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/ohm/ Electronics General

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who generally electronics here?

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

>Links to get started
http://pastebin.com/9UgLjyND

also, general electronics thread
>>
>>900738

How much voltage do I need to drive this power mosfet

https://www.adafruit.com/products/355

Honestly the datasheet makes no goddamn sense to me.
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>>900776

Any advice on how to drive it with 3.5v
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How do I test the MaH of batteries?

I have some 3.7v 14500 2300mah batteries and a torch for them.

I suspect the torch may be 7w so if I record how long it takes the batteries to discharge through that torch what would the math be?

Pic related is the spec sheet of the torch.
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>>900769
> Honestly the datasheet makes no goddamn sense to me.
Soo.. You've not googled any of the terms in pic related to see what they refer to? Remind me again why we should do that for you..?
>>
>>900806

> "it's so obvious"
> proceeds to post the wrong data
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>>900835
> shitposting loudly
>>
>>900792
2300mah is 2.3ah
2.3 amps for an hour
7w at 3.7v is ~1.9amps
so ~1.2 hours
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>>900842
>>
>>900780
>http://pastebin.com/9UgLjyND
buy another one
>>
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I accidentally the 12 volt battery
>>
>>900842
>>900884
To be fair, it isn't immediately obvious what is the worst case Rds(on) at 3.5V gate voltage.
A simple answer would be that it's not a correct fet for 3.5V gate drive, though, and thus >>901026
applies.
>>
Could some EE guys help me on this?

I have some LiPo batteries that are fully charged at 12.6V, and I want to discharge them slowly to 11.5V. How can I achieve this?
I was thinking of using an Arduino to measure the voltage and use a simple transistor to switch the power off if the desired voltage has been reached.
I'm not quite sure if this will work at such a high voltage though, I think the arduino is only capable of giving 5V out.
>>
>>901097

you dont use an arduino to do a comparator's job. this page has some calculations on how to wire an LM339 single-supply rail comparator with hysteresis. you probably wanna divide the battery voltage by 3 using a voltage divider, and compare that against a reference of 3.83V (11.5V/3). for the hysteresis, around 0.2V or less should be adequate. use the comparator output to open a relay or deactivate a transistor when the voltage drops below 11.5V.

see section called ''The Schmitt Trigger''
http://www.learnabout-electronics.org/Amplifiers/amplifiers62.php
>>
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Electricity and pneumatics, a match made in heaven. Also it might deglove my cock, which is always fun.

Has anyone built something similar to this? The objective is to create a large, biased pressure oscillation in the latex bladder, which I estimate has a nominal volume of 12 cubic inches. The manifold is sized for 1/4" BSP thread. Also, the choice of relief valve is based on the usual rated pressure for soccer balls, which always seemed reasonably solid to me.

Apart from these, I have no numbers on the pneumatic side. However, I aim to achieve a maximum frequency of at least 120CPM in normal operation. I'm using the Photon because I had several units left over from school, and IoT development still sounds kind of fun despite the rapidly deflating hype.

>no sex toys
I promise I'll only post pictures of the machinery side.
>>
>>900867
Thank you.
>>
Ok /ohm/, I need your brains.
I live in Alaska, and its fucking cold. Last week it was 20f, now its -20f. -40 or even -50 are not unheard of during winter. The place I work at has outlets to plug your car in to heat the coolant, oil, etc. Great right? Well, because LOL MUH GREEN ENERGY GOTTA BE EFFICIENT they cycle on and off. Exactly how long on and off I don't know, but apparently it's not long enough because but every single time ive gone outside after a few hours after I plugged it in its always off (end of the plug has a light in it so it's easy to tell) and my fluids are always super fucking cold, and I know because I tested it at my house and the coolant was at 105 and oil at 75 when it was 0 out. This also happens to everyone else so its not just me.

Anyway, what I need is a device that every 5 minutes or so will break the circuit for like a second and the reconnect to reset the timer. I know this will work because if you disconnect and reconnect the plug it will immediately turn back on. It would need to handle at least 6 amps @120 volts (total of heaters is 700 watts) and preferably be powered by the plug, however being powered by the car battery is fine provided it only works when its plugged in. How would I go about making something like this? Or even better what can I buy that does this? Pls halp /ohm/ its really fucking cold and its only gonna get worse!
>>
>>901259
555 astable circuit connected to a relay that can handle 120vAC should do it. The timing is controlled by the capacitor and two resistors on the left. Use this to pick some values that make it on for five minutes and off for a few seconds: http://www.ohmslawcalculator.com/555-astable-calculator
>>
>>901267

The problem with that is it needs it's own power
>>
>>901259
why don't you just go out to your car 15 minutes before you leave and reconnect it so it will be thawed by the time you need it.
you don't need it heated fucking 24/7 if the engine isn't running.
no wonder they are on timers!!!
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>>901267
Thanks, kinda busy right now but I'll be sure to check it out later

>>901269
Like I said hooking it to the battery is fine and I'm sure I can whip up something to make it not on all the time

>>901273
Blow me. If the car is barely warmer plugged in than what it would be unplugged then what's the fucking point in the first place? Also I'm pretty sure youve never experienced -50 so double blow me.
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>>901274
>barely warmer plugged in
because you plug it in, it heats up for like 30 minutes say and then cools down for however many hours until you go back.
if you figured out how long it stays on for (ask someone?) then you could turn it on so its been running 100% when you are ready to leave so it will be warm.

>-50
>Fahrenheit
not a clue m8
>>
>>901277
Exactly, if it warms up for 30 minutes then shuts off for hours (when it takes 20 minutes or less to cool down from op temp of 200 for coolant and 180 for oil so the temp my heaters get it to will chill even faster then why even bother? Its fucking retarded. This is why I want to make this thing work.
Apparently it varies depending on temp, which may or may not be true (for example at +20 its on for 15 minutes off for 45, 0 its on for 30 off for 30, -20 on for 45 off for 15) so idk how long I could time it for. Even so I shouldnt have to stop what I'm doing just to go outside and re plug my car especially if I'm busy and don't know what time I'm going home.
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>>901280
What device are you using?
And good luck with the cold. It's already killing my body and we haven't even reached freezing yet. Fug
>>
>>900867
Kek, they lasted like 16 minutes.
>>
Hey /ohm/

I'm absolutely stupified by this circuit. It seems to not want to work whatever I do.

Its supposed to be a simple lamp dimmer, using a microcontroller. I've built the circuit from an application note in the MOC-3023 datasheet so I don't think that's the problem here. The damn this just wont work whatever I do...

I'm desperate now...
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>>901357
The application note from the MOC-3023 data sheet here:

http://www.ti.com/lit/ds/symlink/moc3020.pdf
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>>901358
Your mains is 220-240v, right?
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>>901359
Yep, 240 vAC at 50Hz

Also, Here is the part of the schematic I made that is relevant.
>>
>>900738
/ohm/ i want to replace the mosfet on my motorcycle. Its going bad. But there arent any new oem ones for it. Only used that will last who knows how much longer. Or really expensive new ones.. But from everything I can tell. They are just regular mosfets that sit inside a big heat sink. Covered in some sort of epoxy.

Anyone done this before? Have an idea where I should start? Also a new one is 240ish dollars shipped. So if I could DIY one for less then that im willing.
>>
>>901357

looks like your triac is wired wrong. the 180-ohm resistor and load go to MT2, which is pin 2 on the BT139. it appears you have it on pin 1. hopefully, you didnt put 120V into the gate which might blow the triac.
>>
>>901389
I thought it didn't matter which terminal of the triac you use, since it fires in both directions, am i wrong in that assumption? Anyway, I just tried as you said (Connecting resistor and load on pin 2) and still nothing happened.

In the circuit in my picture, I did connect it to 220v and it didn't blow the triac. It did absolutely nothing. Also, the gate for the BT-139 is on pin 3, not pin 1 as stated in the datasheet:

http://www.nxp.com/documents/data_sheet/BT139_SERIES.pdf
>>
>>901389
>>901392

Ok scratch that.. You were right. It was wired wrong. connecting the load and resistor to pin 2 worked. Changing the input pulse to the triac, actually changed the intensity of the bulb.

After about 10 seconds of operation the 60watt bulb promptly blew up! But atleast it ran! I'll try and figure out why that happened, but I have a feeling my input pulse might be the culprit. Again thanks, I owe you!
>>
I need a suggestion:
I am making a system where there is a Raspberry Pi acting as a master doing image processing, running computer vision algorithms and taking decisions and an Arduino acting sort of like a slave where it controls motors, speed and positioning of the system to realize the decisions and "goals" that the RPi established via its computations. My question is: what would be a more proper communication protocol to implement between the two: UART or I2C? I figure UART would be more efficient since the RPi is constantly checking if the decisions are met or, if the goal changes, change the setpoints and send it to the Arduino so it can pilot the system adequately, and these two processes are asynchronous(changes can happen at any time and the computing units aren't exactly mutually dependent). What do you guys think?
>>
>>901865
I2C is a strict master-slave protocol, the slave device can't initiate communications on its own. If that matters, use a UART, or add an extra alert line. In either case, make sure your protocol can handle missing or corrupted data. Also think about how the system can fail safely.
>>
>>900738
How would I design a circuit that allows me to take an input signal and add a tunable DC offset to it?
I thought I could make a summing amplifier, feed it negative voltage and at the output hook up a potentiometer to tune the voltage allowed through up and down.
I built it, but it's not working at all correctly.
>>
>>901875
You are right. Also, another thing that came to mind is that functionality of the subsytems themselves must be interrupt-based. If the Pi decides to change the setpoint, I want the arduino to control the system to the new setpoint, and not get stuck trying to stabilize to the previous setpoint. UART would be useful if the arduino detects some sort of failure in the system, it can report it to the master Pi. But can UART also support this interrupt-based system control?
>>
Pardon the dumb question, but I have one of these little siren speakers that are supposed to run off 12V. I'd like to us a microcontroller to produce a tone. What else do I need for that, an amplifier? If so, what kind?
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>>901914
> an amplifier?
Yes.
> If so, what kind?
One that matches the impedance (in ohms) and power rating (in watts) of the horn. Both of these details should be on the label on the rear of the horn. A google search for "xx watt amplifier for horn speaker schematic" should give you plenty of options. See what you can find and ht us with more questions of you need, but there won't be much to it.
>>
>>901914
are you sure its a speaker and not just a siren?
if its just some tones and you fancy building an amplifier you can just throw a basic transistor amp together or maybe an opamp if you want to get fancy.
>>
>>901897
I'm not too sure what you think the problem is, but AVR's UART receive/transmit can be implemented as interrupt-driven and things like decoding the commands received via UART (consisting of several characters) can be done using a state machine or whatever, so that your control and reception can run simultaneously and when a complete command has received, you just pass the decoded new set value to the controller.

>>901893
If your summing amplifier does not work, I'd check the power supplies and opamp's input voltage ranges first.
If your signal is AC, you could just use a resistor and a capacitor. Select a suitable resistor, feed the offset voltage to one end and the signal via a capacitor to the other end. Buffer if needed.
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>>902011
>I'm not too sure what you think the problem is
I was just asking. I'm still a beginner when it comes to embedded systems. Alright, I'll start experimenting with this, thanks!
>>
>>901914
You'll find that a lot of those little "car alarm" horns are self-contained, and only need 12V input to generate the tones.
>>
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i found this guy on YT if you want to know the worst electrican ever check hi videos he schocks himself in nearly every video

https://www.youtube.com/channel/UCJ0-OtVpF0wOKEqT2Z1HEtA
>>
>>902193
You don't have to post the link in every fucking thread. We've all seen him, we all know he's acting, it's not funny anymore.
>>
>>902193
hahahaha what a dumbass how did he even get a masters in microelectronics and his job as a product development engineer for a marine equipment supplier

lol i bet he shocks himself all the time at work too
>>
>>902011
The power supplies are giving me what's expected, the output of the amplifier also gives me what it's designed for. I'm then feeding that through a pot and not getting a tunable offset.
I also tried having the pot at one of the inputs being summed, which would work much better as the other way it's not exactly adding a tunable voltage offset but rather just taking part of the summed AC and DC signals.
The second option could work... maybe. It's a slow AC signal at times, which could mean at times it'll just charge up the capacitor; and it's a control signal which, if it gets cut off, breaks the loop.
>>
>>902193
He didn't know >>902199

get buttblasted son
>>
>>902193
>there are people who believe this isnt satire
I don't want to live on this planet anymore.
>>
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Hi, I guess this is the most relevant thread to my problem.

I have this old bike light that is shit - takes 2 D-cell batteries and has one small bulb. I guess I dont have to stress how useless it is but my dad is a sucker for shit for things for dollar store.

Anyway, I was wondering if I could convert it to have led(s) and maybe a different battery. High-end bike led lights are ridiculously expensive and I thought I could use this because it already has attachment, light reflector and usable shell.

What is the course of action here? I can solder but I dont know how to design it and what components to use.
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What do you think about this clock I'm about to make?
I don't have any microcontrollers bigger than the attiny85 so I put two shift registers in series, I already made a timer with just a 595 and a single module 7 segment display and worked just fine. I'm thinking programming this one will be a pain due the binary combinations being huge.
Should I buy an attiny2313 to run both shift registers per separate? Or will this work just fine when I program it?

Also, can you find any flaws I might've missed out?.

Thanks in advance.
>>
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>>902480
Picture related, first attempt with a single digit display and a single 595. The display I'll be using for the upgrade is also depicted.
The added problem will be multiplexing not with one, but with two shift registers.
>>
My in-ear headphones jack always gets loose and I have to throw out 10$ every time.
Is it worth it to repair it?
If yes, how?
Otherwise I will look for a Bluetooth in ear headphone soon.
>>
>>902502

headphones have plugs, not jacks. plugs never ever get loose. the thing you stick your plug into is the jack, and they do become dirty and loose with time. if your jack is loose, buying new headphones makes zero difference. if you didnt know all this already one might suspect mental retardation.
>>
I was thinking about making a pyrography pen from an old pc PSU. From what i read nichrome is good for the tips of the pen but I'm a bit unsure on how many V should i hook it up to so it doesn't completely melt or doesn't get heated enough. From what I've seen 5V should seems right but I don't know enough to trust google on everything. Not that asking strangers on the internet could make something go wrong...
>>
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>>902506
>plugs never ever get loose
Pulling facts out of your ass 101:
Never use definitive sentences, use adverbs like "rarely" to avoid getting caught.
Pic related, Philips earphones with a defective plug. To confirm the plug is damaged press around and wiggle it, if the earphones malfunction try this with other device or other jack, if they're still don't work properly when pressing the plug, disassemble, resolder and epoxy in place.

>if you didnt know all this already one might suspect mental retardation.
Go to be an annoying piece of shit somewhere else.

>>902528
V=I*R Measure the resistance and look for the amps for it to get at a certain temperature, calculate the voltage accordingly.

Also, somebody help me with this pls:
>>902484
>>902480
>>
>>901097
Solder on an appropriate connector to a tenergy battery charger/discharger.
>>
>>902529
>Pulling facts out of your ass 101:

dude, an intermittent connection is completely different from a ''loose'' plug. ask your mom to drop her panties to show you what ''loose'' actually means.
>>
>>902529
>>902529
Dude, a plug is to a penis what a jack is to a vagina.
Now, a vagina can get loose, but did you ever hear of someone's penis getting loose?
>>
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Is this badly designed? Actual voltage coming from regulator to the potentiometer is 6.4 volts.
I'm trying to add an offset to the sine signal, which I can tune with the potentiometer.
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>>902570
>Ur mum jokes
Do you realize this is a >18 website?
>>902573
Obviously the guy was referring to the cables inside of it, which got loose from the jack. It is retarded to think a solid object can get loose and so it is to assume someone can think that.
Also samefag.

>>902577
The reference voltage is usually set at the non inverting input in that case. If you do it that way it'll probably bring the voltage down or saturate it with negative voltage at the output.
>>
>>902577

add a cap in series with the AC source. should have an impedance at the desired frequency of 1K or less.
the 150K resistor should prob be lower. as is, you're dividing the 6.4V source by around 10 with the 15K feedback resistor.
also, it makes more sense to use the + input of the OP-AMP so you dont have to think in negative terms. connect the - to the output to make a summing buffer.
>>
>>902607
I want to divide it by 10. I need only a very small amount of offset, I might have to make it lower actually.
Could you expand on the cap at the AC source?

I was under the impression that the input for the summing amp is always fed at the negative input. Every website I've read suggests so, at least.
>>
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>>902612

like the 100u cap in this pic.
you can see the DC offset in the oscilloscope
>>
>>902570
Please leave this general. We really don't need cancerous people here.
>>
>>902638

dont call me general, captain.
>>
>>902643
Hownew.ru
>>
anyone here built a bottlehead crack before? is it very hard?
>>
How do i learn to code PICs
Code doesn't make any sense to me :(
>>
>>902664
If you're having an absolute hard time learning them, you could always pick up a course at your local university.
>>
>>902473
You'd probably put a bunch of white LEDs in series with resistors (Google this if you don't know, super easy beginner's thing) . Ideally you'd have a steady voltage instead of the drop-off of a battery, but unless you want to waste a bunch of power with voltage regulators it's not worth worrying about.

For a dollar store trinket I'd buy a new nice one, but that's what DIY is for.
>>
>>902617
No, I understand what you mean by a cap in series. I meant why do I need a capacitor at the input of the AC signal.
>>
>>902682

without the cap, the internal impedance of the AC source will appear as a resistance to ground in parallel with the DC circuitry. so, if you have a signal generator, it's like putting 50 ohms to ground, which will mess up the DC offset calculations completely.
>>
Whats up fellas?im making a 20v power source for one of my classes and ive got two things i want to ask. Anyone have any good ideas to add to it besides variable voltage? And how can i measure the current being leaked from the source?
>>
>>902686

current limiting is very useful feature coz it prevents a lot of burnt components

you measure current with an ammeter of course
>>
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>>900738
Hey guys, I need some explanation here. In an experiment we were to construct a full-wave detector circuit (pic related). I followed the diagram to the dot, and had tried multiple components, but the oscilloscope was still displaying a waveform that is for a half-wave detector.

To this day I still don't know what was the problem. Any possible reasons why I kept getting a half-wave output when it's supposed to display full-wave?
>>
>>902701
pic related also. This is the output when the probe was connected to Vout.
>>
>>902701
>>902703
You've fucked up somewhere. Can you post a photo that's good enough to show the diode directions?
What is the probe's ground connected to?
>>
>>902701
>>902703
It's possible one of your diodes is defective. The waveform you showed is what will happen if one diode is missing or won't let any current through.
>>
>>902705
>>902707
We were supposed to use a bridge diode. I tried doing it with single diodes but still get the same result.
>>
>>902701

wiring error
diode(s) pointing the wrong way
dead diode(s)
take it all apart, check all diodes ok, redo.
>>
>>902703
what did you expect?
this looks like a waveform id expect to see from that circuit.
>>
>>902711

nope, google full-wave rectifier
>>
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>>902711
It was supposed to look like pic related

>>902710
I wouldn't be able to do it again because there's not much time in the lab after doing an experiment :(
>>
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>>902712
youre right, i was wrong.

bad diode somewhere, then.
>>
>>902689
Yes but connecting an ammeter straight to a voltage supply could burn out the ammeter i just want to test the current leak before i do anything else. I understand that there are multiple ways to limit current, but dont most break down over higher voltages?
>>
>>902703
bad diode or connection.
remove diode #1, if no change, #1 or #2 bad (or backwards)
if the waveform disappears, #3 or #4 bad
>>
>>902717
>connecting an ammeter straight to a voltage supply could burn out the ammeter

you always wire an ammeter in series with whatever current you're measuring, not across a power source. also, if the supply can supply more current than the ammeter can take, you put a fuse in series.

>there are multiple ways to limit current, but dont most break down over higher voltages?

you use an element that can handle whatever voltages and currents are present. for example, an LM317 used in constant-current mode can handle 37V and 1.5A.
>>
>>902664
Pirate a book. Its called PIC micro-controller by mazidi. Read it.
>>
>>902837
That is such a shit book
>>
>>902839
Really? What's a better book then?
>>
>>902840
Idk. All I know is we used that book in my undergrad microcontroller class and it sucks
>>
>>902841
Well how do you know its a shit book if you have nothing to compare it to?
>>
>>902705
>>902707
>>902710
And in addition to these: if the AC source feeding the bridge was grounded from one end, then the scope ground can cause this.
>>
>>902473
get a 1watt or 3watt led of your color choice, a resistor of appropriate value, and a 9v battery, and through it in there. It'll be massively bright. You may need a heat sink and drill some holes to let air in to cool the led. Just search 3 watt leds, there's a gagillion of them out there and lots of videos of people doing shit with them.
>>
>>902664
you stop and learn superior AVR
>>
>>902664
Are you looking at C or Assembly code? Anything written in Assembly doesn't even make sense to the person who wrote it a few days later.
>>
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Re-posting from /g/

I received these digital logic ICs from my uncle a long time ago. In addition there are two analog ICs: LM339 op-amplifier and LM2902 comparator. I made a list of the parts and hunted the datasheets for each one.

>HEF4093 4 x NAND Schmitt-trigger
>CD4017 decade counter
>MC14017 decade counter
>HEF4053 3 x 2-input multiplex
>74F374 8 x flipflop(D), 3-state output
>CD4051 1 x 8-out multiplex
>SN74LS156 2 x demultiplex
>SN74HC14 6 x NOT schmitt-trigger
>M74HC164 8-bit SIPO shift register
>CD4029BC Binary/decade counter
>CD4019 4 x AND/OR select gate
>MAX507 12-bit digital/analog converter
>LM339 4 x comparator
>LM2902 4 x op-amp

I am interested in building some simple circuits with these digital ICs but I do not have much knowledge about the topic. What kind of circuit(s) could be realized with these parts? Could I do a light controller or a tiny solar charger controller?

Pic unrelated
>>
>>902873
Almost all of those ICs are very cheap and very easy to find. I don't really see the point of building your projects around your skewed selection of chips.
That said, in many non-critical uses you can replace random opamps and comparators with lm339/2902.
Find some olllld hobby electronics book (or online equivalent) for ideas about simple circuits using standard logic and opamps.

Opamps, comparators and possibly analog multiplexers might have use in a charge controller. 4017 is used in some toy blinking light projects.
>>
>>902816
Where im getting confused is with accuratley meausring the output current. Say my source outputs 10v with 100ma being leaked, i place a 10ohm resistor accross it. Will the current across the resistor be Vs/R +Is=1100ma and the voltage be 11v? And so if i want to measure the current leaked do i subtract my actual of 1100 from my theoretical of 1000? I know there is something fundamental here that i am just not seeing.
>>
>>902859
Then you stop that and learn superior ARM.
>8 bit
>2015
>>
>>902911
What is this 100mA leak current you're talking about? The current consumption of the PSU itself? Just take the PSU supply current before the current limiter and ammeter.
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>>902701
I suspect that you're grounding one end of the output with the scope when you should be using 2 probes (one on each side of the output) with the scope in differential mode.

If the input is unbalanced (i.e. one side is ground, the other side is +/- relative to ground), the outputs will consist of two half-wave signals, one positive and one negative, on alternating halves of the cycle.
>>
>>902875
Thanks for your suggestion.
>>
>>902480
It's not going to be a very accurate clock running from the internal oscillator.
>>
>>902664
https://www.lifeline.org.au/Get-Help/Facts---Information/Self-harm/Self-harm
>>
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>>902974
I knew that, I want to use this as a proof of concept for working with shit registers and I'll probably end up using it as a timer instead of a clock.
I tried it and it didn't work, after lots of continuity check on the board and other crap I just realized I forgot to connect pin 10 (Master reset) of both 595s to +VCC , I'm going to bridge them and see what happens.
I hope it works now, programming doesn't seems too difficult.
P.D: You fuckers could've told me >:(
>>
What's a cool and impressive beginner project I start to learn electronics and inventing? Completely new to this sort of thing.
>>
Hey /ohm/ I am starting my first DIY project and the first part is just a basic IR emitter and photo-resistor set up. Problem is that I cant tell if my parts are busted. If I put in normal LED's they work just fine, and the photoresistor cuts off current fine, but I think my IR's are busted, when testing with my camera I can see the ones in my remote but the ones I bought for this don't light up at all. I also used my multi meter and a whole range of resistors in case that was the problem and nothing works. Any tips for testing or any sources for reliable parts like this?
>>
Do you think running 2 adc channels, 2 pwm channels, and 4 I/O pins is enough to destroy my atmega328p?

am I going to be pushing the limits in terms of processing power running a 16mhz clock?
>>
>>903361
Those requirements aren't heavy at all, and with most microcontroller projects it's doing the calculations to decide what to output that takes up most of the execution, not the one line of machine code it takes to set an output register.

You should also be aware that PWM and ADCs are asynchronous hardware. CPU isn't what's toggling the PWM bits, it doesn't get slowed down. You can do other things with your code while waiting for the ADC to convert.

Microcontrollers are not "destroyed" by code that's too complex for them to execute quickly, they just don't do it as fast as you want.
>>
>>903346
Do you have a datasheet for your photo-resistor? They don't respond to all wavelengths the same, it may not react to IR at all.

What's your IR LED circuit like? Are you sure you didn't put it in backwards or give it too much or too little voltage?
>>
>>903404

thanks anon

I what I mean by destroyed is will I cause it to draw too much current and kill itself, in a rough estimate
>>
>>903408
> will I cause it to draw too much current and kill itself

No you will not.

When your PC's CPU gets hot because you're running a lot of programs it's because the OS decides it better speed up the CPU. A microcontroller like yours does not have an OS and runs a single program. It will not change clock speed unless your code tells it to, and it's almost always impossible to damage the chip by doing this.

Your microcontroller runs its program as fast as it can no matter how complex it is. A blinky LED and a fast Fourier transform both make the CPU run at the same speed and consume the same power. Delays are normally implemented as just a loop that doesn't do anything.
>>
>>903408

You flat-out can't fry an MCU unless you either exceed the maximum current allowable on one pin, or the maximum current allowable through ground/Vcc.

(I'm sure there's some weird exceptions to this, but I'm not aware of them.)
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What happens if you reverse a tantalum capacitor, besides it getting real hot?

I dessoldered them and soldered them in the correct orientation, but, man, fuck whoever decided it would be funny to put a stripe on the positive side and not on the negative, like everything else that has a stripe to indicate polarity.
>>
>>903439
Usually they fail shorted and catch fire.
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>>903047
>P.D: You fuckers could've told me >:(
Oh, it was that super funny memeshit schematic. I closed it immediately.

>>903439
Like the other anon said, they have a tendency to catch fire. To make things worse, the content is thermite-like stuff, so after you've provided enough energy to ignite them, they continue burning.
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>>903414
>A blinky LED and a fast Fourier transform both make the CPU run at the same speed and consume the same power.
I doubt this, arithmetic instructions probably use more power.
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>>903407
I have been following this circuit down to the letter and the place I got my LEDs from didn't have a data sheet for them, which was my bad, I just saw quantity and price and wanted them. I do know they are both 940 nm wavelength and that it is a 1.2-1.3V forward voltage.
>>
>>900738
>>
Get yourself an Arduino board, they are a great way to learn how to use electronics and (fairly easily) make almost anything that you want to! Take a look at their website and see what's to offer.
>>
>>903542

if you dont see your IR LED on your camera, then it's not turning on. either it's dead or wired backwards. maybe you can take an LED from some old remote control.
>>
In general, how do you go about powering both low voltage and high voltage things from a single supply? Say for example I have a single 12V supply and I wanna get 4V for my microcontroller, and the full 12V for a DC motor. A simple voltage divider with 2 resistors doesn't seem very suitable.
>>
>>903657

you use a regulator to step down the higher voltage to the lower ones. a 7805 for example will take in 7 - 30V and give out 5.0V. an LM317 is adjustable, so you can get out any voltage from 1.2V to 35V.
>>
>>900738
Is this a good deal?
http://www.aliexpress.com/item/UNO-R3-KIT-Upgraded-version-of-the-Starter-Kit-the-RFID-learn-Suite-LCD-1602-for/1318648074.html

I'm looking to get into using an Arduino to make additional buttons and to generally mess around with.
>>
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Quick question from someone with virtually no knowledge of EE besides (basic) soldering skills:
I'm trying to make a VGA to SCART adapter that will take a 15kHz (240p) RGBHV signal and convert the horizontal and vertical sync information into composite sync (RGBS).

I've got most of the connections worked out from diagrams on google, and my apologies for the super-shitty MS paint circuit diagram, but I'm trying to work out a way to integrate a micro USB B port in case this circuit is used with any VGA source that's not VESA compliant (ie. doesn't supply 5v on pin 9) so as to power the IC in lieu.

The system I've got here to check is pretty rudimentary; lighting up an LED if there's 5v on pin 9- telling me to plug in a phone charger and flick the switch otherwise, but someone on /g/ suggested using a relay to switch over automatically.

Is it worth integrating a relay? If so I'm not familiar with their usage, so could I subsequently ask you to spoonfeed me the correct type and pinout?
That and any other general advice would be much appreciated.
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>>903786
>Is it worth integrating a relay?

No absolutely not. A voltage isolator is just a pair of diodes. Any general purpose ones will do (1N4something). With this circuit the 5v out is drawn only from the higher of the two sources. If there's no VGA 5v that will be the USB. If there's power from both of them it will draw from whichever is a few millivolts higher. This could mean drawing from the USB even when there's 5v from the VGA, but I don't see why that would be a problem.
>>
>>903798

the 74HC86 is supposed to work down to 2V so the 0.7V diode drop shouldnt hurt. as long as the guy doesnt substitute for the TTL part, or the 74HCT86 part.
>>
>>903798
>>903803
So basically, substitute the switch for two converging diodes and I'm good? Well that is certainly a hell of a lot easier.
Thank you for the help.
>>
>>903803
Or just get Schottkys
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>>903721
so if all i need is LM7805 to drop voltage why do people suggest UBEC/SBEC if 7805 can do it much cheaper? is it because you need to add heatsink with 7805?

not same person btw
>>
>>903838
>>903838
UBEC/SBEC are switching (stepping) regulators. The other guy shouldn't have used the phrase "step down" when talking about 7805s or LM317s. Those are LDO regulators. You can think of an LDO regulator like a smart series resistor that changes in resistance to get the right voltage drop across itself to keep one side at a constant voltage. They're much less efficient than stepping regulators because they're burning off the excess Vdrop*I as heat. The amount of energy they waste as heat is about equal to the difference between input and output voltages multiplied by the current draw of the load, and they can only get so hot before giving up.

If you use a 7805 or LM317 to go from 12v to 4v the regulator itself will be using twice as much energy as whatever it's powering.
>>
>>903851
oh right so its only good for clipping off a few volts 12V input 10V out for example.
>>
>>903721
>>903851
Thanks guys, very helpful. I see everywhere people use 7805 with 2 bypass capacitors, is this also strictly necessary when using only DC?

>>903852
Or bigger voltage drops but with very low amperage, I'd say.
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>>903875
Those are generally needed for the regulator to stay stable even if you're running it ofs a battery albeit much smaller than if you regulating rectified AC and the same output capacitor needs to be there regardless of the input.
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>>902912
8 bit is still cheapest. Sometimes you don't need more.
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>>903838

if using a 7805, or similar, causes too much heat, or too much drain on batteries, one simple way to get a 12V switching regulator is from a thrift store car adapter for a phone. cost is $1 or less. inside it should be a tiny circuit board with a switching regulator chip.
>>
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Hey guys, I'm making a 4-layer PCB and am now finishing it up. Right now I'm laying down the ground planes.

I want the thing to be as EMC-friendly as possible of course, so from what I understand I should try and fill pretty much all larger areas with copper and put it on ground potential.
Now here's my question:

My circuit is designed to be flexible in terms of power supply; I can either supply positive and negative voltage symmetrically, or just positive voltage asymmetrically. As a result I have three different ground potentials (Ground from the power supply, and virtual signal ground for in- / output

With a symmetrical supply this is not an issue since then all ground potentials are the same at 0V. However, with the asymmetrical supply I have power ground (earth) at 0V and the signal ground at 12V.

My question is, after having routed everything, do I fill in empty areas with power ground, or do I shield areas with signals by filling empty areas around them with signal ground?

Thanks in advance.
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>>900738
hi guys, turns out I have to design and make an amplifier, I can choose from class B and AB, wich one is better or easier? where can I find info on how to desing one?
>>
>>904071
Class AB has lower crossover distortion, class B has slightly lower quiescent power consumption. Class B is bit easier to design.
Google should offer something with "class ab amplifier design". There are books dedicated on the topic as well.

>>903913
Filling board with inactive copper isn't usually a particularly effective way to reduce EMC. Think how the currents flow and concentrate on reducing the current loop areas. Add filter capacitors/inductors to keep noise in limited areas.
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>>904075
I'm not filling them with inactive copper, but with a ground potential. I want to know which ground potential (0V from PSU or virtual signal ground) I should use for certain areas.
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I'll just leave it here
>>
Hey, where can I get resources on building a basic Adder and understanding it (On a breadboard)? Thanks.
>>
>>904618
http://www.nand2tetris.org/
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>>904212
I meant copper which isn't actively carrying current, but just sits there as a shield. Well, whatever.
You need to consider what is the most important thing for you. For example, the input stage doesn't (probably) radiate much shit, but is prone to interference. So you preferentially shield it with the input stage's ground. Or if you want to reduce the emissions of the power stage, you use its stiffest node as a shield. In this case it might be the most negative supply (= ground when using a single-ended supply). You don't need to use one single ground plane for the whole board.
If you insist on using one plane for the whole board, you choose between the emissions (power stage) and input shielding (inputs). If you're more worried about the emissions, use the power stage ground (or "the stiffest node").

>>904618
https://en.wikipedia.org/wiki/Adder_(electronics)
http://www.instructables.com/id/4-Bit-Binary-Adder-Mini-Calculator/?ALLSTEPS
Seriously, learn to google.
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I just built this simple circuit on breadboard and it seems to work. It uses a digital CMOS switch IC to control the state of two oscillators (off/flashing). Kind of new to this stuff, please correct me if I'm doing something wrong.
>>
>>900738
How much power can a emergency crank radio generate at 5V and how feasable is it to charge a phone with this power?
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>>904689
Looks good. For a minute it looked like you didn't have you schmitt oscillators right, but the feedback loop goes through the demultiplexer.
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I also posted this in another thread but then realised this thread would be more appropiate:

I have a LED panel that I plan to mount into a custom nightstand. I want to add a potentiometer to it, but my knowledge in electronics is limited. This is a picture of the transformer it comes with. Is this feasible or am I being excessively dumb?

Where would I place the potentiometer and would I need any extra components?

This is for a class project of furniture design so they didn't teach us electronics.

Thanks in advance.
>>
question about programming an atmega328p

Can I assign an "uint8_t" a value in binary, hex, decimal or all 3?

if i assign it binary or hex, can I read it as decimal?
>>
>>904775
A potentiometer is a terrible way to dim an LED in general and will be even worse with that power supply. LEDs don't respond linearly to voltage like incandescent bulbs. Half a volt below the recommended level and they don't turn on, half a volt above and you significantly reduce their lifespan. LED Dimming is normally done with pulse width modulation. That's where you're switching them off an on faster than the human eye can see and using duty cycle to control brightness. If they're on 70% of them time and off 30% of the time it looks like 70% brightness and so on.

There are a lot of PWM circuits online using chips like the 555. You'll have to use a separate power supply to run them because the one for the LEDs you pictured outputs 30v to 40v. Use a MOSFET to switch your LEDs off an on with the PWM signal.
>>
>>904795
What compiler are you using? Hex is part of the C standard so lines like this should always work:
uint8_t X = 0x15;
Binary isn't part of standard C but it's often included anyway, so some combilers will accept this and some won't:
uint8_t Y = 0b01001111;

You can always write a macro to accept binary if your compiler won't take binary input.

In either case it doesn't matter how you enter the number. It's value in memory is the same. The compiler doesn't remember or care what number system you've used with numerical variables from one line of code to the next.
>>
>>904803

ok thanks

i'm using AVR Libc. Pretty sure it should take binary
>>
>>904795
You're fundamentally misunderstanding how it works.

In C, it's not binary, hex, /or/ decimal. It's an unsigned integer, which is an abstract concept of a number.

When you assign it a value, you're asking C to take whatever expression is to the right of the = (RHS), work out its value, convert the value to a format that can go in a uint8_t, and assign the variable on the left of the = (LHS) that converted value.

So when you write

> uint8_t x; x = 0xAB;

What actually happens is that C takes the hexadecimal literal "0xAB", converts it into an integer value, casts that value to uint8_t, and stores it in the variable labelled x.

Once it's in x, it's a number. You want to treat it as binary you can: if you use it on the RHS of an operator that wants binary ( ||, for example), C will treat it as binary. You want to treat it as hex, you can do that too (printf("%02x",x); for example. But it's not really hex, decimal, octal or binary, fundamentally it's a number.

That it works out as being stored and manipulated by the processor as an eight-bit value is an implementation detail. That it It has to be equal to or less than uint8_max, and uint8_max is 255 (which just happens to be 0b11111111) is again an implementation detail. *You're prohibited by the standard from knowing or caring about these things*.

Your code could end up getting compiled for a trinary water clock, and so long as you followed the C standards, it'd still work.
>>
>>904815
>You're prohibited by the standard from knowing or caring about these things
Huh? Isn't the whole point of those uintX_t types that they have a fixed, known number of bits?
>>
>>904823
The point is that they're integers with limits that are the same size as something with a fixed, known number of bits.

But all you're allowed to care about is whether or not uintX_min << x << uintX_max.
>>
>>904823
Shit wording on anons part. The point is: the C standard says you don't have to worry about implementation details because it is guaranteed by a standard compliant compiler that if you ask for n-byte wide memory allocated you get n-byte wide memory allocated and here are your options of n = [1, 2, 4, ...]. The standard sure as fuck doesn't prohibit anything.
>>
>>904832
If you go outside the standard, you end up in the exciting land of "unspecified behaviour".

Sure, the standard doesn't prohibit you from writing code outside the standard, but it does say that the compiler can do *literally anything it likes* if what you're doing is not something the standard specifies.

http://blog.llvm.org/2011/05/what-every-c-programmer-should-know.html
http://blog.regehr.org/archives/213
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Hi guys. How do you get a module to work with your Arduino or Teensy?

I've been reading some guides and tutorials for getting started with your Arduino, and they're all really nice for getting an LED to blink, or adding an Ethernet cable to your Arduino, but what if I order some random module from China or I salvage a module from an old toy (e.g. vibration motor) -- how would I get it to work from there?

Would I start with the datasheet?
>>
>>904830
"The typedef name intN_t designates a signed integer type with width N , no padding bits, and a two’s complement representation. Thus, int8_t denotes a signed integer type with a width of exactly 8 bits.

The typedef name uintN_t designates an unsigned integer type with width N . Thus, uint24_t denotes an unsigned integer type with a width of exactly 24 bits."
>>
>>904830
>>904832
i always thought c only provided the basics, int, long etc and then int_x was platform dependant typedef in some header file.
so you can't rely on it cross platform you would need an appropriate header for that processor that defined it correctly?
is that right?
>>
>>904871
The exact-width types were introduced as an optional feature in C99, and were adopted by C++11.
>>
How do I get a small DC motor to reverse direction at full speed? I have a circuit with attiny for pwm, mosfet and h-bridge, and whenever I flip the h-bridge switch the motor starts to jitter back and forth. This only happens above certain power levels, and I can only stop the jittering by dialing down the pwm and then back up again. Any idea what's happening here?
I don't have a flyback diode nor a bypass cap on the motor, should I?
>>
>>904882
Ty Dennis
>>
>>904863
A datasheet or rather a description of what the module is and what it does, and how it does it, is the first step.

Then find ways to implement that with your board. See if anyone else has done it in the past. Check if there are any libraries available for it.
>>
>>905166
nvm, all problems are gone when I actually put some load on the motor.
>>
So I have this 9W LED bulb and I was wondering if I could modify the circuit to add a dimmer, I would really like to be able to dim it or at least to have two or three different power modes but I don't really know where to start. I'm going to dissassemble it and start thinking about a feasible circuit. Any ideas?
>inb4 you will kill yourself
I have experience with this sort of things.

When I opened it I discovered a (7W pad) left unconnected, maybe I could connect the wire from the 9W pad to that one with a switch. But my fear is that pad is for other models with a different PSU, and if I connect it the PSU in this model will kill it. What do you think about this?
I'm going to try and map the traces.

By the way, the circuit is totally enclosed inside the plastic, there's no way of taking it out without a hacksaw, all I have are those two wires.
Maybe I could put a mosfet in betweed to do some PWM with an external circuit.
>>
Can anyone post a circuit diagram for a simple fm transmitter with an audio input and not a mic? Preferably with a variable capacitor.
>>
>>905256
>Maybe I could put a mosfet in betweed to do some PWM with an external circuit.
That's what I was gonna say. I think it'd work.
>>
>>905256
Yeah, after marking the traces the 7W pad disconnects the inner ring, ending with just the outer one, which would presumably end up overpowered.
However I've still got my hopes up, I was thinking about adding a switch and use the pad to connect only the inner ring. I would have to pick a resistor to do so, but I don't know the current rating of the LEDs or have any information about the circuit powering them, although the voltage must be around 50 volts assuming they're single LED diodes.
I'm going to use my scope to check that by myself.
>>
>>905256

if you wanna dim, you use a dimmer.
>>
>>905259

FM can be frustrating if you dont have a frequency counter that can do 100Mhz. you can get FM car x-mitters with digital displays for frequency for about $3 at the thrift store.
>>
>>905266
I wanna do something myself. I've found a circuit online and the guy who posted it said that the frequency is very stable.
>>
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>>905264
This is a non dimmable bulb, so I guess it takes special modifications to do that.
I'm thinking about just using a resistor and a switch to change from the full to the inner ring, the power of the resistor is 2W I think.

I would need a power source for the mosfet driver circuit and with just 16mA coming out of the main one I don't think that is a good idea.
>>
>>905278
Okay, this is it after the mod without the case. I used two 470 Ohm 1w resistors.
Now the question is, will it blow, let's find it out.
>>
>>905292
It worked fine but after switching around 10 times I managed to blow up two LEDs and probably damaged some others since the resistance values are not consistent. The MOSFET would've had a similar effect.
My bet is the PSU relies on the LEDs drawing some current to fix the voltage, the brief moment when the contacts disconnect inside the switch and reconnect again is enough to bring the voltage up and pop the LEDs.

How could I solve this voltage peak problem? Drawing power while the switch is moving is one possibility, but I don't know how to do that. The other one is to add a filter like an inductor or to add a part of a circuit to cut out that voltage peak.

As always, if ain't broken, don't fix it.
>>
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Sup /ohm/

I'm new to electronics so I bought a JYETech function generator to practice my soldering.

Where do I get raisin-core solder? I need it to start soldering.

I've looked everywhere but all I can find is that knock off 'rosin' shit.
>>
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>>905341
Surely your kidding. Rosin is the correct stuff.
>>
>>905344
No. read the fucking instructions.

I need raisin core, none of shitty rosin stuff.
>>
>>905345
>raisin not rosin
well guess you won't be building that kit. just toss it in the trash.
>>
>>905341

To get good raisin core solder you need to buy from a real nice vineyard. California or Italy are known for having the best in the world. It's worth paying extra.
>>
>>905269
> the guy who posted it said that the frequency is very stable.

forget the guy. the guy is a an ignorant cunt. there's no such thing as a stable LC circuit. you just have to approach the circuit with your hand and the frequency changes. if you try to adjust the frequency on the pot, the metal screwdriver changes the frequency as you touch the knob. you have to get a nylon screwdriver. i bet you didnt even know they existed. do you think *the guy* has a nylon screwdriver? no, he's diaper-wearing cunt on the internet spouting old-people garbage.

what you want is a modern frequency-synthesized FM oscillator, microprocessor-controlled, digitally-tuned. no screwdrivers required, nylon or otherwise. take my previous advice, please, before you find yourself wearing adult diapers as well.
>>
>>904775
You can't dim an LED lamp without understanding how it works. You probably can't dim it "from the outside", i.e. without modifying the driver circuit.

The LEDs themselves can't be dimmed by varying the external voltage. Their voltage-current curve is highly non-linear. Below the threshold voltage, you get nothing, above the threshold voltage, they act like a short circuit (i.e. they'll draw as much current as is available, and if that's too much they'll burn out).

Indicator LEDs (in the milliwatt range) are current-limited by using a resistor. More powerful LEDs tend to use a switching regulator (buck converter), as that avoids wasting a significant chunk of power.

Any kind of active circuit will probably require a fixed voltage. To the extent that it accepts a variable voltage, it will try to maintain the design intensity regardless of supply voltage.
>>
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I have a monitor with bad caps, I’ve replaced the obviously blown ones and I’d like to test the other ones. Would you guys recommend the dedicated capacitor tester or the multiple component tester.
>>
>>905434
If you're going to be testing caps, might as well replace them. You can only test them by removing them.
>>
>>905434

it looks like both of those only measure capacity, whereas you wanna test ESR, which is what distinguishes a dying capacitor. ESR meters can be bought, made, or simulated with other equipment (see https://www.youtube.com/watch?v=115erzCCxgE)
>>
Thoughts on this multimeter? http://www.aliexpress.com/item/Multimeters-Mastech-MS8233E-Auto-Manual-Ranging-Digital-Multimeter-with-Temperature-Measurement-Digital-Multi-Meter/32390131220.html?ws_ab_test=searchweb201556_1_79_78_77_80,searchweb201644_5,searchweb201560_6
I know lots of people say to not cheap out on a DMM but spending $100+ is not an option
>>
>>905515
I would hunt through local pawn shops before getting a questionable meter from china nobrand. Any halfway decent one you find in a pawn should either work perfectly because it's a valuable piece of equipment that was treated well by the previous owner or it should be obviously broken because the previous owner was an idiot. non-chain pawn is better, the fancier the place is the more they bump up prices towards new retail.
>>
this book any good?

anything else worth checking out?
>>
>>905325
The circuit voltage output is very unpredictable, going all the way up to 300 volts when nothing is connected, it has an inductor (not an stepdown transformer) and an IC, no idea what it might do. I wanted to connect a 10W 30 volt LED to replace the LEDs, but I have no way to calculate the voltage or current or to modify it in a propper way unles I completely map the circuit (IC included).
>>
>>905575
This is the PSU, I forgot to attach it.
>>
>>902199
>>902193
>>902361
Epic samefagging
>>
>>902573
Actually it can.I have a micro USB cable ,the plug got lose because the wedges were broken due to repeated usage
>>
>>905577
That doesn't look anything like a power supply. Probably just a rectifier with a voltage regulator. Search what that IC is for. I can't discern the number from this.
>>
>>905571
Yeah, that book is one of the top books recommended in the OP.

Read the OP for more.
>>
What do i need to make a USB hid gamepad/joystick? I'd like to take arcade controls and make a USB stick for a raspberry pi. I've found the ultimarc ipac2 board but that seems pricey, and i want to learn this anyway. Do i need a micro controller of some sort? I have no real idea where to start.
>>
>>905575
Start by finding the IC datasheet. There's a reasonable chance that you need to change only one resistor.

>>905596
It looks like a very typical unisolated offline step down switcher - without inductor.
>>
>>905624
https://github.com/NicoHood/HID *.

Your BoM will be, approximately:
1x Arduino knockoff ($5)
Arcade controls
Wires

You'll have to write the core-loop yourself, but it's just glue code of the order of while(x=wait_for_input){do_action_for(x);}

* I found this on http://lmgtfy.com/?q=arduino+hid
>>
>>905596
>>905627
Sorry, I removed the inductor to show the resistors and the traces behind it. The pins on the right are disconnected.
>Search what that IC is for. I can't discern the number from this.
>Start by finding the IC datasheet. There's a reasonable chance that you need to change only one resistor.
I wish, but I tried that and CL1501 only brings up low noise amplifiers with a different package, I'll try some more just in case.

I also tried to power a row of 6x1W power led's to see what the maximum current would be, it was only able to output 0.16Amps and it was squealing quite a bit.
>>
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>>905666
I couldn't find a real datasheet either, but apparently it's made by Chiplink semiconductor and it's a current mode switcher for LEDs. Pic related.
So, you can probably adjust the LED current by changing the resistor between the CS pins and ground. Voltage isn't adjustable.
>>
>>905684
Oh, that ROVP might be overvoltage protection. Either way, adjusting the current sense resistor should be your first option.
>>
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>>905653
I didn't even think of arduino, just assumed that would be overkill. ThAnks breh
>>
>>905686
>>905684
Oh man, I love you. That circuit looks exactly to the one I have. I'll report back with the results.
>>
>>905692
I've found this, luckily enough it isn't written in ching chong, it seems to be a very similar if not the same exact IC with another name, I changed the resistor at pin 2 but it obviously did nothing (before finding this), I should have changed the one at pins 7 and 8, which is what I'm doing now, however the resistor is a combination in parallel of a 3R3 and a 2R2 resistors, so this is 1.3 ohms.
http://www.bpsemi.com/pdf/BP2831A/BP2831A_EN_DS_Rev.1.0.pdf
It even provides formula to calculate the current, I'm not sure if this is the best way to do this, but I'll give it a try, although the only resistors I have with values so low are huge power resistors.

So I've changed the resistors and the thing barely lights up, I read 36 volts on the meter, and the LEDs are very dim, maybe I managed to damage something, I'll keep trying.
>>
>>902577
What app is that?
>>
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Can I solder a standard 3.5" audio plug to this ancient headset without blowing up my soundcard or do I need some sort of amplifier?

There are two rather big speakers marked
"0.5W 8Ω"
>>
>>905966

nothing's gonna blow up but you wont hear anything unless you put your ear right next to it. you definitely need an amp.
>>
Hello, friends

I have a quick question -
Is there an obvious reason as to why you wouldn't be able to use a darlington transistor series to switch a big 220V supply from a small 5v microcontroller output?

This is only hypothetical, but I'd like to know what the reason is to further my understanding.
>>
>>906166
if the part can handle the voltage then sure
>>
>>906166

If you mean 220V mains, it's not doable because it's AC.

If you actually mean 220VDC, it's doable, assuming appropriate ratings on the switch and a few considerations to keep the microcontroller's output intact, but it isn't preferable. For safety reasons (including that of the microcontroller), you usually drive your switching device through an optocoupler.
>>
>>906170
Oh, alright. Thanks!
>>
>>905166
Ended up adding a flyback diode anyway and it runs much nicer now. Esp. in the lower pwm range.
>>
Can a shortcircuiting USB device fry my computer? USB has surge protection right?
>>
>>900738

Anyone know any consumer products that use Altera Cyclone 3, 4, or 5 chips?
>>
I'm trying to set up a humidity adjuster for my room that uses Adafruit trinkets hooked up to humidity gauges scattered throughout the room. The trinkets read the humidity then send the amount to the Raspberry Pi, which then turns a humidifier on or off.

I keep seeing people mention the powerswitch tail, but I've also read that it's rather noisy. I looked into mechanical and solid state relays, but I don't know which one I'd need control mains, or how I'd go about hooking it up.

I found this (https://www.sparkfun.com/products/100)

I just want a way to switch mains power on and off with a Raspberry Pi.
>>
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> USB has surge protection right?

if you mean short-circuit protection, yes unless it's a very cheap computer.

> I just want a way to switch mains power on and off with a Raspberry Pi.

relays are ok except they usually require a fair bit of current. a better, quieter alternative is an opto-isolator driving a Triac.
>>
>>906313
FPGAs aren't exactly common in consumer stuff to begin with.
What's the point of this exercise?
>>
>>901048
The whole 12V?
>>
>>906439

Saw some defcon talk on youtube were a guy flashed one with bitcoin mining software through JTAG
>>
>>906319
>I keep seeing people mention the powerswitch tail, but I've also read that it's rather noisy. I looked into mechanical and solid state relays, but I don't know which one I'd need control mains, or how I'd go about hooking it up.
1. either mechanical or solid-state relays can control stuff run off of mains electricity
2. you just buy a relay that has an output rating for the voltage and current you want. There is two contacts you place in series in the AC line you want to control, and two or three logic contacts.
3. mechanical relays click when they turn on or off
4. solid-state relays make no noise at all when switching
5. sparkfun sells a few solid state relays; one is product # 10636 ,,,a much bigger one is product # 13015

warnings to research yourself:
6. "DC" things like light bulbs and heating elements can be connected directly, but relays need circuit protection when used with inductive loads (like motors).
7. relays (either mechanical or solid-state) cannot be used with PWM to produce a dimmer or motor-throttle effect. If you attempt to make a relay switch (either on or off) for a very short period of time, it may stay on too long or fail to respond totally.

Pic related is the usual cheap China-generic solid-state relay breakout.
It has a LED that light up when on (which can be helpful) but the current capacity is kinda low--for some reason they only like to use 2A relays.
They may also have some circuit protection present but it's risky to rely on that (add your own).
>>
Hey guys, have any of you read any of these books:

Inductor Handbook
Capacitor Handbook
Diode Handbook

I have looked online for a "free" copy and I can't find them. I'm not good at finding books online desu
>>
>>906586
Wow, people are still taking buttcoins seriously? I also thought the time of profitable FPGA-based mining was over a long time ago.
>>
>>906726

If you can score a usable board cheep enough, why not just make it as a novelty
>>
>>900738
I'm seeking for a good ARM Cortex M0 + SWD debugger to program a DA14580 chip.

Anybody knows about something like that?
>>
>>906729
As long as you realize you'll be losing money just from the FPGA's power consumption alone.

>>906732
Depends on what development environment you're going to use. Go look at OpenOCD's list of supported interfaces, the cheapest FTDI-based ones go for as low as ten bucks. If you want something that works with commercial toolchains, J-Links work with pretty much everything, but the base model costs about $300 (the edu version is a lot cheaper, but keeps throwing up nag screens).
>>
>>906670
Those don't sound like books. Probably some handout handbooks from somewhere. If you want to read about those things, look for a book on electronic devices.
>>
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Small Stupid Ohm Question

This -/+ triangle symbol is just an op-amp with the T-bridge topology serving as a feedback, right?

I could use something as simple as LM386 as the component of choice there, right?
>>
>>906757
Yes it does look to be a simple OP-amp. The op-amp that you use would depend upon your requirements LM386 is for low voltage audio application, so if the specification fits your requirement, then it should work.
>>
>>906758
Purpose would be a battery powered drum machine so it seemed like a logical component to pick.
>>
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Can someone help me with my inexperienced problem? >>906855
>>
>>906756
http://www.amazon.com/The-Inductor-Handbook-Comprehensive-Applications/dp/0962852546
>>
Daily reminder tubes don't improve audio quality any more than semiconductor devices and tube amplifiers are snake oil.
>>
>>906757

the LM386 is a specialty chip with a funny configuration. for example, gain is controlled by wiring a circuit between pins 1 and 8, which is pretty unique way of doing things. it might work in that situation, but it's far from guaranteed. use a proper OP-AMP like an LM301, 741, LM324, TL081, etc.
>>
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>>906886
Daily reminder that opinions are opinions, and if you are going out of your way to shitpost like this, you prolly have bigger things in your life to worry about than things other people are doing.
>>
>>906886
>Daily reminder tubes don't improve audio quality any more than semiconductor devices and tube amplifiers are snake oil.
yea but,,,,,,, not really. (Ive posted this before, but anyway)

Back when tube audio amps was the only kind, music recordings were mastered to play properly on tube amps. There was way more dynamic range left in recordings, because tube amps didn't clip hard when overloaded.

During the 1960's, transistor audio amps became the "hot new thing". As transistors dropped in price, studios stopped engineering commercial recordings for tube amps and started engineering them to play well on transistor amps. And that involved flattening the dynamic range of the music, because a transistor amp gives massive distortion if it is overloaded for even a tiny moment.

TV's carried on longer with tube audio however because TVs needed high-voltage sections anyway, for the RF tubes that there was no transistor substitutes for. So most of the way through the 1970's (in the USA), TVs still had tube audio amps in them. And TV broadcasts were still audio-engineered for a much wider dynamic range of sound. (-this is mainly the time I remember the "tube audio" sound from-)

Nowadays, commercial music is engineered to play properly on typical transistor amps. The dynamic range is never left in it.
So even if you play a modern recording on a tube amp (capable of a much wider dynamic range) you don't hear any difference.

If you played a recording mastered for tube audio, on a tube amp, and then on a transistor amp,,,, you would very much hear the difference. And you'd probably agree, the tube audio one sounds way better.
>>
>>906952
>If you played a recording mastered for tube audio, on a tube amp, and then on a transistor amp,,,, you would very much hear the difference. And you'd probably agree, the tube audio one sounds way better.
That's only true if the cut off range of the transistor is ever hit. They sound exactly the same if you use proper semiconductor devices. Now days we have much better semiconductor devices and can easily make certain that the cutoff is never hit for any song we want to play. Even older songs made for tube amps. They have the same characteristics except the cutoff. If you never reach the cutoff, then it's snake oil.
>>
>>906957
The recording industry is still full of pants on head retarded 'Engineers' that hard compress everything to 1111111111111111.

They also have a hearing loss problem in their industry. One generation of old ass retards trains the new and tells them its supposed to be ear piercingly loud. Then that's how they make it.

I just listened to a song on a reel to reel and my jaw dropped. It had been so long since I heard dynamic range I was starting to think ny ears were damaged.

16 bit also isn't really suitable. I cant wait for 24bit to be widely adopted.
>>
>>907009

you are full of shit
>>
>>907013
Naw dawg
>>
>>907013
http://www.ronpellegrinoselectronicartsproductions.org/Pages/EnemiesOfOurEars.html
>>
>>907013
The Loudness Wars are real and well documented with plenty of evidence.
>>
>>904624
Thank you for the reply, good to know my thinking went in the right direction.
Well order the board next week and show you guys if you want.
>>
>>907009
>16 bit also isn't really suitable.
Yes it is.

>the effective dynamic range of 16 bit audio reaches 120dB in practice ...
>120dB is greater than the difference between a mosquito somewhere in the same room and a jackhammer a foot away.... or the difference between a deserted 'soundproof' room and a sound loud enough to cause hearing damage in seconds.
>16 bits is enough to store all we can hear, and will be enough forever.

https://xiph.org/~xiphmont/demo/neil-young.html

>I cant wait for 24bit to be widely adopted.
You'll be waiting a while, because it takes more space and offers no benefit.
>>
>>907009
>One generation of old ass retards trains the new and tells them its supposed to be ear piercingly loud.
It's nothing to do with hearing loss, it's basically to try to stand out on radio.
>>
>>907063
What is this "radio"?
>>
>>907065
Something that's still commercially significant.
>>
>>907063
No. Radio stations have their own compressors. This is what you get out of professional high end mixing guys. Its shit. Loom up loudness qaes and hearing loss in audio production. Its a big problem
>>
>>901386

Is there a part number on the MOSFET?
>>
>>907009
>tfw Boston will never record a new album
>>
>>907122
You're saying that like it's a bad thing.
>>
>>900738
Ohm... Im not much of a tech guy. I understand some stuff and what not..

I was wondering. How long can you span am Ethernet cord before it starts slowing down the internet connection? I want to add an ethernet cord to an extra bedroom and ive got my router as close as possible. But is running like 30 feet of ethernet cord gonna slow down the connection speeds because of the resistance of the wires? Is there a better way of doing this?
>>
>>907115
lts a regulator-rectifier.. The mosfet its self is covered in the epoxy. And the unit has no stamped markings I could find on the outside.
>>
>>907389
Cat 5 can go 300 feet. Cat6 can go 600 feet. The length of the wires and the resistance doesn't effect how long it takes for packets to get from your router to PC. Too long of a cable and you start dropping most or all of your packets because the electronics in the router aren't strong enough to overcome the capacitance between the differential wires.
>>
>>907395
So how do I determine if the length is too great for the router?

If it helps any. Its a netgear model; WNDR4500v2
>>
>>907398
You check for packet loss from the computer to the router (usually by pinging your router from the computer)
>>
>>907401
But that requires me to have bought the length of wire?
>>
>>907406
You won't have any problems with a 30 foot Ethernet cable. Stop worrying about it.
>>
>>907406

maybe look into calculating the loss. I know with fiber optic cables you can
>>
>>907398
dude, its 30 fucking feet. You will be fine.
>>
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i'm looking into oscillators at the moment and there is one thing i can't really get my head around: how can i safely predict whether the circuit is going to oscillate or not?

pic related is one of many i tried and it worked at around 8 kHz like the simulation indicated. now when i change values, presumably of the tank circuit, and it doesn't work, how do i know WHY it doesn't work with the chosen values? what are the characteristics that i have to keep in mind here?

probably L/C ratio,resonance frequency, working point, input/output resistance and capacity of the amp, open loop gain and whatnot. but i don't really know how to put all that together
>>
>>907459
A simple rule of thumb would be that the tank coil (or capacitor) should have a reactance of around 100 ohms at the oscillating frequency. It isn't horribly critical, but something like 10k or 1 ohms won't work in normal circuits.
>>
>>900780
step the 3.5V up. If you don't need much current, just use a diode/capacitor doubler.
>>
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Hey /ohm/, Could someone help me understand this circuit or point me at the right reading material to understand it? Very much an armature.

It's the steering control from an RC car, the only electronics are the ones that are visible the rest is gears and a stopper that just prevents the motor from spinning any further. I guess the capacitor is there to divert the current somehow to stop the motor from trying to keep turning and burning out?
>>
>>907689

looks like 2 coils in series and a capacitor in parallel with the motor. together they make a T-filter to suppress electrical noise created by the motor's armature/brushes. the reason you want to suppress noise is so it doesnt interfere with the radio receiver on board.
>>
>>907708
Okay, but what stops the motor from burning out?
>>
>>907725

nothing. if you apply too much voltage, it will get hot and fail after some time. since this is a battery operated device, this should never be a problem coz, if you had 4.5V of power, you would use a 4.5V motor. if you stalled the motor, it will also be protected by the fact that the batteries cant supply a lot of current for an extended period. or you'd use a fuse in line with the motor or batteries.
>>
Hey guys, I want to make a gift for a friend that's basically just a styrofoam block with a flashing LED in it. I know absolutely nothing about LEDs. What do I need to get/know? I'm trying to emulate just a circular flash, like an eye blinking.
>>
>>907737
Ahhh okay, well the system ran at 6v. So is the coating of the windings of the motor are just able to handle any heat that the 6v could generate. I guess the motor being stalled would still use the same amount of electricity, so is it just a cheap design?
>>
>>900769
OK anon, this kind of shit is complicated to explain because for starters, you are not saying what you want to do with the MOSFET. MOSFETS and BJTs have 2 modes of operation each.

If you are trying to just toy with it, use it as a switch, it says on the datasheet that the MOSFET has very low RDS when on, which is pretty much saying that the MOSFET is designed to be used as a switch.

Just saying "i want to MOSFET" is not enough. Try again faggot.
>>
>>907744
>So is the coating of the windings of the motor are just able to handle any heat that the 6v could generate.

right, a 6V motor should be able to handle 6V power indefinitely, as long as it's spinning freely.

>I guess the motor being stalled would still use the same amount of electricity,

this is not correct. when it's stalled, it will take maybe 2x to 10x as much current. that's coz, when it's spinning, it acts as a generator, which opposes the battery voltage, and reduces current. if you apply too much load, it goes slower, which makes the generator generate less opposing voltage, so the current from the battery increases, and the motor gets hot.
>>
>>907763
Neat, so how does their method differ from a servo? I'm pretty sure servos use potentiometers to tell what angle the arm is at?
>>
>>907768

a servo is a completely different animal from a DC motor. a DC motor has 2 wires, you apply voltage and it turns one way or another depending on polarity. a servo has 3 wires, where the third wire receives a pulse telling it what angle it should be at. a 1msec pulse means furthest CCW position, and 2ms means furthest clockwise position, with other values in between. to do this, it incorporates a chip for control, and a pot to measure angle.
>>
I'm trying to control 3 10W LEDs with the arduino PWM output through a MOSFET, an IRLB3034PBF. It's working fine for the most, but when I start dimming it, at lower levels (under 75/255) the light starts visibly flickering. The arduino logic output is 4.8V, so is it that the MOSFET doesn't open properly because of the low voltage, or is there something else I'm overlooking?
>>
>>905341
It's a typo, you won't find raisin-core solder unless it's from china. The Chinese tend to misspell English words. This happens a lot when you order stuff from ebay for example.
>>
>>907787
You need to up your switching frequency. When you go to lower duty cycles, flicker becomes much more apparent. If you think about it, there's a lot more off time per cycle for your eye to detect the LED turning off. I've had this problem too.
https://www.arduino.cc/en/Tutorial/SecretsOfArduinoPWM
>>
>>905341
You can get rosin-core solder from places like RadioShack, Harbor Freight Tools, or Ace Hardware. These are just a few places that you could actually walk in and buy solder, there are plenty more! If you need a soldering iron they probably have that too.
>>
>>907791
http://playground.arduino.cc/Main/TimerPWMCheatsheet
>>
>>907788
>>907792
Whoosh.
>>
>>904463

Whoa. Where did you find this? It looks quite damaged, but from that LF355 at the bottom it doesn't look like it was made in USSR...
>>
>>907792
>>907788
Not sure if autistic.
>>
>>907791
>>907793
Thanks, although in the end my problem was from the fader code I wrote, which was wrong. But it looks better with higher frequency PWM either way.
>>
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What are the symbols with four triangles that are connected to the Y... pins? How could I simulate this component (CD4053) in Logisim?
>>
>>907912
More like two overlapping triangles.
They're transmission gates, which is a fancy name for a combination of one N and one P mosfet. It's a switch. When turned on, the resistance between the left and the right side is (relatively) low and it can be used to pass analog signals both ways.

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

>How could I simulate this component (CD4053) in Logisim?
If Logisim is so shitty that it there are no analog switches (that 4053 or 4066 or whatever), you should consider using a less bad simulator.
>>
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I want to make a clock :D

Would this setup work?

#1 Microcontroller (firstly I would use an Arduino AT328, then possibly Atmel8 on a protoboard)
#2 shift register, and it would multiplex to
#3 4 different 7segment LEDs (knightbright SA39-11)
#4 via the NPN transistors.

uC would sent the appropriate number to the shift register, turn on the transistor and it would light up. The shift register would sink the current from the 7 segment, without any resistors.

As for timekeeping, I would use a chinese DS323 knockoff (2$ from ebay) via I2C or try to use the internal xtal reference.

Would this work, do you see any obvious flaws from an electrical standpoint? Code shouldn't be too much of a problem.
>>
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here's how it would look like on a protoboard.
>>
>>907925
Jesus christ.
>>
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>>907925
>>
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>>907922
Thanks for your help, man. I just never saw that symbol before.

I made it into a Logisim sub-circuit that I can insert into other circuits.
http://pastebin.com/1qYThBaX
>>
hi /ohm/

i've got an integrated h-bridge (TLE 5205-2) running a 12v brushed dc motor off of a pwm signal created by an arduino. the motor works fine at ~98% duty cycle, but for some reason when i provide a 100% duty cycle/5v digital output to the bridge, the motor doesn't start. it just makes a soft click and rests idle.

i don't believe it's stalling because it doesn't whine, and i don't believe it's a current issue because the motor draws 1.6a idle and everything supplying it is 5a rated. this occurs at any pwm frequency from ~120-4000hz.

does anyone have any idea as to why this may be happening? google offers nothing. the motor works satisfactorily with 98% pwm though so i'm not concerned, just curious.
>>
>>908006
where are you supplying pwm signal?
which pin?
>>
>>908014
sending 5v to in1 (3) and PWM to in2 (5), or vice versa for the opposite direction
>>
>>908016
oh yeah i mistyped some stuff, by "full duty cycle" i actually mean 0% pwm to provide a straight high in1/low in2. i confused myself because of the way i wrote my code.
>>
>>908016
yeah so if its 100% pwm both inputs are high so outputs are ZZ.
whats the question again?

keep 1 low and pwm 2 or pwm them both dependidng on direction. boy thats stupid.
>>
>>908019
>high in1/low in2
gives 'break'output
so don't expect it to go anywhere
>>
>>908020
i believe the bridge datasheet suggests that you keep one input high and provide the pwm signal on the other input. i don't know the distinction between that and your suggestions as i'm not an EE student, but that's why i chose that method.
>>
>>908026
you sure you're reading the datasheet correctly? H/L drives the motor according to the table i'm looking at
>>
>>900769
"VGSth" is the voltage at which the MOS is fully ON, it says 2,35V max so apply 2.35V or more on the gate and your MOS is happy
>>
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>>906952
>>906957

if audio engineers werent fucking retards, they'd design their amplifiers for ~3x the average power of normal audio tracks.

however we live in a world where the audio standards and best practices are obfuscated and the only real resource is one guy's hobby website.

if every audio engineer was to design their amplifiers for ~3x their marked rating, stereos would be able to handle those dynamic highs and lows that are compressed in current audio media

unfortunately this means that if you want a 100W amplifier, you need to design it for 300W, which is a gigantic price difference with discrete components
>>
>>903481
>>903414 is wright, fft just takes more time to process
>>
>>908044
No it isn't. It's the voltage where the mosfet is slightly on. Definitions for "slightly" vary, but Id = 100µA is a typical value.
You better check the test conditions for RDS(on) to get an idea what the manufacturer thinks you need to turn the fet "fully" on.
>>
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Could someone provide a good resource about underatanding the programming on PICs, so far I'm having lots of trouble adapting to the logic used, I can program in C but there's lots of work arounds used in microcontrollers that I simply don't fully understand.
>>
>>908081
Microchip should have architecture manuals for all their chip models. The most important details regarding 8-bit PICs are banked memory, and a fixed depth call stack. It's a very C-hostile architecture that will impose limits that modern architectures (eg. AVR) do not.
>>
>>908081
Without knowing what compiler and family you're using it's hard to give any advice. Is it MCC18? That requires you to declare all variables at the start of a function like in Pascal. Any algorithm you've written in a different C compiler should work after you've fixed that. Avoid floating point math as much as possible, that's really slow on a microcontroller without a floating point CPU.
>>
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>TFW spending 12+ hours in a row hacking a circuit >TFW shoving all your autistically identical, cross compatible boards into one of their backplanes
>TFW turning it on and watching it work perfectly on the first go
>TFW you weren't even nervous because you knew exactly what you were doing the entire time

Here's a picture of the 44 A variable voltage switchmode power supply that I just spent an entire day putting together.
>>
>>908253

I want to know everything there is to know about this.
>>
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>>908257
I have two of these units (plus parts for 3-5, but no backplanes), plus full documentation and schematics. They used to sit at a 30 kV potential inside a TV transmitter (hence the giant isolation transformer), providing the focus voltage for the giant transmitter tube. I've slowly been converting them into lab power supplies, and today I redid the cooling system to use normal computer fans rather than screaming ball bearing 24 V industrial fans, as well as adding meters to one of them.
>>
>>908267

What is this used for?
>>
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>>908267
>>908270

I just use them as general purpose high current/low voltage lab supplies and battery chargers.

They're built around pairs of INSANELY expensive Ericsson power bricks, and their output impedance is just ridiculously low, something like 1 mOhm before the meter current shunt, and something like 25 mOhm out of the front panel. You can basically power anything that doesn't use more than 44 A peak off of them. If often load test UPSes and inverters straight off of their output. Since they soft current limit and don't mind short circuiting, you can also use them to see how cables and contacts behave under heavy load.

They were originally controlled by these proprietary optical interface cards, and I've reverse engineered them to be manually controllable. Their voltage range is about 1-15 V, and they soft current limit at 44 A. The isolation transformer starts to go up in smoke at more than about 300-400 W continuous output, though.
>>
>>908275

How did you obtain these power bricks? I would love to have some extremely high current power supplies but don't know what kind of curveball I would have thrown at me if I tried to design one myself.
>>
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Stupid question:
I'm looking for the component used in pic related as a micro SD card slot.
Been looking everywhere, can't find shit.
Tried looking up the odroid w parts list but I can't find anything.
Help would be greatly appreciated.
>>
>>901386
Epoxy might be thermal arildite for heat transfer.
>>
>>908289
I got these through work; I work at a transmitter site some times, and we were tearing down old gear to make room for the new. It's difficult to say where you'd get your hands on something similar, low voltage/high current supplies are kind of unusual to find. Especially since you basically need them to be SMPS in order for them not to cause screaming hellfires.
>>
Is electricity magic?
>>
>>908300
You'll probably find something you like here: http://www.digikey.com/product-search/en?keywords=microsd%20socket
>>
>>908360

Any good references on smps design?
>>
>>908464
Found it, thank you so much smartyAnon
>>
>>908081

sorry m8 I only program PICs in assembly but I'd be happy to help with that if you're just doing something project specific
>>
Is precise location control the only benefit of using servos over motors?
>>
>>908508
Sorry, I'm definitely no expert on the topic, so what I know mostly comes out of datasheets.
>>
So I want to power two or three computer fans externally (i.e. without using a computer and/or PSU), I want to also be about to easily control their speeds, so how would I go about building a small pwm circuit from scratch to control the fans? Or should I just hook variable resistors in series with the fans (one resistor per fan) and write them all in parallel?
>>
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Stupid shit here yada yada.
Got a nigger-rigged solar setup, panels through a charger to a set of 12V car batteries.
It's at the school I work at, I wanna be able to charge a shitload of 2A USB devices off it.
12v DC to 5v DC step down is the obvious, but I'm a little worried.
The batteries sway from between 8 and 14V, I want an apple-tier regulated 5v solid.
Then I wanna split that to some USB ports, perhaps 20 or so, and limit each of them to 2A.
Just worried a student might plug in some shit chinkphone and a dodgy solder job pulls 20 amps into his hand.

In short, need a (Preferable /diy/ for fun) 8-14V stepdown that always puts out a smooth 5V.
If someone gave me the basic parts I'd be able to make a PCB in eagle and order it.

Just curious how to keep the power smooth?
20 capacitors of various capacitance on the input? Output?
>>
>>908881
Fuck, found this:
ebay.com/itm/DC-DC-Converter-Step-Down-Module-12V-24V-to-5V-10A-50W-/140795453634
Any way for an idiot to check how clean it is?
School's got some oscilloscopes, but I've never touched the things.
Also anything I can do to make it cleaner?
Cap on the input/output?
>>
So I am building a circuit which has a 16x2 LCD display hooked up to an arduino. The display has a 25 Kohm potentiometer hooked up to adjust the brightness of the letters. I want to replace this with a singular resistor but don't know what value. I tried using the arduino to map out what the resistance output is, but this is my first time with potentiometers, so does it go from 0-25k or some other number?
>>
is it possible to build a binary clock with a 555 timer and a 595 shift register? I don't think something this simple requires a microcontroller
>>
>>909111
You can, but the problem with 555 timers is they aren't perfect. After a while your clock will be off and you'll have to reset the time. That's generally why crystal clocks are used instead with microcontrollers. If you want to keep it simplistic look into getting an ATTINY85V. They can be programmed with an arduino development board if you have one on hand.
>>
>>909203
I have an attiny85 chip and a crystal, but I couldn't find anyone or any guidelines for creating it with a 555 timer and a 595. I guess you'd have to make a binary counter, but how do you do that with a shift register? What would the DATA in be in this scenario?
>>
This should work as a charge pump right? If i just feed alternating pulses where the two switches are? What have i done wrong?
>>
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I made a thread a few weeks ago about a broken power supply. I've finally got hold of a multimeter and attempted to fix it.

I think I've found some fault - not long before the output terminals (that show 0v) there's a big-ass capacitor (3300uF). I get a voltage across that (17v) but just down stream there's a large resistor that now appears to be a complete short circuit.

This multimeter has a mode where it beeps when it encounters a short circuit. Every resistor except this one doesn't make it beep.

I don't get a voltage drop either.

Also, the fault of the PSU is that it always has the red LED on (indicating a short), so it seems to make sense.

But can resistors fail in this way? I mean making a near-zero impedance short circuit?

PS: I damaged the PSU by accidentally feeding a 12v battery into the inputs. It drew a fuckton of current, melting wire sheathes and burning me, now it doesn't give any output.
>>
Test.
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