this diagram, then you're 90% of the way there. youtube has videos that'll take you to rest of the whey.

>>1408804
Whats the best book to learn transistor amplifier design in your opinion.
I was told Sedra/Smith was really good but people also use razivi(not sure if im spelling that right). I've never read art of electronics but the descriptions say it doesn't do as much math, but would it be worth it for intuitions sake?

>>1408994
Only relatively recent stuff (last 10 years or so) uses leadfree solder.
Do not lick lead-lead containing boards or components. It is also a good idea to wash your hands before licking them, if you have handled lead-containing products.

>>1409005
That's correct. AoE isn't very heavy on math, it's not a focused rigorous textbook. But it's still great and tries to instill an intuitive / practical understanding of electronics.

>>1408366
>I'm about to try
Do, or do not. There is no "try"

>>1409005
AoE is a very practice and synthesis oriented book, while Sedra's book and the other usual college books focus more on theory and analysis.

If you have some problems with illegal copying, there's a sample chapter of AoE available. It gives you a pretty good idea of the book's style.
http://artofelectronics.net/wp-content/uploads/2016/02/AoE3_chapter9.pdf

>>1409009
lol ok, I was more concerned about inhaling the lead fumes than licking the boards but I'll bear that in mind incase the fumes drive me to taste that sweet lead straight from the source.

Part of the reason I thought it might be leaded solder is that my soldering iron tip seems to have been melting itself, it's shrunk pretty significantly (+5mm) in the last 24 hours, although it has seen a lot more use than it did in the previous 24 years, so I assume that might just be normal wear?

On a related note, does this look like a decent soldering iron for a beginner, or should I spend a little more for something better? I don't really solder that often so I don't want to drop a lot of money on something I'm not going to use much. Would I notice the difference between this (15W) and an 18W iron?
https://uk.rs-online.com/web/p/soldering-iron-kits/7683573/

>>1409024
>(+5mm) in the last 24 hours, although it has seen a lot more use than it did in the previous 24 years, so I assume that might just be normal wear?

5 mm in 24 hours is not normal wear.

>>1409024
>lead fumes
Lead and its oxides are practically non-volatile at soldering temperatures. Inhaling rosin smoke (or smoke in general) is bad for your health, though. Lead-free solder is not an exception to that.

> it's shrunk pretty significantly (+5mm) in the last 24 hours
I'd suspect the tip is just a bit loose and has been pushed into its holder.
Typical reasons for tip erosion are oxidation (worsened by high temperatures) and dissolution of the copper core in molten solder. If the copper part of the tip is exposed, the tip is pretty much fucked, anyway.
If anything, leaded solder melts easier and allows you to use lower tip temperature. This should increase the tip life, instead of shortening it.

>>1409024
>lead fumes
Misconception, there is not a significant amount of lead in "solder smoke". The smoke itself consists of burning soldering flux, the inhalation of which can be expected to be worse than inhaling wood smoke but probably not as bad as inhaling turpentine smoke.

>>1408836
It's interesting stuff but takes a lot of dedication, there's a free MIT course on building a simulated CPU from NAND gates
http://www.homebrewcpu.com/
http://nand2tetris.org/

Is solid state relay same as mechanical relay, or does it have some of that gay shit like transistors where the trigger current and triggered current are sort of combined?

>>1408836
>>1408912
>It would be fun to build a computer out of logic gate ICs
You know what would be even more fun? Building a computer out of relays. Imagine all the clickety-clack.

>>1409147
>Is solid state relay same as mechanical relay
no
>gay shit like transistors
no U
(but yes transistors. mosfet or triacs typically)
>where the trigger current and triggered current are sort of combined?
input and switched current are not combined, they are optically isolated.

>>1409158
>>1408836
https://www.youtube.com/watch?v=z71h9XZbAWY
https://www.youtube.com/watch?v=n3wPBcmSb2U (money shot at the end)

>>1408813

I want to use old PSU as a power supply for my bread board because i am poor. The psu has a 12V branch that can deliver up to 15A.
Is there some easy way to add a know so i can regulate it between 1 - 12V ?

>>1409219
>know
knob

>>1409219
maybe with a buck-boost converter and a 555 timer to control the pwm, wired with a potentiometer to vary the duty cycle?

>>1409219
no
Pic related would get you close, up to 5A and a hair under 12V probably

>>1409228
don't forget the charge pump and the ampop
oh and the shot of black

>>1409229
no that would never work, a charge pump wouldn't be able to handle such high currents

>>1409228
What if added a switch that switches between wires that have a resistor on them? Each would be different and eat a part of the voltage so i could have say 6 wires with resistors that eat 2v, 4v, 6v etc

>>1409236
Yeah that would be the "easy" way, but those resistors will dissipate P=Vr*I power as heat, so if you one day decide to use all of those 15A your best case scenario is a resistor dissipating 2*15=30W as heat, which is a lot (the normal hobbyist resistors are rated for 0.125-0.250W). Even if you use a lot less current (say 0.5A), that's still "a lot" of heat.
The advantage of a converter circuit is that it chops the voltage and then averages it, so it's a lot more efficient.

>>1409248
Yeah but i don't really know how to make one, i am just learning stuff.
So i will just several resistors in series so the heat will be split between them, I also saw they sell some big ones so i could slap some aluminium on them as a cooler
or maybe do a voltage splitter where is send part of the voltage into the ground

>>1409250
Fair enough, build what you're comfortable with. You can find resources online though, so maybe a future upgrade?
https://www.onsemi.com/pub/Collateral/LM2575-D.PDF (this one's only 1A, but there are some schematics towards the end you might find interesting)
https://abra-electronics.com/voltage-regulator-modules/ps-dcdc-15-15a-adjustable-dc-to-dc-step-down-converter.html

>>1409236
your loads will vary in the amount of current they draw. E still = I * R, so also too will the voltage drop across the resistors vary. resistors are not a substitute for a voltage regulator! you would get closer to the mark if you were to use a string of power diodes and that tap switch, but you would still have poor regulation down in the milliamps of current
just buy the regulator module and save yourself confusion and grief. worry about why later

How to program a blank pic without a programmer or another pic? Lets say I can borrow a Memuino Uno

>>1409317
did you even web search first
http://rweather.github.io/ardpicprog/

Am i ever going to use more than 2 channels on a scope?

>>1409354
yes

>>1409324
thanks

>>1409358
so rigol ds1054z it is?

Does it matter if my tweezers are "anti-ESD"?

>>1409371
no. worry about esd when you've got a $100 part. i've fingered plenty of mosfets without issue.

>>1409371
Just clip an alligator clip on the end with a piece of thick copper soldered on the other end jammed into the ground socket.

would this work?
I'm really new to electronics
basically I want to trigger a 3v relay with an ESP but my board isn't putting out enough current. My solution is to use a capacitor to give it that extra kick which is triggered by a transistor.

Anyways, if I use this idea, would the LED on this diagram turn on when D1 sends out the signal?
Am I using the capacitor in the right way? I don't think I am for some reason. My brain is drawing a blank

>>1409376
grab 'em by the p-substrate

>>1409396
you need a larger capacitor than you have in your junk box. a farad or two *might* do it, no guarantees about whether any particular copy of any particular relay model will be okay with it
better to find a way to get enough power to do it right

>>1409396
>>1409396
>basically I want to trigger a 3v relay with an ESP but my board isn't putting out enough current.
Why aren't you just taking power from the PSU you're supplying your dev board with and hooking up a transistor as a switch that's controlled by the ESP's output?

>>1409425
jesus fuck that is so simple that I didn't think of that. i basically had it already set up like that. I'll try that and report back in a bit
The relay is a HK4100f

I'm on very limited internet (5gb cap/month)

I downloaded all the books in the OP, but which youtuber should I download from?
I can't download all that are listed in OP
I want only the most concise and useful videos
my knowledge of electronics so far is only the first 50 pages of Forrest Mims' book

>>1409383
That's not really how it works. If the part is at a higher potential then a sudden discharge toground could damage it just as much as a sudden charge. ESD grounding wires have around 5MΩ resistance.

>>1409371
ESD is a meme. Just discharge yourself to ground periodically. The only things you really need to worry about are microcontrollers and processors and stuff.

>>1409425
Works great!
Thanks for the help

>>1409163
>(money shot at the end)
tfw your computer sounds like a steam locomotive

>>1409473
>Works great!

it may work, but it's not as great as it could be. what you have is a high side switch which loses about 0.7V, so the relay only gets 2.6V. if you were to wire it as a low-side switch, you'd only lose about 0.2V so the relay would get 3.1V

>>1409163
>tfw your computer is almost danceable

fuck i hate how there isn't any electronics store here so i have to order all shit from aliexpress and always wait a month for it to arrive ;_;

>>1409499
what country are you in

>>1409501
No, i don't want to date you creep.

>>1409502
this isn't a LONDON moment, you might actually get faster shipping times than a month you spaz.
do you think professionals order shit from ali? fuck no.

>>1409488
I guess I'll rewire it to be high side.
This is my first time using transistors, they're pretty cool now that I kind of understand them

>>1409505
I mean low side
It's late

>>1408236

What do you guys use just for general-purpose, signal-level/low-current connectors?

I've got a stash of a few thousand DuPont connectors, but lately I've been looking for some wire-to-wire connectors and medium-current (say maybe 3-5A) connectors that fill the gap I have between the small stuff and the stuff I expect to handle 15A+.

The JST connectors look promising for wire-to-wire, though I'm having a little trouble finding sets that are just the terminals and housings, without the wires attached. The wire-to-board sets seem plentiful, though.

I'm planning on turning an old computer PSU into a desktop power source for projects and shit. What type of connectors should I use? I would prefer those easy to plug/unplug style bullet connectors but I have no Idea what they are called. I want to make a box with a ton of power output options

>>1409511
banana jacks? sure, that's very respectable

Is it safe to solder directly to a battery? Kinda worried about what happens when the terminal heats up

>>1409528
>Is it safe to solder directly to a battery?

Depends on the battery, but, unless it has solder tabs specifically, it's not a good idea. At best, you run the risk of damaging the cell if you take too long and it gets too hot. At worst, yeah, it "vents with flame".

Much better to use a proper spot welder, if you can be arsed to make/buy one.

Do I need a true RMS meter if I want to play with ~250W motors and drive systems, as well as audio circuits?
Also planning on getting a rigol, if it matters.

Anyone able to help me identify the names of these electrical components I pulled put of PCBs?

Do inductors have a minimum frequency at which they can operate?

I have a ~28 uH inductor wound, but when i measure it with an LCR meter,
it only acts as an inductor (~90ish phase angle, appropriate serial resistance and inductance) at frequencies 80kHz and upward

I thought inductors only have upper border frequency restrictions, what gives?

>>1409636
They don't, but if the measurement frequency is low enough, coil's resistance will be high in comparison to the inductive reactance and it will dominate the results.
While this shouldn't be relevant to your LCR meter, it is also easier to saturate inductors at low frequencies. That is, you need less voltage across the coil to force too much current through it.

>>1409528
>>1409529
The idiot proof way would be to use a battery holder, that way the battery would be easily replaceable as well.

>>1409528
>Is it safe to solder directly to a battery?

i do it all the time to Alkalines, Nicads and NiMh.
trick #1 - use a tiny grinding wheel or file to remove a small area of coating on the metal coz that coating often refuses solder.
trick #2 - use a reasonably powerful iron (i use a 35W Weller with a thick spade bit) so that it'll melt the solder in 2 seconds or so. that's not long enough to transfer much heat into the cell.
trick #3 - it's best to solder on a corner so there's a minimum of heat sinking from the battery.

>>1409635

>>1409669
>>1409635
Also, 3 looks like an adjustable inductor (ift coil), 10 might be another big ass diode, 4 some type of transistor or a trimpot?, 8 and 12 might be other capacitors, 6 maybe a resistor or another capacitor, no idea what 2 could be, maybe another inductor or an electrolytic capacitor? and 9 i have no clue.

Googling the inscriptions will definitely help (eg 14 should say the model number on the flat part, which if googled should get you the datasheet). #1 is a 5W, 8.2k ohm resistor. #5 actually says 1.5uF, etc...

>>1409648
I'm sometimes getting negative inductance values and phase angles, impedance is also all over the place at frequencies lower than 60kHz

Upwards of that frequency it's alright, up to 1MHz which is as high as I'll theoretically go

What could be the cause of that? I'm using a HP 4284A LCR meter

>>1409636
>>1409692
As >>1409648 said, at low frequencies the inductive reactance of the coil will be low, which means external factors like stray capacitance, or even the internal capacitance of the coil itself, may even push the phase angle to negative values.

>>1409669
2 - inductor
3 - adjustable inductor (tunable coil)
4?
6 - capacitor
8 - wire thru ferrite ( filter )
9 - resonator? (crystal substitute)
10 - diode 1n5188
12 - capacitor

brazilian mail (dis)service will deliver my dissipators never ever so i did my own.
>inb4 get out and buy one
the city I live, even though a big one has like 2 electronics shop and they have very little stuff.

>>1409714

>>1409715

>>1409717
it werks. Tested with a cob I damaged by accident. (It overheated and now the middle part is dark.)

>>1409718
Doesn't look very efficient since it doesn't have any cooling fins. You could probably improve the heat dissipation with next to zero cost by hammering copper nails through the bottom of the mug, then bolting on a plate of scrap copper to better distribute heat to the nails(probably better to solder it on if you have a soldering torch handy), then finally bolting your chip on the whole thing.

>>1409736
it has holes on the side, I could make a spiral fin out of a soda can though.

>>1409747
The damaged cob was fucked before I used the dissipator btw, it cools them really well.

>>1409747
The thing is, the main goal is to maximize the surface area of the heat sink and just adding holes doesn't achieve that. A spiral fin made of a can could work, but you'd need to attach it firmly to the base of the mug in order for the heat to conduct to it properly, and frankly that sounds like a hassle since you'd have to do the work inside the mug.

>>1409757
Thanks anon, I`ll see what I can do until proper dissipators arrive.

>>1409758
>>1409736
also scrap metal and parts are really hard to come by here in this city. there are loads of people that live off scrap collecting and drug users that scavange shit. I`m still strugling to find a ded PC with a psu.

>>1409528
>lithium coin cells
Not safe, no. But it is possible

>>1409700
>>1409700
Again, I don't get it, How can stray or internal capacitance be a factor at lower frequencies?

I can't find anything to support that claim on the internet

>>1409993
You could simply experiment by connecting resistors in series and capacitors in parallel with your inductor to see how the readings change.
Better check what other measurement options your meter has (bias etc.) while you're at it.

>>1409993
Because at lower frequencies even a fairly small capacitance can cause a larger capacitive reactance than the inductive reactance is, meaning the phase shift angle over the coil goes negative even though a coil is, in theory, a completely inductive component. Here's some example calculations I made using numbers I pulled out my ass. And that's not even taking into account the resistive component of the impedance, so it really isn't wonder if you're seeing odd results. What are you trying to accomplish with these measurements anyway?

>>1410000
I'll definitely be running more experiments

>>1410002
What would then the explanation for non-linear progression such as this be?

I mean I'm getting some "correct" measurements in these lower frequencies (1kHz and 10kHz seem fine-ish, as in correct inductance value and near 90 phase shift)

While other measurements (12kHz, 20kHz) give me things like negative inductance and -155° phase angle

>What are you trying to accomplish with these measurements anyway?
I'm using the coil for some eddy current testing and these frequencies are of great importance to me

How do I determine what power soldering iron to get between 15, 18 or 25 watts? I get that they have different temperatures, but what effect does that have other than taking longer to heat up the solder?

>>1410031

15 and 18 are too weak for regular work. 25 is the minimum for PCB work, 35 is minimum for wiring work.

remember, you can always dim down, you cant dim up, so dont buy weak shit.

>>1409993
>can't find anything to support that claim
Because it's largely nonsense in this context.

When you measure a resistance you first short the test leads and zero the meter if you can or else note the displayed value to subtract it from what you measure.

I have a C meter and an LCR meter. The only one I can zero is the C meter. When I short the inputs of my cheapo LCR meter it shows -17µH as L and 0.3Ω as R. With an open input ist shows 12pF as C.

When I connect 22pF to the LCR meter it shows 34pF. When I connect a 10µH choke it shows -7µH. When I connect a rather large loop antenna it shows 608µH which means it has 625µH. Connecting 4.7nF in parallel does not change the value at all.

Checking and correcting measured values that way is common sense knowledge among practitioners but maybe not for the resident memetronics experts populating this place.

Just graduated, and I never got the chance to take analog design electives beyond analysis of mosfet/bjt amplifiers.
Is this book a good start to learning some analog stuff?

>>1410105
Never heard of that text before, looks dry.

I'd suggest the Art of Electronics (2nd or 3rd edition).

>>1409675
>>1409709
Thanks very much!

I think the top right components (#4) with the cylindrical metal tops with three legs are called bell transistors.

>>1410045
>15 and 18 are too weak for regular work

Hurr?

I used a cheap Weller 15W from RadioShack for years before getting a soldering station. Given how often I've seen other people with that exact model, I'm guessing I'm not the only one, either. It worked fine for anything that wasn't attached to a heatsink (and some stuff that was) or fatter than 12AWG.

>>1409504
It's not that there arent any stores in the country but there arent any in the town and i would have to pay $5 postal fees which is very espensive for me when i make $3/hour
Not to mention that on ali every component is 2 or 3 times or even more cheaper that in the whittu piggu jew stores

>>1409511
Use proper binding posts so you can screw them onto loose wires.

>>1410121
One of them is a trimmer resistor and the other is probably a transistor, but all kinds of other shit uses that case too. In other words, read the markings and google them.

>>1410045
What are the benefits of higher wattage? Does it just mean the solder melts quicker and hardens slower? I've been using a 15W one so far and like >>1410128 says it's always seemed fine. If anything my main concern with higher wattage is that it makes damaging components more likely; my soldering skills are still pretty shit-tier.

Also any tips on de-soldering? I have one of those pumps and it helps a bit, but I was thinking of getting some de-soldering braid, is that stuff any good?

>>1410146

For an unregulated iron, it means the iron is physically larger and therefore capable of dumping more heat, quickly, into a part with substantial thermal mass/conductivity. In other words, you can use it to solder parts that would otherwise wick heat away from a smaller iron too fast. As a consequence to this, they're generally less appropriate for smaller work.

For a regulated iron, more power is simply better. This allows them to come up to temperature faster, and they're able to make themselves useful on larger parts that would bog down smaller irons. Only downside is that higher-powered models cost more.

>>1409499
maybe you should save up for a bit and build up some inventory of chinkshit common parts, although your options still suck for not so common parts

>>1410128
how'd those 0603s work out for you with the cheapie iron?

>>1410146
too low wattage slows down your soldering and increases the risk of overheating parts. an iron with enough wattage that holds a good temperature will help you get in and out quicker. I wouldn't even consider an unregulated iron in 2018

>>1410148
yes, de-soldering braid is good, but you'll also want to get some liquid and/or paste flux, not only to supplement what little's already in the braid, but as a general soldering consumable. you might find it helpful for wire tinning, SMT, connector soldering, and almost any soldering tasks

>>1410150
>how'd those 0603s work out for you with the cheapie iron?

The hell does that have to do with an iron being "too weak"? Trying to do small SMD work with one of those would be fighting with _too much_ iron, if anything.

Can you guys point me to some ressources, preferably suited for retards like me, that explain magnetism and all kinds of vectors and calculations around it? Because honest to god, everything I find is either only covering the basics or "here's a bunch of 20 characters long formulas, have fun", but nothing in between.

>>1410169
>Can you guys point me to some ressources, preferably suited for retards like me, that explain magnetism and all kinds of vectors and calculations around it? Because honest to god, everything I find is either only covering the basics or "here's a bunch of 20 characters long formulas, have fun", but nothing in between.

You're looking for simple vectors and calculations, but the basics is too simple, and the actual equations are too complex???

What are you working on, or planning to do, and what level of education do you have?

>>1410172
I may have explained that in a bad way. Let me try again.
First, I'm not working on anything, I'm learning this for university. Though, I'm also interested in this whole stuff because it obviously can be useful.
1. There's basic stuff like: You've got N coils with I ampere, what's the magnetomotive force?
2. Then there's stuff with equations that I can't even type out here, like: You have 2 coils wrapped around some materials in complex forms, all kinds of different parameters and positions, give me an equation for the vector of the B field on the xy plane for any given position.

I need something that goes from 1 to 2 preferably step by step so I can actually wrap my brain around it, because throwing a solution to 2 into my face doesn't actually help me understand all that stuff.

>>1410176

almost nothing magnetic has a simple model, except for an infinitely long straight wire, and very simple air core solenoids (meaning coils). ideal transformers also have simple models.

You should be able to understand those simple ideal forms and how the equations work. but anything more complex will involve ferromagnetic materials and hysteresis curves, or if you're looking at electromagnetic radiation then you have high level math do deal with.

magnetism is complex because it is inherently three dimensional, unlike electronics which can usually be thought of in two dimensions, but even then once you add in time-varying quantities and the complexity is unlimited.

Maybe you are trying to learn everything at once? some things take time to be absorbed, and some things are beyond my intelligence.

>>1410180
I've also already worked with hysteresis curves, but I wouldn't say I'm knowing what I'm doing there. I don't know, I'll just give it another try and see if I find something to guide me step by step. Maybe I searched for the wrong things.

Why would they do this?

>>1410181
This video helped me better understand how the various variables in magnetism play with each other: https://www.youtube.com/watch?v=a21zh-obKWg&list=PLxaGnte1Dq0lgNtfA9H5Hd_YDyjylThJJ&index=5
I already knew about most of these though, as well as electric circuits, so this was more a summary that put things together for me, ymmv.

>>1410188
Thanks, I'll watch it right now.

>The Post Apocalyptic Inventor
Well, he certainly has my attention now.

>>1410193
he has some pretty cool videos, the entire series about power converters is really good but it's a real shame he never completed it. I also watched his videos where he reused washing machine motors to make a small electric vehicle.

Another good one if anyone's interested is Andreas Spiess, though he's more about RF and low power electronics rather than electromechanical.

>>1410188

very nice video, but the guy who wants to calculate magnetic parameters will be disappointed to see that the video makes no attempt to calculate anything, and deals with generalities and empirical measurements, which is pretty much how you have to treat magnetic devices, unless you have sophisticated 3-d modeling software and accurate characteristics for your magnetic core, which usually are rather imprecise because that's the nature of ferromagnetic materials and permanent magnets.

>>1410169
Hyperphysics is a damn good resource for that sort of thing. Learning how to form the correct integrals is something I find pretty challenging, particularly if they're not line-integrals or aren't rotationally symmetric. Thankfully, often it's possible to simplify a situation to just a 2D representation, so long as you convert the current/charge densities volume>surface and surface>line and line>point properly. Noticing when the field in certain directions cancels is also useful, for which the right-hand grip helps out.

Now when it comes to getting to those complicated magnetic field calculations I find the best way to go about it (assuming there isn't an easy solution somewhere) is to use the magnetic vector potential and take the curl of it, since you can just copy the integral from the equivalent electrostatic potential case (swapping 1/ε_0 for µ_0). Note that I skipped that question in the physics exam yesterday so I might not be the best person to talk about it.

But if you're looking to put these equations/knowledge into practical diy use you might have a problem or two, since they typically rely on very high levels of symmetry, infinitely thin wires, and unity permeabilities/permittivities. In industry I believe simulators are used instead that solve these vastly complex integrals numerically.

>>1409993
In what ballpark is the inductance? With lower values you'll get LC resonant effects from parasitic capacitance at lower frequencies

>>1410202
>With lower values you'll get LC resonant effects
w = 1/√(LC)
He'll need high C and L values to get any low frequency oscillation. Low-frequency oscillation with stray capacitance would require a large inductor. For example, oscillation at 100kHz (not sure what you mean by low frequency) with a somewhat generous capacitance of 100pF would require 25mH of inductance, which is unusually large for most purposes, but hardly unheard of. 1kHz would need 250H with this capacitance.

>>1410201
With Hyperphysics you mean the Youtube playlist? Because the first video is a funny looking prof being angry about something.

>>1410210
No, I mean the website:
>http://hyperphysics.phy-astr.gsu.edu/hbase/index.html
Just google X + "hyperphysics" and you should get a pretty comprehensive explanation of what you're looking for, or just follow the tree.

>>1410217
Oh I see, thanks, I'll check it out. The prof is pretty convincing though.

>>1410148
>I was thinking of getting some de-soldering braid, is that stuff any good?

no it isnt. neither are plunger pumps. both work, but neither one make the job easy. if you want easy you need a special desoldering iron. there's the cheaper ones with a squeeze bulb, and the much more expensive ones using a real vacuum pump.

>>1410262
>not buying high-quality Japanese Goot-brand solder wick
Add some extra flux to it, even hand-woven pretinned copper wire makes great wick with a dob of jelly-rosin.

>>1410323

nonsense. when the hole is tight, or the pin is pushed against the side of the hole, no wick, no matter how good, is gonna wick out the trapped solder. but if you use a de-soldering iron, you can jiggle it while it sucks, removing solder from all sides.

>>1410323

nonsense. when the hole is tight, or the pin is pushed against the side of the hole, no wick, no matter how good, is gonna wick out the trapped solder. but if you use a de-soldering iron, you can jiggle the pin it while it sucks, removing solder from all sides.

>>1410383
You can do that jiggle thing with wick as well.

can someone explain to me how to design transistor amplifiers? I know how to analyse the circuits but I seem to be unable to close the gap betwen analysis and synthesis.

>>1410551
read one of those books on the OP

>>1410551
This depends on your goals. Shitty audio amplifiers using few transistors are easy and straightforward to design, but anything beyond that can get pretty involved.

If I use a LM338 or LM317 or something like that to drop lets say 40v to 20 or something like that, would the current that the 20v is provided at be higher than that of the 40?

>>1410182
"because fuck you, read OUR datasheet" isn't reason enough?

>>1410148
also, consider a hot-air gun of some sort. the $20 paint stripping guns on high heat are pretty good, just wave hot air over solder side of board in general area of component and gently pull/jiggle from component side until free. you can modulate temperature somewhat by modulating distance from the board

>>1410551
here's an interesting set of slides, concentrates mostly on the common-emitter and common-base topologies, but if you can't into big books this should give you most of the basic idea
https://www.utdallas.edu/~torlak/courses/ee3311/lectures/ch05updated.pdf

>>1410645
no, linear regulators have no facility for transforming voltage to current. they pass the same current but turn the extra voltage into heat, as if self-regulating resistors
step-down switching converters do supply more current than comes in, on average

>>1410657
>also, consider a hot-air gun of some sort. the $20 paint stripping guns on high heat are pretty good,

as someone who has tried this, i can tell you it's about 5% effective, and 95% horror-show of repugnant smells, smoke, and burnt fingers.

>>1410670
oh, I meant these
also work in a well-ventilated area

>>1410657
thanks, I'm into big books but the one I'm using is a piece of shit. (sedra's microelectronics)

Yay my component package from Ping Pong finally came, we electronic engineers nao

>>1408236
>Arrow
are they new?
back when i was still into diy elec, i only ever ordered from mouser, digikey and occasionally newark

ordered from arrow from the first time and got free standard overnight, even from an overseas warehouse

how the hell do they do it?

>>1410769
>free standard overnight, even from an overseas warehouse

how is that possible. I need to start using Arrow, if the prices are good too.

If a battery says on it 1.800mah does that mean that if i short it the wire will have 1.8A flowing in it?

>>1410776
No, it means if you draw 1.8A from it it'll last nominally 1 hour before it's empty.

When shorted you'll get quite a lot more than that.

>>1410757
got a magnet? Check the wires, see if you got chink'd with copper clad steel.

>>1410788
to add to this post, in case >>1410776 didn't know, batteries (especially lithium ones) also come with a max discharge current rating. If you short the battery i'm betting you'd probably go over that limit, damaging the battery.

>>1410793
What is the maximum current then? I don't want to burn my multimeter after is short the battery with it

>>1410776
>>1410788
Yes this, the "Ah rating" is the charge held by the cell. Multiplying the current you're draining from the cell by the time it will take to drain will (ignoring inefficiencies) give you the same value, 1.8. Or in reverse, t = Q/I, where Q is your charge rating, I is current in amps, and t is time in hours. You can multiply Q by the voltage of the cell, probably about 3.7V average, and get the energy capacity of the cell as measured in Wh. In the same way, you can see how many watts you can pump out for how long with the equation t = E/P, where E is your energy rating and P is power in watts.

Lithium batteries aren't terribly user-friendly though, you have to charge them with a safe current profile and only to a certain voltage, you can't discharge them too far or at too high a current, but thankfully they don't have the memory problems that NiCds have. I believe it is possible to rejuvenate an over discharged cell through careful current profiles, but it's not easy and not something you want to be doing often. I'd recommend buying some Li-ion charge protection circuit boards, they're a dime a dozen. You can also buy the USB-out 5V boost boards.

Oh though there are protected Li-ion cells, which I guess you could have bought, which contain voltage protection, though I'm unsure whether they contain current protection.

>>1410801
You will NOT find the maximum safe current rating by shorting the cell, that will surpass the maximum safe current rating. Look for a datasheet or info from the seller. A value measured in "C" (like 10C, 40C, etc.) is fine, multiply your charge/capacity in Ah by this value to find out how many amps you can safely draw.

>>1410801
yeah you have to look at the data sheet.
Look at this for example: https://hobbyking.com/en_us/turnigy-nano-tech-300mah-2s-35-70c-lipo-pack.html?___store=en_us..
It says "discharge: 35C". Now C rating is something else you might want to look up if you're interested (see the pdf link in the OP), but that basically tells you how much current you can safely draw from the battery before it overheats or worse, explodes. Note that it is merely a maximum value, the load will draw the current it needs, depending on its own resistance. (Just putting this out there because it's a common misconception even in these threads).

I am at a store and need quick advice. How many ohms do i need coonected to a 3v branch of a psu to simulate load and keep it on?

I am looking for resources on how to improve power efficiency in my circuit designs and perhaps lower current usage as well. Anyone willing to share tips, books or application notes?

I've built this circuit to control a couple of small solenoids on a 3-way point for a model railway. The SPDT works fine (the solenoids are wired in parallel), but when I close the DPDT in either direction, one solenoid throws immediately but the other struggles and generally won't throw (they're wired in series so I suspect this is the problem).

How can I fix this? I'm using a 16v 500mA transformer, would a more powerful supply overcome this?

>>1410817
I guess it's too late but it depends on the PSU no? Specs should tell you the minimum load current and from there you use ohm's law.

>>1410843
>they're wired in series so I suspect this is the problem
Sounds reasonable. What is their nominal supply voltage?

>>1410817
Trial and error I'm afraid, unless PSU topologies are less varied than I'm assuming. Those USB-powered variable loads with a fan and heatsink look pretty useful for this sort of occasion, though making one with a 555, big capacitor, MOSFET, and "power" resistor would be a pretty easy way to go about it.

>>1410848
And current too, please.

>>1410848
The voltage is between 14v and 20v. I've looked everywhere but I can't find anything definitive with regards to how much current they draw other than it's less than 1.5A each (probably closer to 500-750mA).

Ideally I want to use a 14v 5VA transformer (which is provided by the existing controller for the train set) but the transformer I'm testing it with is marked as 16V 8VA, so if it doesn't work with this one would I be right in thinking that it wouldn't work with that either?

>>1410850
Well i will just keep adding resistors until that fucker stops turning off all the time.

Also, the psu has several branches. There are for example the sata branches which have a power power that is like 5 volts. If i tie two of those wires together i will still get 5V but with a nice bonus of being to able to get twice the current before meltdown right?

if a component says it can handle 5A VAC does that also mean 5A DC?

What's the difference between solder with silver in it and solder without, and what difference does the amount of copper in it make?

>>1410872
>if a component says it can handle 5A VAC does that also mean 5A DC?

If you are talking about relay or switch contacts the answer is probably no, and if the device is not also rated in DC terms I'd avoid it.

what sort of device is rated for AC only that you plan to use with DC?

>>1410886
Whops it's actually 15A VAC.


It's a chink relay I got for my raspberry pi and I want to switch a heater with it which runs on 12V 10A DC

>>1410892
Forgot link
https://www.aliexpress.com/item/Free-shipping-5V-low-level-trigger-One-1-Channel-Relay-Module-interface-Board-Shield-For-PIC/32334324925.html?spm=a2g0s.9042311.0.0.5df34c4ddvSt0d

>>1410892
What is the difference, if any, between using a relay and a mosfet for this sort of thing? (Legit question, I'm a beginner myself).

>>1410907
It separates the control current from the load current. You can't use mosfet to turn on 230V AC from a RPI for example since RPI is 5V DC

>>1410910
because you'd risk the voltage drop between gate and ground to be higher than that between gate and RPi? Or am I completely off the mark?

>>1410915
>completely off the mark?

yes. it's because you'd have a galvanic connection between the 230Vac and the raspi, meaning your circuit could easily be live to the touch. thats a very bad thing. a relay creates an air gap between the low-voltage and high voltage sides, so your chances of electrocution decrease considerably.

In this video, the man wired a temp probe to the RPI.
Ground to ground, positive red to 3v, yellow data to a GPIO data pin. All perfectly normal... and then he adds a random resistor between the postiive and the data wire.. what the fuck?
Why???
https://youtu.be/76CD_waImoA?t=5m59s

>>1410958
The resistor between 5v and data is needed for 1-Wire communications as it's what pulls the data wire up to 5v to make a 1, the devices on either end only pull down to make a zero.

>>1410958

I admit I have no patience or attention span, so maybe that's a great video, but did it really take almost half an hour to talk about measuring water temperature? I bet you could put all the actual information on one page that you could read in two minutes.

>>1410965
Can you rephrase that?
Do you mean that the data wire needs to be powered to function so the resistor pumps 1 volt into it? But i don't understand how that helps anything, if you have constant 1V on it then how do you get any data?

>>1410970
logic 1, not 1v. It's not constant, either device pulls it down to 0v = logic zero when needed, or let it float up to 5v to make a logic 1.

>>1410973
How can the probe pull it down though? Does it like say short the data wire to the ground wire to create 0 and the remove the short to create 1? Wow that is pretty smart, I had no idea chinks were so good at this stuff.

>>1410977
That's exactly it. It's a common system for communications with multiple devices on a bus or bidirectional data on a single wire, both of which are used here, you can attach dozens of DS18B20 probes to the same shared 1-Wire data line (although you need to be a bit careful with cabling when you have lots)

>>1410981
If you put several probes on a single GPIO pin, how will the RPI know which probe is trying to talk with it?

>>1410983
Each one has a unique serial number/address.

>>1410986
Yeah, if the talk one at a time. But if they all try it at the same time then the signals get all mixed.
Unless the other probes have some mechanism to listen for other probes talking and keep silent if they detect that some other probe is running its mouth.

>>1410987
The RPi is the Master which is allowed to talk at any time, all other devices only talk when they're requested to by the RPi.

>>1410958
If you wanna use that probe, be aware those things have strict timing requirements, so you can only nigger rig it with any old wire for short lengths. I tried with longer, didn't work. The company's design documents say how to design 1-wire networks properly.

>>1410989
So it's like america during the 50s, got it.

>>1408236
I found these resistors on both the positive and the negative terminals of an rc car's motor. I've broken one apart to see how long the coil was. When I test them with my multimeter, they both show 0.04 ohms. How could that be? I can't even find resistors with so little resistance to purchase.
Also, what would be the result if I tried to run the rc car without these resistors?

>>1410997
Forgot picture.

>>1410998
They might be diodes to prevent voltage spikes going back into the rest of the circuitry.

>>1410997
They're inductors to supress high frequency interference coming from the brushes. Will likely work without them, but may have worse radio reception.

>>1410997
Its not a resistor, its an inductor.

>>1411004
>>1411003
Oh, that makes sense. Thanks guys.

>>1410993
I need a meter at most.

>>1411003
Wait, is it really used for that? How does that work and where can I learn about it?

>>1410852
Try wiring them in parallel?

>>1411019
Yeah that's what I've been trying to figure out. This looks like it'll work, I'm just trying to see if I can do it with fewer diodes now.

if I do this, is the second solenoid going to act like it's wired in parallel or in series?

>>1411009
That'll work just fine.

>>1410826
there is no one-size-fits-all prescription, other than "draw less current, less of the time". some practical suggestions:
1. don't use linear regulators
2. turn stuff off when you don't need it
3. avoid using prebuilt boards with crap you don't need on them
4. take note of pullup resistances, try to avoid making current flow through them most of the time
5. shop for components according to current consumption
6. use low-Rds(on) FETs instead of bipolar transistors

>>1410966
and this is why I hate vblogs

>>1410997
as they said, those are inductors. you can buy milli-ohm resistors quite easily off the shelf, but they'll cost somewhat more than the everyday metal-film devices

>>1411018
any theory book dealing with inductors. you might try Art of Electronics, 3rd Ed. despite the "advanced" heading, it's really only about intermediate

>>1411027
wait, are you powering this from ac or dc? might want to use the right symbols/sources in your simulator so that it makes sense. I see you've got a short across the power supply when top switch is up and bottom switch is up, for example
it seems like there are lots more diodes than are necessary, too. you might want to write up a truth table (expected outputs for each input) and see about simplifying it for comprehensibility. it's likely you only need diodes on one side of the solenoids and can tie the top side to the power supply for comprehensibility. of course, if you are using ac, diodes aren't going to do logic for you, use relays

>>1411033
>are you powering this from ac or dc
It's powered from AC, the transformer for the train set being used has an AC output for this kind of thing

>I see you've got a short across the power supply when top switch is up and bottom switch is up
yeah that's fine, it's not designed for both to be pressed at the same time, the idea is only to need to press one of the buttons to select a specific direction.

>if you are using ac, diodes aren't going to do logic for you
Well the diodes basically rectify the AC to DC and prevent short circuits. It works as I have it now, but because the solenoids are wired in series, the second one isn't receiving enough power to throw properly (but they both throw as expected when wired in parallel)

I had designed this for DC using relays previously (pic related) but as the controller provides AC, it's more convenient if I design it for that instead. Also apparently rectifying AC to half-wave DC means the solenoids are less likely to be damaged if the button is held down too long.

>>1411040
This schematic might be a bit clearer for the DC circuit above

>>1411033
>some practical suggestions:[...]
Thanks for the tips

>>1411126
no problemo. I should modify tip 1:
>don't use linear regulators where Vin-Vout is large, and shop carefully for them based on quiescent current
also
7. consider external components (opamps, regulators) with external shutdown inputs where it makes sense
and
8. be careful that circuits that are shut down aren't sucking current from their inputs or outputs

>>1411040
>works as I have it now
>except it doesn't work
and this is why you need to back up and consider redesign
>Also apparently rectifying AC to half-wave DC means the solenoids are less likely to be damaged if the button is held down too long.
possibly, I'll buy this for the sake of argument

>>1411043
one drawing is missing switch wiring, one isn't working, neither communicates the intent of your design well. nor have you been consistent about motors vs. solenoids. also, thanks to your ac supply, you have two circuits here, not one, making analysis all the more difficult
unless your switches are doing double-duty for some other control function, you should try to work this out so that you have exactly one diode right off the transformer that's doing the half-wave rectification (so it can be disregarded), and maybe one of the poles of switch(es) could be fed from one of the throws of the other. to do this I suggest you start with a function table
M1 is a ______, M2 is a _______ (solenoid, motor)
up/up = M1 _____, M2 _____ (motor fwd, rev, off) (solenoid on, off)
up/down = M1 _____, M2 _____
down/up = M1 _____, M2 _____

>>1410931
optocoupler

>>1411133
ok so >>1411043 works with DC power. I forgot the switches weren't on the PCB layout hence why I posted the diagram afterwards

>>1410843 conceptually "works" with AC power, but because the solenoids are wired in series off the DPDT, the second solenoid doesn't get enough power to throw. As far as I can tell >>1411027 should work fine with AC power, it's basically the same thing but with the solenoids wired in parallel from both switches.

>thanks to your ac supply, you have two circuits here, not one
no the reason for that is that I'm trying to design this such that you only need to press one of 3 switches to set system to either up/straight/down. There's a DPDT for up/down and a SPDT for straight ahead (all momentary). I'm making this for my nephew and I want it to be as easy to use as possible, i.e.: one button to represent each direction.

>maybe one of the poles of switch(es) could be fed from one of the throws of the other
that's what I'm trying to avoid, I don't want to have it set up so you have to press two buttons to set the direction.

Pic related is what it's to control, there are two solenoids, one for up/straight ahead, one for straight ahead/down. The truth table for this is:
10 10 (up)
10 01 (straight ahead)
01 01 (down)

The problem with using just one diode is that because the circuit needs to support reversing the polarity of the solenoids, they need to be isolated from each other. It might be possible to do it with relays using AC as well, but diodes are a tenth the price (although admittedly they don't make the cool clicking sound that relays do).

>>1411133
btw if you want to test this circuit out you can do it here:
http://falstad.com/circuit/circuitjs.html?cct=$+1+0.000005+10.20027730826997+50+5+43%0Av+-80+288+-80+176+0+1+40+5+0+0+0.5%0AS+32+48+160+48+0+0+false+1+3%0AS+32+112+160+112+0+0+false+1+3%0AS+32+384+144+384+0+1+false+2+2%0AS+32+448+144+448+0+1+false+2+2%0A181+528+96+528+208+0+300+100+120+0.4+0.4%0A181+528+240+528+352+0+300+100+120+0.4+0.4%0Aw+-80+176+-80+48+0%0Aw+-80+48+32+48+0%0Aw+32+112+32+288+0%0Aw+32+288+-80+288+0%0Aw+160+96+320+96+0%0Aw+320+96+320+208+0%0Aw+256+32+256+64+0%0Aw+256+64+448+64+0%0Aw+224+64+224+80+0%0Aw+224+80+320+80+0%0Aw+320+80+320+96+0%0Aw+160+128+256+128+0%0Aw+256+128+256+64+0%0Aw+144+432+208+432+0%0Aw+32+384+-16+384+0%0Aw+-16+384+-16+176+0%0Aw+-16+176+-80+176+0%0Aw+32+448+-80+448+0%0Aw+-80+448+-80+288+0%0Aw+144+368+608+368+0%0Aw+448+64+448+96+0%0Aw+448+96+448+240+0%0Aw+528+352+320+352+0%0Ad+320+352+320+208+1+0.805904783%0Aw+224+64+160+64+0%0Aw+256+32+160+32+0%0Aw+608+368+608+240+0%0Aw+528+96+640+96+0%0Ad+608+240+528+240+1+0.805904783%0Aw+608+208+608+240+0%0Ad+448+96+528+96+1+0.805904783%0Ad+448+240+528+240+1+0.805904783%0Ad+272+464+208+464+1+0.805904783%0Ad+272+432+208+432+1+0.805904783%0Aw+208+464+208+432+0%0Aw+528+208+320+208+0%0Aw+272+432+528+432+0%0Aw+528+432+528+352+0%0Aw+272+464+640+464+0%0Aw+640+464+640+96+0%0Aw+608+208+528+208+0%0A

>>1411158
any internet nerds can chime in and explain what the fuck is up with websites having these links? Aliexpress does the same

>>1411162
yes it's literally the schematic encoded into the link, each bit between %AO is a different component of the circuit including the wires, it means the website doesn't actually have to save anything on the server side.

idk about AliExpress, they're probably keeping a lot of tracking information and whatnot.

>>1411162
>being so new to the internet he hasn't heard of a query string
try /g/, they'll explain it all to you in mind-numbing detail

>>1411156
>There's a DPDT for up/down and a SPDT for straight ahead (all momentary)
what you have drawn is a DP3T OR a DPDT with center off (assuming this), and a DPDT without center-off. I'm assuming the drawing is correct?
>that's what I'm trying to avoid, I don't want to have it set up so you have to press two buttons to set the direction.
you wouldn't, if you have normally-closed contacts. it turns out we don't need them
>truth table
ok, I think I get it now. the ac source and half-wave rectification are now useful instead of a hindrance. how's this?

>>1411180
>DPDT with center off (assuming this), and a DPDT without center-off
They represent a DPDT with center off i.e.: (on)-off-(on) and a DPST momentary i.e. off-(on). Falstad doesn't allow you to or make center off switches or group momentary ones, so I had to draw a DP3T and a DPDT to achieve this.

>how's this?
It's pretty fucking good, I have to admit - it took me a while to wrap my head around it. I wrote out a whole response about how it was bad (from a UX perspective) and you should feel bad, then I realised that the second switch is supposed to be an on-(on) momentary and the first is (on)-off-(on) and now I feel bad.

I wish you had been here earlier to school me anon, I already ordered the diodes and I won't be able to get an on-(on) switch before monday now. I'm sort of inclined to proceed with my original plan just because I can get it done over the weekend even though yours is technically simpler.

>>1411217
if the straight switch is DPST, you could just wire the NC contacts of the second switch to the common. the only thing you lose is protection in case both switches are actuated at once

>>1411222
Huh. Do you do this for a living? You should probably do this for a living.

Thanks anon. I can't believe how simple this was and how complicated I managed to make it. Or that nobody else was able to think of this.

>>1411180
I don't really get what the circuit is trying to do anyways. In one arrangement you're switching between both solenoids being powered on the same half-cycle, and on the other you've got one on each half-cycle.

>>1411278
it's a control box for a 3-way model railroad switch. the motors are polarity sensitive, akin to single-coil latching relays. for this application, capacitors aren't required. see Pic related at >>1411156

>>1411226
thankee. not doing this for a living rn, but I did in my teen years, briefly. I should consider doing it again for my next career change
to be fair, it took a bit to get the half-wave configuration info and that truth table out of you, but that's a day in the consulting life

>>1410383
actually i do that shit all the time at work with nothing but desoldering braid, you're just bad

>>1411316
>at work

seems your employers dont understand that ''time is money'' or they would spend $50 to get you the proper tool to do a faster, cleaner, job and with a lowered risk of causing damage to the PCB. must be Juice.

>>1408236
How do we stop youtubers from teaching people to make death traps?
https://www.youtube.com/watch?v=gAbPoYRlQl8

>>1411308
Ah that makes sense. I just wasn't sure how to interpret the truth table. Though thinking about it now I wonder if you could simplify it by incorporating the do-not-care condition of the second junction when it's switched to go to the right.

Is 40Hz normal for your country or something?

>>1411385
Fuck, I wasn't gonna watch it but I thought it looked pretty neat from the image shown. The only problem I see is the slightly janky splice and ingress-prone inline switch. But why the hell is black live and white neutral?

In any case it's better than Homemade Modern's copper-pipe lamp with an ugly concrete traffic-cone base in which the electronics were left completely unexplained because "ask an electrician", leading to a few hundred "you should ground it" comments.

My relay is rated for 10A but i need to run 15A through it.
So i took two relays and connected them in parallel so that the current is split and each of them only has t deal with 7.5A.
But there is a possible problem. When the relay turns off it has to quash the fieary arc of DC death that manifests it self as the contacts start to distance themselves.
The problem is that the relays obviously won't close at the same time down to the nanosecond, so for like a millisecond or so the one relay could close killing the arc, but then for that milisecond the other relay's arc will be fed the additional 7.5A which will instantly weld it shut and force a painful, fiery death on me and my family during the night.

So how do i prevent this from happening?
>j-j-just like use SSR rated for 15A
NO. I do not have that kind of cash or time. I can only use what I have.

>>1411391
relay contact snubber

>>1411391
Idk, capacitors lol

>>1411392
>relay contact snubber
Can you show me how to make that with a circuit diagram?
The load will by drawing 12V 15A DC

>>1411391
>>j-j-just like use SSR rated for 15A
>I do not have that kind of cash or time.
putting in s-s-stutters don't make good advice wrong.
why are you nigger rigging this anyway, what's so important that you can't wait any longer?

>>1411397
Imagine having a 20m long wooden plank you bought for $20.

You have no use for it so it sits around, wasting space, doing nothing, good for nothing, just like a millennial.

But then you need to do a project. And lo and behold! You need a plank for it! Finally! But oh no, the plank you need needs to be 15m long and the one you have is 20m long.

So you go to the store and spend another $15 on a 15m long plank and finish your project.

And you are still $20 in the hole with a useless plank taking your space, when all you had to do was grab a saw and take 5 minutes to cut the 20m plank to 15m and all would be wonderful and ideal. Your project would be finished, and you would get your plank money well worth.

If you are rich then you might not care, but if you are poor then this makes a big difference to you plus it's good for morale knowing you haven't wasted your precious coins.

I find it strange that I have to explain this concept to you, it should be clear to anyone who has ever had to pay for staff with their own money.

>>1411399

ok, so I should saw the relay or what.

>>1411396
I figured out how to do it with inductors, by putting an inductor in series with each relay, the current through the relays will resist change. Since an inductor is defined as V = L*dI/dt, we can make the assumption that dI/dt is constant (not exponentially decreasing like in reality) to give ourself a good, if not too generous estimate of the system's behaviour. Since initially 7.5A will be going through each relay, we can imagine 6V will be dropped by the resistor from due to the current through each relay at t=0; at the time when the first relay has turned off. The current through the relay will start increasing at a rate this constant dI/dt for a time length ∆t (the duration between the first relay going and the second relay going), meaning the current increases by ∆I = ∆t*dI/dt. If you want to limit this to 10A then ∆I = 2.5A, so 2.5 = ∆t*dI/dt.
Since V = L*dI/dt, 6/L = dI/dt, 2.5 = ∆t*6/L.
Rearranging this we get L = 2.4∆t, with which you can build a circuit (not forgetting the diodes). You'd need to measure ∆t 20 or so times and go with an upper estimate, using a scope, arduino/mcu, or even sound card. If you'd end up with an inductance above 10mH or so (∆t > 4ms) you might be better off trying some other method, since 10mH is pretty tough to get cheaply/have lying about and chances are the ESR will be too high. You'll probably want an inductor ESR below 0.1Ω.

I can't think of any non-active way of doing this with capacitors, they'd just back-feed into the sole active relay and put even more current though it.

>>1411396
use an automotive relay you dipshit

>>1411399
>reddit spacing
>obligatory complaint about millennials being lazy
>wants to be spoonfed
>roundabout and irrelevant analogy
>writes like a neckbeard
you sound like an insufferable cunt la

>>1411435
>automotive relay
that will do absolutely nothing to prevent welding

>>1411440

If you could read angryfag's mind, he was saying that automotive relays are for 12 volts DC and it's easy to find one for 15 amps.

>>1411441
the problem is that the maximum control i can pump out is 5V and the car relays are usually made for 12v control.
And using step up circuits and such is really out of the question since i don't have them and at that point i could just shell for SSR
I am basically limited to what i have on hand

>>1411450
You should be actuating the relay with a transistor anyways.

>>1411451
You mean using a part of the triggered current to trigger the relay?
but that will lower my precious precious load voltage

>>1411455
No m8

I have an old-ish pc where the software only allows for automatic control of CPU fan, I think the CPU fan is PWM controlled so is there any issue with just splicing in another wire that goes to a fet gate, then connecting +12V to source and the fan to drain (or the other way around, cant remember polarities)

>>1411465
Some computers won't boot up properly if they detect a fan hasn't been installed properly, but it's fairly easy to spoof these detectors. For this reason I'd hook just use the existing PWM pin on the fan (if available), since the PWM pin would require the least current (if any) to spoof. If unavailable, you'd do well to look into what circuitry computer fans use to handle their speed controlling, and what frequency they PWM at, so you can replicate this with your own hardware such that the computer sees nothing wrong. Making the fan pull more/less current than intended might be a problem if the computer has a current shunt on the fan's 12V/GND pin, not sure how you'd go about spoofing a lower current.

I'm just going off what I learnt from a YT video so definitely look into this yourself however.

>>1411464

there should be a diode across the coils or the transistors will get a huge induced voltage at turn off.

>>1411464
but where do i get the 12v for the transistor? I only have 5v

>>1411470
Well there should have been in the original circuit too so I left them out. I definitely didn't forget about them.

>>1411466
I mean running another fan alongside the CPU fan, with CPU fan being connected in the normal manner and the other fan connected to a +12V fan header except with the FET in between, the CPU PWM would be controlling two fans but I can't see how that's an issue with FET's high impedance

>>1411479
Ah, yes it would certainly be possible provided the computer doesn't detect over-current. Just don't forget the snubber diode, else you might have a pretty expensive fault on your hands. The output impedance of the computer's PWM pin will easily handle an extra FET. Even if it does detect over-current you could just wire the second fan away from the current-shunt (I'm guessing it would be on the negative rail) directly to the PSU. Might want to add a fuse to it in that case though.

I know the op lists spice versions to use but are there any good tutorials/books to use to learn spice?

>>1411491

lol are you lost >>>/ck/

Is there a middle ground between aluminium and polypropylene in terms of audio capacitors? On the one hand I want good sound quality, but on the other hand 5 bucks per cap is simply not copacetic

>>1411494
Large part of that is just audiophile superstition.
Mylar/polyester is the most commonly used and also the cheapest dielectric for plastic capacitors. It is widely used in audio shit.

>>1411491
If you head on over to the LT website where they've got spice dl links you'll find a section with documentation, among which is "LTspice Information Flyer & Shortcuts" and "LTspice Getting Started Guide". I'd scan through the latter, but it isn't terribly comprehensive. But if you scroll to page 2 on this you'll see an older list of more documents, pic related, of which the "LTspice Users Guide" is I think what I searched for. I don't think it's the original one, but
>http://www.editorialdigitaltecdemonterrey.com/materialadicional/id212/cap1/LTSpiceGuide.pdf
is what I found and it's quite comprehensive, with AC analyses and such.

i've got a weird PIC16F54 problem. i'm trying to count a ~14kHz signal using the counter peripheral with a 32.768kHz system clock. the problem is that i don't get a count until about 135 delay ticks (see image).

i've stripped the asm down to the minimum, about 25 instructions. i've checked the circuit, the target signal is present on the T0CKI pin and is a pretty clean rail to rail 50% duty square wave. the code i've excluded that displays the value also works correctly as tested by giving it fixed values to display. does anyone have guesses as to what's causing this?

code: (https://pastebin.com/raw/2yL5whWb))
>clear TMR0
>loop for N cycles
>save TMR0
>display saved value on two 7segs

>>1411510
http://ww1.microchip.com/downloads/en/DeviceDoc/41213D.pdf

datasheet for those not familiar. it's a far dumber chip than most 12fs or 16fs.

anyone lives in a tiny apartment can give me tips on storing components? things are getting out of hand here and escalating quickly.

>>1411517
rent a garage

>>1411517
these in a banker's box. i also have a piece of shit akro-mils drawer from amazon that holds all my passives.

>>1411518
not possible on the third world, also broke EE student.
>>1411519
thanks

>>1411517

this is more of a QTDDTOT even if it is electronic components, but anyway, one thing you can do is put lots of things that aren't used frequently into one box. either label the box if that works, or assign a number to the box and have a list somewhere, either on paper or in a computer file, that says that "BDCM motors are in box 14".

the other thing is to decide what warrants its own container, and what does not. I have about 10 resistor values from 68 ohms to 10 meg that are in little drawers so they are easy to grab. All my other 1000 resistor values are in baggies, with all the "yellow stripes" in one, "red stripes" in another, and so on, so there's about 10 baggies that make it easy to find the ones that are multiples of whatever.

Same thing with pic related. Deciding what goes in here, what deserves its own tray, and what gets put in box 14 is the hard decision, and you might need to fine tune your scheme for the rest of your life, small apartment or huge workshop.

>>1411510
Firstly, PIC assembly is ugly and I hate you.

> BSF PORTA,003H ;Toggle mux to direct frequency being measured to T0CKI

Is this a mux outside of the micro?

> i'm trying to count a ~14kHz signal using the counter peripheral with a 32.768kHz system clock

Is the 32.768k the main oscillator? If so, that isn't going to work, the input is only sampled on every second oscillator clock tick, so the fastest input frequency you can count is slightly below quarter of the oscillator clock.

Anyone has comments on chink multimeters like this?
https://aliexpress.com/item/WHDZ-DT9205A-Professional-Digital-Multimeter-Electric-Handheld-Ammeter-Voltmeter-Resistance-Capacitance-hFE-Tester-AC-DC-LCD/32797460240..

>>1411523
good catch, i had misread the datasheet as saying the maximum frequency was fosc/2 not fosc/4. anyway i set the prescaler to 1/2 to get around this and found the same issue. delay counter values below 135 don't just overflow, they actually all read zero.

>>1411524
>forgetting the .html
https://aliexpress.com/item/diy/32797460240.html
That's how to make an ali link. I'd personally get an Aneng AN8008 instead, it's true RMS, auto-ranging, 9999 count, though a little more expensive. It's a well-known model also, you'll find plenty of reviews about the place.

>>1411530
well i solved the problem by adding a 135 cycle delay before clearing the register and doing the actual count. then i got this result. that's when i realized BSF should've been BCF and i was targeting the wrong sensor.

>>1411522
This anon gets it. Get a label maker and label every box. You may have only a few spare components at the beginning, but as time goes on knowing exactly where things are and where to put them will be a real time saver.

>>1411388
>But why the hell is black live and white neutral?
In the US, white is always neutral, and black is one of the colors for hot.

>>1411633
have you ever seen a black fire? Or black hot piece of metal?
Red is hot son.

>>1411634
I didn't write the electrical code, I don't think that black is a good color for hot either, but that doesn't change what it is.

>>1411634
>>1411637

american wiring has two hots, red and black, white neutral, and green or bare copper ground.

black vs. white was a tossup and they chose black.

>>1411638
Actually, blue is also a color for hot, in three phase cables.

Theres a 40-50VAC line around 50-100kHz i need to feed it into an MCU to monitor the frequency.
I came up with this thing that should isolate and drop the voltage so the MCU wont pop. Right now it works with a 4.7uF electrolytic but thats just what i found. What is the optimum capacitance for a circuit like this? Which side should the negative lead of the cap go?

Not sure if i should limit the current through the zener.

>>1411643
Correction. Its actually a ground referenced squarish wave.

>>1411180
>try /g/
Worst place to send people to learn.

>>1411644
if it's ground referenced, as in the mcu ground and not earth, you should just use a resistor divider and zener.

How does a diode protect against voltage spikes? It seems to me like it can do it only once because then it gets burned out and shorted forever

>>1411654
If the diode is fast enough it would open fast and drain the sexces voltage so it wouldnt build up to be an actual spike.

Also a voltage spike doesnt have much power, so it cant burn out a diode. Repeated spikes might carry more power to heat things up but heat will be conducted away from the junction.

>>1411654
most voltage spikes are small static or magnetic discharges with a finite energy so even if the current is briefly very high the diode won't heat enough to fail. some spikes, such as lightning, also count on series inductance and resistance to limit the current so the diode doesn't heat too much over the transient duration.

>>1411522
>$800
jesus fuck, I'll stick with banker's boxes

>>1411517
I use 1L zipper freezer bags for most of my ICs/transistors, in distributor packaging or its own zipper bag
for THT resistors/caps I use smaller zipper bags stacked up in ~8x12x10cm cardboard shipping boxes
for SMT on cut tape, I splurged on some empty sample books with empty pages each having 12 slots for cut tape
for DIP ICs I bought a large sheet of stiff anti-static foam years ago and cut a piece to fit a motherboard box

I want to wire up a 240v receptacle on a 50amp breaker for a welder. What are some good books/YouTube channels to learn how to do this properly? Just looking for good information on residential wiring.

Currently reading Wiring a House - Rex Caudwell.

>>1411641
>three phase cables
I have 3~400V and blue is N.

>>1411693

brown is too close to black, considering the color spectrum. what's wrong with you.

>>1411648
How about the capacitance? Which way should i turn the cap?

>>1411641
>>1411705
not sure about the rest of the world, but for example in european code blue is neutral and brown is live

>>1411709
I am starting to get the feeling that EU and US wiring codes are very, very different from each other.

>>1408236
What program do you guys use to make professional wiring diagrams?
There has to be a better alternative to AutoCAD

>>1411726

https://thepiratebay-org.prox.space/torrent/17290775/Altium_Designer_17.0.10_Build_617.iso

also

https://en.wikipedia.org/wiki/Comparison_of_EDA_software

>>1411726
KiCad is pretty good

>decided to dive in and buy Practical Electronics for Inventors Fourth Edition
>it gets here
>kinda heavy
>open up the package
>massive fucking book
The fuck did I just get myself into?

>>1411764
but anon it's free online

>>1411767
I like physical formats.

>>1411764
I hope you know how to find Fourier transforms and solve third-order linear, time-invariant differential equations.

>>1411774
No idea, I was hoping this would work for me as a somewhat starter. I know electronics, but I don't remember any of the actual math behind it.

>>1411778
I'm kidding. Just tape LEDs to batteries like the rest of us.

>>1411794

We bump limited already? These threads go down like a sack of bricks.

>>1411815

says right there on the right corner.

>>1411861
Oh I know, I was just expressing surprise in the form of a rhetorical question.

>>1411889

shoulda used an Interrobang then.

>>1411391
Wait a fucking minute, i don't need to switch the DC, i can just switchsafely the AC BEFORE it gets converted into DC
Thanks for not suggesting this obvious solution and letting me waste the entire weekend

>>1411962
You barely gave any information on what the deathtrap you're trying to build is. At least you learned to help yourself. You're welcome.

how many wats of heat can those small resistors handle in nonstop running?

Why is my multimeter reading 0 volts between contacts 1 and 4 on an usb power bank? I know the power bank works and is charged

>>1412003
shit, turns out that metal rectangle around it is grounded for some stupid reason and i have been touching it with the probe

>>1411984
Supply more than 1/2W if you want to use it as a LED instead.

>>1412006
It's grounded for shielding.

>>1411774
>third-order

Are these yellow things Tantalum capacitors?

>>1411705
No it isn't you dumb colorblind huehue.

>>1412085
Ceramic.

If capacitator is charged to some amount of farads, lets say it's rated for 100F 20V and i charge it with 10V so i get 50F, how do i calculate how long can this 50F power a device like a led that needs 3V & 20ma?

>>1412141
Ideal capacitor energy is 1/2CV^2 and your device consumes 3V*20mA=60mW, the led requires atleast 3V so we'll set that as our energy zero giving us 1/2(100*10^2-100*3^2) = 4550 Joules, energy/power = time so 4550J/60mW = 75833 seconds or 21 hours. The capacitance value of an (ideal) capacitor doesn't change with voltage so it's always 100F, 20V is just the rated maximum safe voltage before the voltage strikes through the plates.

>>1412141
Farads is a measure of charge per voltage, not of charge or energy itself. Stored charge = voltage * capacitance, so 10V * 100F = 1000 coulombs (amp*seconds). Stored energy = 1/2 * voltage^2 * capacitance, = 5000J.

Due to the voltage^2 part of the energy, if you get a 20V rated cap and only put 10V in, you're only getting quarter of the energy storage that it's capable of.

The big difficulty of using a supercapacitor effectively is you need a load that can handle a widely varying input voltage, to use a cap like that effectively you'd want something that can be efficient all the way from 20V down to ~2-5V before it shuts down.

For a load that small you'd usually be better off with a battery instead of a supercapacitor.

My power adapter can have positive and negative switched both ways.


This is a breadboard power supply, on bottom left you see the hole for the adapter plug, there is a metal stick in the middle, is the stick positive or negative?

>>1412170
fuck i tried some basics like connecting a led and those fuckers are sensitive as fuck, they are rated for 2V and i put them into 3.2V thinking that 1.2V ain't shit really and they fucking blew out INSTANTLY not even any smoke

>>1412194
lel, did you even put a resistor in series or did you really just want to kill LEDs?

>>1412198
i was curious to see how much it can take. Since i got like 100 of them for half a dollar i'ts fine frying a few

I calculated 160 ohms but only have 150, and it didnt melt so far so looks like 10ohms ain't shit.

If i want the led at half brightness will changing the resistor to 2*160ohms achieve that?

>>1412205
fuuuck why do they make those fuckers so tiny, i am having serious problems manipulating with them with my sausage fingers

>>1412218
what the fuck? I have LEDS in 4 colors and if i put 2 of the same color in parallel then they dim by 50% as they should but if i try to combine 2 different colors then one of them remains at full brightness and the other one does't turn on at all. I tried different color combinations and it is always the same 2 same colors = work, 2 different colors = only one lights up
This is some crazy shit man, i will probably end up regretting getting into this shit as a hobby soon

How are addresses numbered on chips?
I have an AT28C64 EEPROM, and it has addresses A0-A11. I had assumed that A0 was the least significant bit, but nowhere in the datasheet (at least as far as I can see) does it mention if this is the case.

>>1412259
I am breadboarding a programmer for the EEPROM and this makes it even more confusing as the shift registers I am using for the address and I/O bits have to be wired up in reverse as I am shifting in the LSB first (so shift register output QA will be the MSB and output QH will be the LSB). I think this would mean that I would connect QH to I/O 0

>>1412263
>>1412259
For context this is all being done for a multiplexed display

>>1412230
Different colour LEDs have different forward voltage, so if you put them in parallel the lower voltage colour (generally ones toward red) will pull most of the current, not allowing the higher voltage LEDs to get enough to light up. To solve this, use a separate resistor for each colour.

>>1412259
Conventionally A0 / D0 are the least significant bit, but on simple ROM/SRAM chips like this all the address/data have the same function, you can rearrange them in any way you want and it'll work fine, there is no inherent most/least significant pin on the chip. Just have to make sure if you arrange the pins/bits in some other way you'll also have to rearrange either your programmer hardware or the data file in the same way. It's pretty common especially for RAM to fiddle with the order to simplify PCB layout.

>>1412270
That makes sense. Thanks.

>>1412205
>If i want the led at half brightness will changing the resistor to 2*160ohms achieve that?

only takes 2 seconds to try it and see, you cunt.

>>1412309
Wow, so edgy, don't cut yourself.

What are these two different parts called? The left component has a 'T' on top of the box.

>>1412322
right is an inductor

What is the L351 part called? It looks like a resistor but is fat and doesn't have a inverse bulge in the middle like they normally do.

Also the big resistor above it with the sharp edges, is that just a high power resistor as opposed to those small ones?

>>1412326
"L" signifies an inductor. and yes.

>>1412328
Is there a full explaination of that printed code online?

>>1412330
"351" is an arbitrary number that is referenced in the device's service manual to get the part number or value. you can just read the color bands though.

>>1412332
No I mean the first letter code signifying the type of component. I'd be interested in having a list to refer to.

>>1412335
https://en.wikipedia.org/wiki/Reference_designator

>>1412336
Thank you.

>>1412322
The ones with T look like ceramic heater resistors, measure the resistance, it should be tens of ohms or less.

I have a 14x8mm screen pulled from a device that displayed a video slideshow of pictures and video from a SD card. Is it possible to repurpose the screen to use it as a small monitor? Perhaps to connect to my phone? I have a micro USB to HDMI port to connect the phone to the tv. If I connected a HDMI port to this little screen, would it work?

It's a shame to throw it out otherwise.

If i want to make a simple electro magnet by wrapping some wire around the coil, what will make the magnet reasonably stronger faster, adding wire loops or volts?
Like is it worth it doubling the amount of loops on a 5V el. magnet or would i be much better of using 6V?

the sum of tensions of Gate, source and drain must be zero ? Not vds,vgs and vgd; but vg,vs and vd

>>1412374
you need the controller the screen was using. Or to make one yourself

>>1412374

throw it out. you can get a monitor that size for like $5 at the thrift store. trying to DIY this will cost 10x that much.

>>1412377
>adding wire loops or volts?

the strength of the field is goes up with more current or more turns. but if you add more turns, that increases the resistance so you need to increase the voltage to make up for the loss in current.

>>1412383

you're confusing FETs with something else. your question is absurd. there's so such thing as SUM of tensions (voltages) on the pins.

>>1412389
>you can get a monitor that size for like $5 at the thrift store
Where are all these 6" monitors with digital inputs coming from?

>>1412418
china

>>1412424
Ebin af m8 lol eks dee xD

>>1411815
we get a lot of sparkies and shitposts lately, which "helps"

>>1412424

>>1412374
The parts you'd need to build to make it work would cost as much as a standalone monitor.

>>1412418
newark sells screen kits for just this sort of thing.

How fucked is this?

>>1412568
>burnt connectors
depends on what that pin connector connected to, and in turn whether there could be some other fault on the board elsewhere, either causing or caused by that fault at the connector. get history
>hair on the board
oh
scrap it

>>1412170
Stick is positive, almost always. Trace the PCB if you really want.

>>1412389
>you need to increase the voltage to make up for the loss in current
This is true, but usually you choose your wire gauge and number of turns for the voltage and magnetic field strength you want, since the magnetic field B is proportional to I*N. Through V=IR, you get V=k*R*B/N where k is a proportionality constant, which helps, but you should go all the way and calculate the length, and width of the solenoid in terms of wire thickness order to cancel more stuff out and get your final equation in terms of variables you care about.

So if inductor supplies current and capacitator supplies voltage, then what is the difference? They will both keep the circuit on for a bit after the power is cut

>>1412682
A capacitor resists change in voltage, so after turning the voltage across it off, it will continue to power the load that the voltage was powering for a little bit.
An inductor resists change in current, so after turning the current through it off, it will continue to power the load that the current was powering for a little bit.

Formally, a capacitor is defined as:
I = C*dV/dt
And an inductor is defined as:
V = L*dI/dt

If the voltage across a capacitor is constant, then dV/dt (change in voltage over change in time) will equal 0, so no current will flow. If the current through an inductor is constant, then dI/dt will equal 0, so there won't be a voltage across it.

Capacitors are typically used for power supply smoothing instead of inductors because they have much lower equivalent series resistance than an inductor holding the same amount of energy, and they stabilise the voltage, not the current. Moreso, if you had a flashing light that draws 1mA when off and 20mA when on, a capacitor across the input would provide whatever current the load wanted to pull, provided the capacitor is charged enough. But if you used an inductor instead, as soon as the current jumped from 1 to 20, it would take some time for the current to ramp-up through the inductor as it resists a change in current, leading to a lower voltage across the load. Even worse, when it drops from 20 to 1, the current through the inductor will remain at 20mA and slowly drop regardless of the voltage it's putting across the load, meaning this voltage could easily jump to 10 times that of the intended supply voltage and destroy your flashing light circuit.

This feature is used in boost converters, where current is passed through an inductor and then this current is suddenly shut off, and the rising voltage is fed into an output capacitor, and with some clever regulation this can be used to turn 5V into 12V.

>>1412688
In AC circuits, capacitors and inductors have a version of resistance known as reactance. Inductive reactance is proportional to frequency, while capacitive reactance is inversely proportional to frequency. If you have two sinusoidal signals, say a 50Hz one and a 10kHz one, you can construct a voltage divider with inductors and capacitors and resistors to attenuate the low-frequency component and allow most of the high-frequency component to pass. This is called a filter. For the previously mentioned "equivalent series resistance" reason, capacitors are used in filters much more often than inductors, which are a long length of thin wire and so often have many hundreds of ohms of resistance.

If you input "V = sin(2πf*t)" to "I = C*dV/dt" you will get "I = C*2πf*cos(2πf*t)", and since a cosine lags a sine by 90° or π/2 radians, the current through a capacitor will be 90° out of phase with its voltage. Similarly, this can be done with the equation for an inductor to get "I = -cos(2πf*t)/(2πf*L)", noting the negative we can see that the current through an inductor leads the voltage by 90°. The consequence of this is that the reactance of capacitors and inductors are rotated by 90° compared to ordinary resistors, so if added like vectors (head to tail) you'll have to solve for a right-angle triangle to find the total effective resistance, or impedance. Since inductors and capacitors have opposite phase changes, their reactance actually subtracts from one another.

We can extend this idea of phase differences into the complex plane, or Argand plane as it's sometimes known. Here a 90° phase change can easily be performed by multiplying or dividing by the imaginary unit number "i" where "i = √-1". Furthermore, as all frequency dependant components in a passive circuit are imaginary, we formalise it such that "2πf*i = s", and express all frequency dependant behaviour of a circuit in terms of s.

If i have power source that outputs DC 230V at 50HZ and has maximum load of 400W... is that maximum of 1.7A? Because that feels too small

>>1412699
Yes.

>>1412709
But then what is the HZ for since i calculated it only by using 400 = 230I

>>1412699

it's the law, mister. Homo's Law.

>>1412710
Frequency has no bearing on power draw.

>>1412717
then why does it even exist?

>>1412738
are you asking why frequency exists?

What's the point of this connector, and what is it called? Why use this instead of something you can disconnect, especially when you have 8 connections in the same one? Easier to assemble while saving a penny or two per connector?

>>1412738
AC is used instead of DC for a few reasons. Firstly, a transformer doesn't work via DC due to Lenz's/Faraday's law, and in the days before switching PSUs, transformers were by far the best way to change from one voltage to another. Transformers are still used for high-power and high voltage devices instead of switching PSUs, anything as or more powerful than a microwave and anything going past 500V or so essentially can't be done efficiently with transistors. High-voltage is important because it makes transmission lines far less lossy. If a power line has 1Ω resistance, then to transmit the same amount of power with 10V compared to 100V, you'd be loosing 100 times the power from resistive losses in a transmission line of the same gauge wire. Wire is expensive, and pylons can only support so much weight between them.

>>1412745
To stop it snapping off where the now soldered-solid wires meet the PCB? I know I always have that issue when I run off-PCB pots and switches to my PCBs, though I perhaps should be using coarser wire.

>>1412746
>To stop it snapping off where the now soldered-solid wires meet the PCB
Right, that makes sense. But I don't understand why they didn't go with something you can disconnect easily. It can't be more than a few pennies extra per connection, and it's two fucking two-wire connectors.
It's for the speaker connections on the amp/io pcb on a mass-produced but not cheap portable radio.

>>1412752
A penny saved is a penny earned.

Using a removable connector also adds the risk that it could come out when you don't want it to, especially in an environment where you've got vibration/shock, so portable radio isn't ideal.

>>1412767
They have used those in other places, so that was hardly a concern. And a penny saved is not necessarily a penny saved if you complicate the process of warranty repairs.

>>1412752
The ferrules might be removable from the plastic housing, though I doubt it. I wouldn't be afraid to cut the wires and splice in something detachable, even a Wago or two if you've the room.

>>1412259
Newbie question, why are you using a zif socket for jumper wires?

>>1413039
It's not a newbie question, I've no idea either. Perhaps it matches the pinout of an IC he's going to put in there later?

>>1413084
>>1413039
He's correct. I haven't programmed the EEPROM that will eventually go there so the jumpers are there for testing.

New idea:
Earbuds with IR LEDs and photodiodes in each end such that if both ends are pulled out it automatically pauses your music through momentarily shorting the sleeve to the second ring (TRRS).

>50 watt cob led chip
>60 wat sodlering iron
>apply flux
>try to solder wire into terminals
>solder never melts
>I can`t solder this fucking shit
pls kill me

so checking in, I tried to read through the theory portion of "Practical Electronics for Inventors". And I have to say, it seems a little complex for what would be considered intermediate it seems. Out of the starter books that are suggested here, what would you say is the best for someone who knows electronics but doesn't know the equations and theory behind it. Without getting overly complex like the one I have does?

>>1412265
>soldering wires to pin headers for breadboard use
mai niga

>>1413127
if you want your technique doctored, you have to show us
if the terminals are on a metal-core pc board you may want to consider adding a bit of preheat (100°C or so) with a hot plate or a hot air tool

>>1413127
Turn your clothing iron upside down on the lowest setting and place the COB on that to heat up. Those aluminium-backed PCBs are pretty good at heat-sinking, for better or for worse.

>>1413131
>who knows electronics but doesn't know the equations
I'd say knowing the equations, at least V=IR and P=IV, along with concepts of impedance operators, voltage and current sources, and maybe some general understanding of transistors or opamps should be considered basic knowledge. I think "Forrest Mims III, Getting Started in Electronics" is the one to go for, if you look a few threads back in the archives you'll find a Mega link full of them if you want to try before you buy (or never buy at all). The basic equations are high-school physics stuff, so you can forgive someone for assuming that you would already know it. Not that high school physics teaches anything more practical than ohm's law.

>>1413134
>high school physics
Well high school was 14 years ago, And the last time I learned these equations was 6 years ago during my AT training with the Navy.(which pretty much crammed everything into a 4 week course). I never used any of it during my career so I'm having to relearn it all.

But I'll look through the archives, appreciate it.