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
>>909883
I have a question.
I want to connect a single 3.5 wire from the computer and have it split into speakers and headphones. I want to have two switches connected to the ground of each (Headphones/Speakers) so that I can choose which one gets any sound. Would that work?
Will the headphones stay silent with R and L connected but GND being opened at the switch? I can whip up a diagram if the description above is confusing.
>>910040
> Will the headphones stay silent with R and L connected but GND being opened at the switch?
No. You need to use a double-pole switch to switch both the R and L wires.
Also, you really should be connecting speakers and headphones to different jacks. Active speakers (powered, with a built-in amplifier) should be connected to the line-out jack, headphones to a headphone jack.
A headphone jack may have too high a voltage for something expecting a line-level signal, which will cause distortion. The line-out jack has too low a voltage and can't source enough current to drive headphones or speakers directly.
>>910048
Ok, I will look into double-pole switches.
The reason I'm doing this is because at the moment I change between headphones and speakers (Amp with speakers attached to them) by changing what is plugged into the Audio/USB extension that used to be in the front panel.
Works fine for me, but I would rather reduce the number of lose cables and switch between the two with a flick.
I have been wanting to get into electronics too. A few days ago I bought the book in the picture. I decided to go to radio shack to pick up the parts for the first chapter and I saw these 2 kits that went with the book I had bought. They were on clearance for about $55 each. Did I do good or am I boned?
>>910055
Probs got a little ripped off yeah but it's only $110 total. I don't know what's all in them but the important part is that you have a place to start and the materials to do so, so whatever go nuts.
Welcome to the fun
I just got a daft punk helmet. It's the bare cast. I have minimal knowledge on small voltage DC electronics. Where do I get started on programming led arrays? Is an arduino the best option for this task? Is there a smaller arduino that would be a better suit?
What are some reputable electronics parts sites?
Thanks
I'm building a tracked robot controlled by an Arduino and I want to read the the on-board motor battery voltage. Would an octocoupler be a good idea for this or am I barking up the wrong tree?
>>910060
>little
that's a massive understatement, but the price you pay for impulse purchasing things.
Now make the best of it and get reading. Look ahead in the book and if there is something that tickles your fancy either start there or work your way up to it keeping that project in mind.
>>910196
depends on what voltage your battery runs. if it's under 5V (i think) it can use the ADC and return a value.
>>910206
It's 12v. I'm sure shoving 12v into an Uno is a bad idea
>>910207
Use a voltage divider to bring the 12v battery voltage down to 5v for the ADC. For extra protection add a 5v zener to ground.
I got these switches but can't seem to find a data sheet for it. Any idea what I plug into what pin? I am trying to connect it to an RGB led.
http://www.ebay.com/itm/10-pcs-SS-24E04-PCB-10-Pin-4-Position-2P4T-DP4T-Mini-Vertical-Slide-Switch-/161806036725?_trksid=p2141725.m3641.l6368
>>910211
>2P4T
2 pole, 4 throw.
there will be two main contacts (poles), and four possible connections for each (throws) (A0,A1,A2, A3~B0, B1, B2, B3). 10 pins in total.
worst case use a multimeter and check it for continuity on all positions in case I missed something.
>>910211
I found what appears to be what you were looking for. If you just look up
SS-24E04 (part number)
one of the first results is:
http://www.hldz.com.cn/en/product_show.asp?id=373
where the pinout is labeled "circuit"
To read more about poles:
https://en.wikipedia.org/wiki/Poles
https://learn.sparkfun.com/tutorials/switch-basics/poles-and-throws-open-and-closed
>>910210
Voltage dividers to ADCs can be made with large resistor values, so trying to "save power" by switching them off and on is always unnecessary.
If the voltage divider is made with a 100kΩ and 240kΩ resistor the current it's sucking out of the 12v battery is 12v / (340kΩ) = 35µA
Trying to switch this off an on means CPU cycles for the logic and current to drive the MOSFET which will cost much more than it saves.
Spent the past week cramming for exams (tfmosfet you use kn in place of 1/2 kn), cut 200 mA of current from my portable project, will give me 2 more hours of battery life.
Switching power supplies 4lyfe.
I want to switch 3Vdc 1A with a BD139. Will a base resistor of 220Ohm on a 5V TTL output be fine?
Datasheet:
https://www.fairchildsemi.com/datasheets/BD/BD135.pdf
>>910329
Not really. The guaranteed minimum hfe is just 25 and even if you went with the typical value of around 50 @ 1A, you'd need to overdrive the transistor with several times higher base current to get it in decent saturation. Rule of thumb is 5 to 10 times overdrive, so you'd need 0.1 - 0.2A of base current.
A logic level mosfet would be much easier to drive.
I've been planning a microcomputer system based off a 6809 for some time now and looking online at the memory maps that result from address decoding, they all place ROM at the end and RAM at the beginning of memory.
Why is this? Dont you need rom for the first few instructions?
>>910351
6809 and several other old processors either fetch the starting address from or directly jump to memory top. Thus, ROM will be at top.
I am experimenting with a basic circuit of a 5mm 940nm wavelength IR led and the corresponding 5mm photo resistor, I have to have the facing each other perfectly and really close. But I just got to play around with a grad students laser tag system project where it is using IR leds and recievers but has a circle of effect of like an inch in diameter and a range of over 100 feet. Is there something I should be doing to improve my circuit or are there better IR emitters and detectors?
So if I had a homemade emp generator made from a disposable camera, would I need more power to extend the radius? If that's the case would I need a circuit board that can withstand more voltage? Sorry if it's dumb questions, new to this.
>>910351
the 6809 jumps to the address contained in $FFFE- $FFFF on start-up, so the ROM has to be at the top. just below that you have vectors for the various interrupts, and they need to be in ROM as well. usually RAM is at $0000 and the various vectors at the top of RAM point to locations near $0000 so that they can be altered (being in RAM).
>>910371
Like I said, I'm new to electronics. I'm just trying to figure out what use in order to create like a 10 ft radius
>>910375
Why do they have to be in ROM?
Does it not start with interrupts disabled?
>>910387
because when you turn on power, there's random stuff in RAM, so it has to be initialized (program loaded) before you can jump into it.
i just realized that having the reset vector point directly into RAM is silly, for the above reason, so it's a little more complicated to change the vectors. one way is to have the reset routine in ROM check that a sentinel (a particular byte sequence) has been set in RAM to tell it that the RAM was initialized, and therefore the reset routine can safely jump into the reset vector in RAM.
as for the interrupts, i think they're disabled, but RESET cannot be disabled. if i remember, neither can the NMI, but i'm not sure.
>>910371
Does it matter if I choose photodiode or photo transistor? Or are the relatively the same in their strengths and just act like their respective base components?
>>910392
There are processors which allow you to move the interrupt vector table or which have it at low memory to begin with, but if the reset vector is at memory top, you're bound to have some ROM there (or at least some ROM-like shitty kludge). And if you have some ROM there, it's usually the easiest option to have it all there.
>>910396
A phototransistor is more or less an equivalent of a photodiode followed by a transistor. It gives much higher output current than a photodiode, so you get better range without any additional amplifiers.
>>910396
photo-transistors are usually preferred to photo-diodes coz the diodes create a considerably lower signal voltage, meaning you need more amplification.
>>910375
So will I have to program those vectors into my ROM?
When I did static testing with the 6809 with the data lines tied to NOP it never went to those addresses, it always started at 0000
>>910414
Yeah. Is there some actual reason why you can't connect and program it the way it is supposed to?
>>910414
static testing? i'm pretty sure the 6809 has a minimum frequency of 100khz. maybe you have an Hitachi 6309, which is 100% compatible, but has a bunch of extra stuff.
anyway, a 6809 will definitely fetch an address from the last 2 memory bytes and jump to that address, not $0000.
>>910392
Some old systems were designed so the ROM could be switched out and replaced with RAM, so the vectors could be changed. It's also simple to have the fixed vector handler jump via a RAM vector, which is initialized by the boot ROM.
Is there a place I can order custom milled breadboard? I have been googling a bunch and can only find software to design the breadboards and make the G-Code for it but I don't have a mill yet. Anyone know a place I can send the design and have the result shipped to me?
>>910090
If you want to be done quickly then yes the arduino is the best choice. There are many tiny avr boards like the arduino nano. If you have tons of LEDs use shift registers.
>>910227
Coming in late on this, but for slide switches, the two rows of pins are each their own contact. Most slide switches have all the pins effectively isolated, at leas in my experience. The actual sliding thing simply makes a 'bridge' across the two opposite sides. Hopefully the graphic makes better sense out of this.
So how do you make a slide switch 1 pole X throw? Solder one whole side together. Slide switches are actually marvelous alternatives to rotary switches, and I'm sad to see not many people using them.
Has anyone done any work on video game related stuff...like fighting game joysticks?
>>910665
foreplay is not allowed on /diy/ - just ask your question straight up, ma nigger.
>>910226
But the voltage is 8.47.
What are some decent methods of reading the RPM of a drill?
I'm having some wild fantasies of making a PID regulation capable PWM controller.
Technically speaking I might be able to get the info I need by measuring the voltage drop on load, but I'd also like to display the RPM on a few segment displays, meaning that calculating it from it the voltage likely wont produce a good enough result.
I do have some IR sensors laying around, but I'd like to keep the mechanical aspect of the construction as small as possible.
>>910761
if you have a oscilloscope, put a neodymium magnet on the spinning part and an inductor in a fixed position next to it
it will generate a sine wave through the inductor you can read with your oscilloscope
>>910774
I did think of doing that since I saw AvE do it in a video.
I think it might not be the best idea though. There's the factor of the magnet flying off. I mean, I could put more stuff on to hold it in place, but that would make using the drill a bit harder, since changing bits requires me to take off the rotating part.
Besides the obvious danger factor, the magnet would likely fuck with the balance of the rotating shaft which can't be good.
>>910779
http://www.amazon.com/AGPtek%C2%AE-Professional-Digital-Tachometer-Contact/dp/B004Q8L894/ref=sr_1_2?ie=UTF8&qid=1449333642&sr=8-2&keywords=tachometer
![DSC_0591[1].jpg](https://i.imgur.com/Cdqu3X4.jpg "DSC_0591[1].jpg")
Hello /ohm/, I've been trying to repair an old monitor. I've replaced all faulty caps but it's still not working. There's a certain chip that at some point heated up so much it melted the insulating piece of plastic and I think that's IT'S the reason it's broken. When you turn it on, you can only hear a high-pitched sound, no backlight nor image. Is it fucked?
![DSC_0593[1].jpg](https://i.imgur.com/LVM0V8C.jpg "DSC_0593[1].jpg")
>>910811
Power board in question, the chip is about under the black mark on the bottom.
>>910779
>There's the factor of the magnet flying off.
They are some pretty strong-ass magnets. For extra peace of mind why not just duct tape it.
I'm coiling and I need 200 spins, the area won't suffice and I don't know if I can keep coiling on top of it.
>>910815
you can double-wrap coils over transformers. If you crack open commercial transformers there's usually several layers of wire wrapped around the core / bobbin.
>>910821
Thanks m9
Does anything like this exist? Preferably asynchronous.
If it doesn't, what's the simplest way to make it?
>>910843
It's called dual port memory. There's several chips you can buy, and almost every old VGA graphic card will have one you can salvage.
>>910844
Thanks m8, do you know if there are any with simultaneous read and write access for each port?
>>910848
All dual port memory chips allow simultaneous reads and writes on both ports as far as I'm aware. Two ports would be pretty useless without that. The only restriction is you can't read/write the same byte from both ports at the same time.
This is a project I used a CY7C136-25JXC for. One microcontroller writes video data to it and a second microcontroller handles reading it and generating the video signal. I can dig up the project report if you're interested.
https://www.youtube.com/watch?v=OMP28JZBSlo
Is there a modern software circuit simulator with a decent UI that I can pirate? I don't like this web based stuff.
>>910862
Not quite what I meant.
>>910848
>simultaneous read and write access for each port
>simultaneous
>for each port
I.e. read from, and write to, a single address at the same time using a single port.
But then I realized I could just read directly from the data source instead.
>https://www.youtube.com/watch?v=OMP28JZBSlo
Damn, that's cool. I wasn't planning on making anything anywhere near that advanced, just a simple digital synthesizer sequencer where it's possible to edit a step independent of the running sequence.
>>910864
They used to be included in the OP, dunno where that went.
Anyways, I use Mouser Multisim Blue. It's free.
I posted here before.
I've got a Mixamp by Astro gaming. Problem is that I'm a fucktard and was a bit too aggressive with it, resulting in damaged pads. Its the data - and data + pads that are removed from the board. It's a shame it isnt power or ground where I'd be able to easily jump it onto a visible trace.
Where could I hook the data + and data - to? Or how can i find where without a multimeter?
>>910870
Find datasheets on the ICs on the board. One of them should have a USB transceiver with d+/d- pins.
>>910870
>Problem is that I'm a fucktard
No argument here. Scrape off the solder resist and solder short jumper wires directly to the traces. You really don't want long, noisy air wires for USB data lines.
>>910877
I can't seem to see with my own eye what traces are for what. Doesn't help that there is no schematic out there either.
>>910870
Hi Ken...have you converted from Nikon to Canon yet?
>>910868
Looks good. Thanks.
Looking for a new soldering station. Ideally something with hot air, digital and soldering iron. Ideally would like it to have the ability to use hot tweezers and for it to be a pretty cheap unit.
>>910882
Didn't even realise that was there.
Fancy paypalling me $20? I've got to feed my kids.
>>910052
Any modern audio driver should automatically switch to back audio when front audio is unplugged.
>>910055
Is it a kit for every project in the book? Or 2 separate projects? Whats in the kits?
Quick question, what is the device that gives a gradual increase in power to something, for example the knob you turn on a rotary tool for speed, whats it called?
>>911165
Rheostat/Potentiometer/Variable Resistor
>>910879
these are obviously the traces you want.
you can make a continuity tester with a 3V button cell and a white LED.
>>910761
Meh, I wont be making it.
Just went with simple PWM on a breadboard and tried to drill a PCB with it.
The little drill just doesn't have enough power at anything other than 100% Duty cycle
Hey /diy/
I want to make a seebeck generator to charge my phone and kindle while /out/ camping. I'm fairly new to electronics and am still learning so I have a few questions.
http://customthermoelectric.com/powergen.html
I've been looking at the above website and trying to figure out what parts to get. Let's say for argument sake I'm trying to charge a battery over USB. (5volts) I'm pretty sure if the seebeck is producing less than 5V it' won't charge at all. So I need to get a really powerful module or use more than 1. But what if I have too many volts? It'll fry my battery, right? Would a simple voltage regulator be a good fix for this problem? Also, what about amperage. I suppose too few amps it'll just charge very very slow but what can happen if I have too much amperage when charging batteries?
>>911243
At least you got a chance to get your name out there again though, right tripcunt?
>>911267
> a seebeck generator to charge my phone
so you gotta start a fire every time you wanna charge your phone? sounds silly. you're better off with solar cells attached to your backpack. if you can wire enough cells in series to give you 10-24V then you can use something like a Blackberry car charger, coz it's rated for 10-24Vdc, and puts out 5V that you can use to charge a LiPo pack with USB input (to charge the battery) and USB output (to charge your phone).
as a backup, you can carry a hand-crank generator, also with USB output, since this is the new standard for almost everything chargeable.
>>910864
There's a suit called Proteus
All tutorials are made by poo in the loos though
>>911290
>>911290
a thin sheet of metal, measuring 2inches by 2inches, weighing less than 2 ounces, that can produce 20watts of electricity any time you want.
VS
a fragile piece of glass, 2 feet by 2 feet wide, weighing 6 pounds, that only works in direct sunlight on very sunny days.
>so you gotta start a fire every time you wanna charge your phone?
If your camping you're going to have a fire. If you got a small gas stove it might be be several times a day to heat water and cook meals. Ideally you have the seebeck charging an external battery at meal time and use that battery charge any devices that need power during the day. Or that's the plan anyway. If I can get the power regulated well enough that I won't fear destroying my devices I'll just charge my phone directly from the seebeck. Again, I'm worried about the over amperage.
>>911290
Not that poster, but I think the idea with the thermoelectric chargers is that you're generating all that extra heat when you're cooking anyway, might as well capture it.
Plus, with a stove such as the billet, the electricity generated also runs a small fan that improves combustion.
Of course it's not going to generate a ton of power or anything, but it's a nifty concept imo.
>>911392
I forgot to mention I'll probably stick my seebeck under my mug when boiling water kinda like pic which is a commercial version of what I'm trying to do.
Like >>911394 said. Not creating fire JUST to charge stuff. Will already have a fire going, just giving the fire an extra use.
>>911392
>a thin sheet of metal, measuring 2inches by 2inches, weighing less than 2 ounces
You need to generate a temperature difference across the generator. Meaning that you need a largish heatsink on the cold side. Also, those things you linked are made of ceramic and semiconductor pellets. They aren't as rugged as you think.
To answer your original question... The output voltage is proportional to temperature difference, so you can expect it to fluctuate quite a lot. So, either design the generator for significantly higher voltage than 5V and use a step down switcher to produce the charging voltage or use a switcher which can use voltages above and below the output voltage.
>>911392
> 20watts of electricity any time you want.
20W assuming you bought the most expensive device, and are using it under ideal conditions, presumably with a large water-cooled heat sink, requiring running water.
and you gotta baby-sit the thing to make sure you dont go over the max temp and destroy the device, which just happens to be 300-deg C, the temp at which wood just starts to burn.
>>910565
Actually, I want to know this as well. I am not the best at soldering across channels on regular boards so if I could have custom milled boards sent to me, I would be more than willing to pay any amount.
help me understand /ohm/... i dont understand the concept of a device drawing current vs the source just sending all of its power at once.
how come, say, you stick a fork or wire in socket and you trip the breaker and fuck shit up but if you hook up something like a microwave transformer (that is just 100 or so turns of copper wire) everything works just fine? its more or less the same shit just with more resistance right?
or how like an electronic device can have a couple batteries in it that can max out at 5 amps output or so, but only send the current the device asks for instead of just frying it.
i just cant wrap my noodle around how this works.
>>911455
look up the water pipe analogy: the water pressure is voltage, the diameter of the pipe is the resistance, and so the water flow (current) is a function of those other two items. more flow if the pressure is higher, or the pipe wider; less if lower pressure, or pipe is thinner.
>>911455
>its more or less the same shit just with more resistance right?
There's this thing called inductance which is the reason an unloaded transformer draws only little current.
https://en.wikipedia.org/wiki/Inductance
And it's not like your fork will draw infinite current. If everything in the circuit (the fork itself, wiring, fuses, pole pig, etc.) could handle the resulting current and wouldn't limit it in any way, the fork would also draw "only what it needs" and no more. The resulting current would be thousands of amps, though, so you trip the breakers before everything catches fire.
>>911455
Plumbing analogy is pretty useful here. Voltage is the difference in water pressure between two points. Current is how much water is flowing between two points. Resistance is the diameter of the pipe. A milk jug with a pin hole isn't going to empty all at once.
> a microwave transformer ... more or less the same shit just with more resistance right?
No it's more complicated than that. The transformer coil is an inductor. When current goes through an inductor it builds up a magnetic field that wants to push electrons back in the opposite direction. This field eventually reaches the same voltage as the current, so now no current can travel through the inductor.
Anyone here work with RFID/NFC tags?
I need a standalone NFC reader and writer, because I want to crack the NFC tags used by the DaVinci Jr 3D Printer so we can use whatever filament we want.
Problem is, everything on the market seems to be made for generic "throw your phone at this tag to do this thing" crap, whereas I need an NFC reader and writer that can modify the entire chip regardless of what format it's using.
My phone, an example of one of these, only operates on NDEF-formatted NFC tags.
>>911445
I don't remember the name of it, but there's a type of board where the pads are shaped like a clover, allowing easy bridging in all four directions. There's also double-sided boards with channels down and across on opposite sides. If you can't find them, they're easy to design and have manufactured in one of the cheap Chinese board fabs.
Hello friends.
I'm trying to test some caps in this monitor with lines all over it.
I'm adding some capacitance to the circuit to root out any bad caps.
(I'm also getting some whining noises on the power board which I think - Read:hope - are unrelated).
Anyway. My question is:
How do I safely add capacitance without killing myself or ending up in A&E.
At the moment I've got a 470uF, 50V cap on a bread board with some jumpers.
I apply the jumpers to the capacitor I'm checking, then I discharge through the 1M resistor after each one.
I'm getting one or two sparks, and that freaks me the fuck out. should I wear some thick leather gloves too?
TL;DR : Capacitor testing safety.
>>911807
the capacitor needs to be rated for the circuit it is in
do you know it wont exceed 50v?
50v is almost safe if you know thats all there is on the circuit and you arent retarded
if you are a pussy then give up
In the pastebin, what's the most beginner friendly youtube channel? There's like 13
>>911817
All the caps in the circuit are rated for 50V or less.....all apart from that big fucker which is 450V which I'd rather avoid.
>>911817
>if you are a pussy then give up
Also....I'm not a pussy. I'd just like to you know... not die from being a retard.
Hey diy,
Cord died near jack on yet another pair of headphones. Again.
This shit is getting way too old.
Anyway, I've got a replacement 3.5mm jack for 0.5$ and soldered it on.
Headphones kind-of-work, left and right channels are fine, but it feels like one of them is slightly louder now.
The question is, I guess — is there more to it than just soldering the right wire to the right part of the jack?
>>911866
your solder looks shit, the oxidation adds resistance, hence the loudness
get good at solder
Hey, I am trying to design some files in eagle to later machine them, but one of my parts is a switch I can't find an eagle file for anywhere. So I am making it myself, my question is what is the average distance between pins on the average solderless breadboard? Because the switch is meant for those but I dont know what the distance or hole diameter should be and I cannot find the measurements online.
>>911867
>your solder looks shit, the oxidation adds resistance, hence the loudness
Can you put it in more measurable terms? I need to keep soldering until I get equal resistance on both channels as measured by normal multi-meter?
Does this looks like a 1:1 transformer to you? Could I use it as an isolation transformer for my digital scope?
I took it out of a telephone rack PSU
>>911875
Don't add more solder. take everything off, clean it all well and try again. If you have a choice, use a large tip, the jack has a lot of mass to heat up.
If you don't have a large tip let the iron get nice and hot and let it got nice and hot between spots.
It needs to heat it up quickly. If you just let it sit on there and heat up slowly it'll oxidize and melt plastic and look like shit.
>>911877
It looks like a ferrite core transformer. Those aren't for 50/60Hz.
>>911866
See those holes?
Poke the wires through them, then solder.
>>911878
I know how to improve soldering ingenreal, thanks.
The question is — what should be my end-goal?
"Soldering should look good" does not sound like the only requirement.
>>911885
solder should look good because that is the only way it will work properly
that should be your end goal in term of soldering
that is the only and the one indication of your soldering skill and of the quality of the joint
so yes that is all you need, basically
if you are butt hurt, look at nasa soldering standards and other similar standards
>>911879
The core is metallic, that's just my shitty camera making it appear black. Also the traces on the PCB it was on seem to indicate it was connected to the mains.
>>911893
"looks good" is not measurable.
Resistance, on the other hand, is.
So, I will repeat my question: keep soldering until I get equal resistance (measured by normal multi-meter in DC mode) on both channels? Or is it some other measurable parameter should be looking at?
>>911900
1/10 for making us reply, you got me
>>911910
Are you for real? I'm asking to give me some measurable parameters to monitor instead of "solder looks good" — and you get offended?
>>911900
Newbie here.
Even I can see your solder skills are wack.
Redo the entire thing. Trim back the cable, push some heat shrink round it first, strip the insulation, twist the strands and tin the end.
Then Solder it, and shrink it.
It's obvious that joints should be cleaner than what you have there mate.
P.S. Don't use the wire insulation as flux ya dummy.
>>911894
That my friend is a RF choke, both windings are the same amount of turns, but are wound in opposite ways.
>>911894
it looks a lot like a double choke used to keep electrical noise from the power supply from going back into the 120V line. it doesnt look like the two coils are coupled to each other through the core, which means it would suck as a transformer.
if you have an old 56K modem card you can almost certainly pull out a 600-ohm isolation transformer with a 1:1 ratio.
>>911919
You seem to be under impression that I somehow argue with the re-soldering idea or that I don't understand what you mean by "better soldering".
Neither of that is the case.
However, I want to understand what _measurable parameter_ I'm trying to fix by better soldering, and what my goal on that measurable parameters is.
We kind of figured out it's resistance I'm look at, ok.
So I'm trying to clarify if it's just normal DC resistance (measurable with multimeter) and if it's having resistance equal on both channels is what I am trying to accomplish.
>>909883
Anyone else using ALTIUM here?
I feel like I'm the only one in the world...
>>911951
to clarify, there is no measurable parameters in a solder joint other than oxidation being not acceptable, it is not a measurable thing, it is a yes or no thing, your joint either works as intended, or not, or you will introduce problems, it can be a crack, a short, poor conductivity, poor durability, etc, which should be zero if you have done a normal solder joint, which you obviously cannot
if you want to know something that is measurable, that is your solder is bad and is not acceptable, on a scale of 1 to 10 you get zero because it is not a proper solder
>>911900
Actually 'looks good' is the best way for a DIYer to assess a joint.
I said you need a bigger tip too because you're clearly leaving it on too long, the whole thing is getting hot and you're melting the rubber/plastic nearby. If this gets too bad the insulation down the wire could be damaged and causing a cross/short. (Particularly with headphone wire where the insulation is so thin)
https://www.youtube.com/watch?v=vIT4ra6Mo0s
This is a long series but it's good watching
When you're done with that, this guy is good too.
https://www.youtube.com/watch?v=0SnOW2VdCTI
>>911969
>tfw you solder daily as part of your job for 15ys and you still cant identify a 'cold' joint.
you guys are just fucking with me right?
i can see 2 is a little more shiny but i couldn't pick it out on its own. 1 is the same as all the others.
How do quadcopters manage to control 4 bldcs in such a small space? From what I've read individual motors can draw 5A+, which means you need 6 high current FETs/IGBTs/whatever to control each motor as far as I can see. Isn't that a ton of pcb real estate for such a small aircraft?
>>911981
1 is barely touching the pad, man.
2 has got flux stuck in it, and has barbs/feathers/needles/cracks on the surface sticking out.
too much solder isn't always a problem worth fixing though, unless you're NASA dude.
>>911982
>From what I've read individual motors can draw 5A+
5A? You're kidding, right? 15A is more average. Even 50A wouldn't be a huge amount for a larger RC motor. The really big ones will pull 100A or more.
The power handling section is usually the biggest part of the PCB, but it's not like it takes up much space, relatively speaking. Space isn't much of an issue, anyway; the real problem is weight, which, luckily, the controller doesn't contribute a huge amount to.
>>911866
protip: Heat the piece you want to solder with the tinned tip of the soldering iron and apply solder to the heated piece, not the iron. This is how you get perfect solder joints
>>912009
That's not a protip. That's exactly how you're supposed to solder.
>>912028
That's how the pros do it (supposedly) ergo it's a pro-tip.
>>909883
I found my /diy/fu https://www.youtube.com/watch?v=uCm1iPLVe8I
>>911924
>>911926
K thanks.
Unrelated, but posting a mini 555 motor PWM controller, just in case anyone wants the schematic and board eagle files.
Is there a reason why using capacitor discharge on a solenoid makes it "kick" more strongly?
From what I understand a capacitor doesn't increase the voltage, which is another thing I see people increase when they want to make a solenoid stroke stronger.
Does it have to do with the current being discharged very quickly (over a very short amount of time)?
I need to make a solenoid push strongly for a few milliseconds then retract, no need to keep it on continuously.
>>912161
Yeah, capacitors can provide thousands of amps during a discharge since they have a negligible inernal resistance, the only thing keeping the current down when using it with a solenoid is its inductance and internal resistance.
Batteries have a relatively high internal resistance and the amperage is limited by the chemichal reaction occuring inside them.
>>912161
Small resistances have a larger effect on voltage when current draw increases, even if it's for a brief time. Batteries have internal resistance and there is resistance in the wires running to wall supplies and transformer coils.
Say you have a 12v 2A solenoid and there's a 1Ω resistance to the 12v power supply. When you draw 2A this causes a voltage drop of 2A/1Ω = 2V, so now your relay coil is only getting 10v. A capacitor next to the coil solves this problem.
>>912162
>>912165
How would the current even be increased in this case since the solenoid would have a set resistance which limits the current possible from a set voltage?
>>912168
Maybe the capcitor is being charged to a higher voltage than the battery using a DC/DC boost IC like
http://www.digikey.com/en/articles/techzone/2013/apr/generating-high-dc-output-voltage-from-low-input-supply
>>912170
looks similar to what happens in a disposable camera flash circuit
>>912168
The current increases when you turn the solenoid on. A solenoid is not a simple resistive load. Current draw is much higher while moving the armeture than while holding it in place.
>>911951
https://www.youtube.com/watch?v=vIT4ra6Mo0s&list=PL926EC0F1F93C1837
I've got a computer power supply that suggests I don't put more than a 225W load on one PCIe connector. If I attach a 280W load, is it going to go into current limiting mode and cause instability or is some component just going to get 25% hotter (probably being well within its actual spec but maybe not within whatever factor of safety the supply manufacturer came up with)? I know switching supply circuits vary a lot but I'm sure someone here has a general idea of which would happen.
>>912430
I've accidentally shorted PC power supplies many times. They just shut off, then you've got to wait five minutes before they'll turn back on.
>>912430
It probably has a bimetallic switch that heats up and mechanically breaks open the circuit
>>912430
If it's saying that, it's saying that because it can't deliver more than 225w.
If you attach a 280w load, the voltage will sag, it will no-longer be a regulated 12v supply, and if your 280w load requires a regulated 12v supply, then it won't work properly.
>>912430
Also, 225w is the PCIe standard. The wires, connectors, etc. will be rated to 225w, not to 280w. There's a slim, but non-zero chance that your wires will go on fire.
A device with a six and an eight pin port is only allowed to ask for 225w: 75 from the six and 150 from the eight. Devices with more/bigger sockets than that are currently outwith the specification. If you plug a six and an eight into a device with two (or more!) eight-pin sockets, it can detect that you've done this, and it'll know that your PSU can't deliver more than the official 225w. So if you're planning on doing this, you need to short the two extra pins to ground.
Finally, if your only problem is that you've got a 280w graphics card and a 225w PCIe connector, you're being a ninny: the card's already permitted to draw 75w from the slot, and 225+75=300.
>>912464
The wires are 18AWG so I'm not worried about them, and the limiting factor appears to be the supply rather than the standard. I'm asking to begin with because the supply is going in a very small ITX case and plugging in the second modular PCIe connector would just make it even more cramped.
I know the typical response to "can I do this thing the warning says I can't do" is "no you retard" but there's a distiction between hard limits, and excessively generous factors of safety set by engineers that know these supplies are misused in terribly misbalanced computers built by teenagers.
>>912471
The reason it's telling you not to do this is that the two connectors at the PSU end are being served by two separate rails, which have their own regulators, heatsinks, etc. By using only one wire, you're leaving ~30% of the PSU sitting there doing nothing, whilst another 30% of it works far over capacity.
Also note that the instructions are talking about a "225w GPU", not a "GPU whose PCIe connector pulls 225w". The GPU's getting 75w from the motherboard already, so you're not talking about running at 280w a supply that can do 225w (25% over); you're talking about running at 205w supply that can do 150w (36% over).
PSUs are not known for leaving generous safety margins; they're known for doing the absolute bare minimum required to allow their marketing department to stick another "50w" on the box and not actually technically be lying.
>>912480
Alright then, that's a shame. Thanks for the info though.
>>912471
What I would do, in your position, is make myself a custom cable, that pulled down the required six 12v and six GND lines, but shorted the sense signals to ground at the head end. That way I'd be providing two eight-pin connectors, but only using twelve wires to do it.
The only difference as far as the GPU is concerned is that if the wire is not plugged into a PSU, the GPU will still think it is.
Am I able to substitute the top cable with the bottom one for use with the ac adapter?
Came with a foreign wall plug and don't want to spend money on a travel adapter.
>>912491
Yes.
>>909883
/ohm/
I'm looking for some colored lose LEDs for a project I want to try to create. but I want the LED's kinda like in the OP picture, the REAL leds, not those crappy ones that are white, with a casted color plastic cap.
Mainly. White, Green, Amber, Red.
I need maybe. 50 of each. I would prefer the box shaped ones [I'm not sure what they are called but sometimes I run across them taking things apart so I know they exist, they just have a lower profile.
Hell, at this point If someone knows a place that might sell them in ultra bulk [I'm talking like counts of 500 of each color bulk.] I might shoot for that instead.
>>909883
Does anyone have any advice for working with power supples, like the ones for desktop computers?
What are some things that I can do so that I don't die?
>>912525
It's usually a good idea to not work on shit that's plugged into mains...
Other than that make sure caps are discharged.
>>912519
mouser.com
digikey.com
go nuts
>>911958
In the DIY world maybe...
>>912519
>not those crappy ones that are white, with a casted color plastic cap.
The LEDs you're talking about don't get they're color from white light shining through colored plastic. The diode produces light of a wavelength that matches the color. The plastic is colored so you can tell what color the LED is without turning it on. Manufacturers decided to stop doing this around 15 years ago, which is also when much brighter LED technology became common,
White light (all visible wavelengths) is more difficult to achieve with LEDs than a single wavelength. White LEDs need either separate red, green, blue diodes, or they're really UV LEDs with a layer of white phosphor on top.
>>912562
>pretty much what I said.
why are you quoting what I said then telling me what I'm talking about in detail? I think everyone here who could give a straight answer knew what I was referring too?
as far as the colors go. White doesn't need to be a true white, and can actually be replaced by the red LED's if need be. the amount of brightness is more important then the color of the light itself.
>>912589
http://www.digikey.com/product-search/en?pv37=1707&FV=fff40008%2Cfff80527&mnonly=0&newproducts=0&ColumnSort=0&page=1&quantity=0&ptm=0&fid=0&pageSize=25
Is there a 'let me digikey that for you'?
You or us describing your product won't help very much op, even if you find an example, if it's not on digikey it will likely to prohibitively expensive.
>>912589
>are white, with a casted color plastic cap.
What he was saying is these don't exist.
They don't get their light from the colored plastic cap. They are not white. The LED, the actual diode in there generates a particular wavelength of light. That's why it was such a breakthrough when they could get a very cool blue LED in the late 90s, and then cover it in phosphor to make passable white.
>>912600
>>912604
Let me describe what I'm trying to do here..
I'm trying to come up with a single side prototype tail-light lens/housing design that utilizes LEDs in a manner that doesn't absurdly blind the living shit out of people any more...
So what I'm attempting to do is lessen the amount of light projected out into the environment, but still have signaling aspect readable by DOT standards.
I'm a motorcyclist and when it rains or my visor gets oily from long trips. these newer cars have absurdly blinding tail-lights and auxiliary lights and blinkers [when they use them] that cause a huge glaring issue for me as a rider. and im sure everyone else has noticed this too. I understand what I'm trying to do is diffusing, and is basically nothing new. but I'm trying to keep the light inside the housing. A fish tank effect if you will. you can see all the brightness looking into it, but the light coming out causing glaring issues and such. is much less then it would be with standard LEDs on a grid, and a stupid clear colored plastic lens.
>>912608
>im sure everyone else has noticed this too.
nope
>diffusing
just scratch up the lens. done.
>>912610
Doesn't work, already tried it. still causes glaring issues.
here's what I'm looking for, I searched my box-o-bits for some examples.
>>912614
I think the better option would be to polarize the light and have the motorcyclist helmets have polarized lenses so that way the car doesn't lose illumination and can still see clearly.
>>912589
>why are you quoting what I said then telling me what I'm talking about in detail? I think everyone here who could give a straight answer knew what I was referring too?
relax, scro. consider the pic to be related
#1 shows what are called "diffused" leds. The led package is colored the same as the LED lights up, and the package also has a frosted surface. these are used as indicator lamps because you can tell what color they should light up, and they light up themselves when on, but they don't cast any light.
#2 shows what are called "water clear" LEDs, or just 'clear' LEDs. you can't tell what color these are until they light up--and they cast a lot of light.
{ ~~~ note that most visible-spectrum colors can be found in both diffused and water-clear packages ~~~ }
#3 shows some pink ones I found. I only found this color in water-clear types.
#4 most white LEDs you find are water-clear, but you can also find diffused ones (like this part of the pic shows)
#5 shows some IR leds: the water-clear ones are 850 or 940nm, and the "black" one is a 940 meant to be used as a detector. Years ago (maybe ten years?) the water-clear LEDs were always 850nm and the 940nm LEDs were water-clear but tinged a light purple.. now the 'good' 940nm LEDs seem to be tinged deep blue
#6 shows a purple/IR LED. most are water-clear/tinged purple, but you can find diffused ones too
not shown: you can find RGB leds that are clear or white/diffused
also note: these are just discrete/thru-hole LEDs, smd stuff like WS2812's isn't included in this discussion
>>912623
okay, I dug some of my old LEDs out, because God knows this is exciting shit
pic related: I bought these LEDs long before you could easily get blue, white or purple/UV leds.
The only water-clear leds you could easily get back then was 850nm IR's. The 940nm IR's were all tinged light purple. If that was just a way to tell them from the 850's, I don't know.
That blue one I dunno WTF it is. It's gotta be another wavelength of IR, but I don't remember what. It might be an 880nm; that was another wavelength you could get....
The Radio Shack package may not be 20 years old. It was just close by and including it was an easy way to show some normal red and green LEDs in the picture for comparison purposes.
Anyway,,,,,,, if you are digging around in a surplus store and find a bunch of NOS clear/light-purple LEDs for a really cheap price, they are probably IR LEDs, not UV
>>912562
>The plastic is colored so you can tell what color the LED is without turning it on. Manufacturers decided to stop doing this around 15 years ago, which is also when much brighter LED technology became common,
Did not know this. I thought it was filtered white light too. I think it looks better too - when a red LED is off (on a control panel, say), you can still tell it's supposed to be red so it's probably an indication of something bad, etc.
Hi /diy/
Just got my first soldering iron. Pic related. Going to do some smd stuff with it.
![tumblr_n9a8rrwodN1sfz1xoo2_250[1].jpg](https://i.imgur.com/GH3oQwY.jpg "tumblr_n9a8rrwodN1sfz1xoo2_250[1].jpg")
>>912762
Perhaps now my grandfather can dig out his...
>>912763
It actually belonged to my great grandfather. I found it while cleaning out the basement. Found a bunch of nice old tools. I actually use a Hakko FX-888D and I love it. I used to use a cheap weller station and told myself I'd wait until it died to get the Hakko but the thing would just not die. Now I just use it with an 85w fat tip iron for amp chassis ground connections so I dont have to change tips on the Hakko.
What are anons preferences for irons?
where do you buy your electronics?
in bulk?
pls help trying to build inventory to work with.
>>912782
I use CE Distribution because they have basically everything I need (guitar & tube amp service). You have to have an accout to deal with them, but they have a page that will sell to the general public called Antique Electronics Supply. They dont have much in the way of semiconductors if thats what you're looking for. Mouser and NTE are pretty good for that stuff.
>>912044
Ron should be a national treasure.
>>912782
Mouser
Digikey
Read the pastebin in the OP.
>>912775
Love my 888D as well.
I remember seeing a universal QFP test socket somewhere that looked vaguely like this. Is there somewhere I can buy one of these for a non-extortionate price?
i've been thinking of trying out electronics.
so my friend was an electrical engineer and gave me this power supply, a raspberry pi, cables, some breabboards, a box of solderless wires and circuit elements, and a cheap weller soldering iron kit.
i've got a little bit of experience from uni programming on my pc.
i'm looking for a cheap but reliable signal-generator, oscilloscope, and multimeter.
can anyone suggest versatile models for /diy/ tier stuff / where i can get 'em?
thanks
>>913003
You can implement a signal generator and oscilloscope with the raspberry pi. If you want a real piece of equipment do a search of your local craigslist for terms like "tektronix", "heathkit", and "telequipment". An old analog scope is probably going to be around $100 and a low end function generator could be $50.
>>912996
eBay, or design and order them yourself.
Ongoing OTG cable project with charging option.
Smallest connector I have soldered to date.
Any recommendations for someone who fucked up their engineering studies and now is stuck studying to be an electrician?
Went to uni a couple of years ago but because mental issues and bad habits i failed every course I had and was forced to drop out after the first year. My passion is circuit design, can I get into this without a degree?
Couldn't get a job so enrolled in a program to become an industrial electrician because I didn't know what to do.
>>913070
Go on with your studies until you feel confident enough to take up engineering again
Do not become a NEET if you know what's good for you
>>913070
electricity is serious business, dude, please go be crazy somewhere else, where you cant hurt people.
>>913081
Unfortunately I was neet for nearly 1.5 years, though I'm mostly afraid that I wouldn't be able to continue studying later in life. Job opportunities seems good with what I'm studying right now and it's only a year of studies. I'm just afraid to end up with a job I don't want.
>>913082
The mental issues were anxiety, depression and concentration difficulties. I'm not stupid or crazy. :(
>>910060
Are there any recommended kits for beginners?
Did not see one in the pastebin, just websites with their own kits.
I've programmed in C++ and Java, but it's been a few years so beginner level is the best place to start. Would like to eventually make a touch-sensitive led table for my niece and nephew.
>>913088
>Concentration difficulties
>Working 15kv transformer
Dude....
>>913117
I don't think much of the kits; a lot of it is not interesting. you can just dive in wherever you want
there is a tutorial on the arduino site about making touch-sensors-
http://playground.arduino.cc/Main/CapacitiveSensor?from=Main.CapSense
there is active leds such as ws2812's that let you control hundreds of RGB leds with just 1 digital line. these leds cost about $17 for 100 on aliexpress
if you are familiar with C++ and java, that's enough to start. it's just blinking pins off and on, there's not a lot of high-minded abstract concepts to confuse a person
>>913183
Not going to work on anything over 400v really. :-)
I spent seven hours trying to program at ATMega328 outside of the Arduino breadboard just to keep getting avrdude error messages. I woke up the other day and followed the same procedure on my desktop rather than my laptop and it worked immediately. I'm not sure how I feel now.
>>911034
>Ken Rockwell
probably should be a photographer
What's a really good starter kit for getting into electronics, /ohm/? I got around $150 for this and I'm really looking to get into it
Can you use multiple TRIAC outputs in parallel from a slc500 to drive a load of higher amps than a single triac can drive? I have loads of unused triac outputs.
I am trying to upgrade a home automation setup i have going, and basically im hoping to go from 1 130w heating zone to 4 different heating zones, and using ice cube relays seems wasteful for money and energy (It is a few watts per coil and a few bucks per cube).
>>913330
I got an Arduino and a shitload of any kind of component that sounded cool and was cheap and spent ~100€
Get everything off Ebay or Amazon to save on shipping and you're good to go
Alternatively you can buy cheaper versions of the components in Make: Electronics' kit
>>913340
Arduino is for make magazine kids and artists
get something that works in C if you aren't stupid
>>913347
What's a good starter kit for learning then?
>>913351
don't buy a shitty kit that is already a PCB
start with a project, not a kit
>>913366
Alright anon
What's a good starter project
Help /diy/!
How well will a RC car battery work for an audio speakers driver? The driver is the TPA3110 and it requires and input 8-17V with a 12V switching power supply recommended. Will something like a 9.6V 2000mAh battery work or should I do what it suggests and get a wall outlet power supply? I would like to bring it on the go with me but in the end isn't the end of the world.
Cheers.
>>913369
You probably had something in mind when you wanted to learn electronics
the skill you are trying to develop is designing a project. most likely you will fuck up, you move on to the next one, you know how it goes
>>913369
inserting arduinos into your butt
>>913387
this. dont focus on the skills you want to learn. dont focus on having cool skills to impress the ladies and win friends and fame. focus on what you want. engineering is largely about putting in the least amount of effort in order to assemble commonly available parts to perform some task that an existing product does not do out of the box. you dont need to reinvent the wheel. you dont need to learn how to program FPGAs or even be able to decypher resistor color codes in order to blink an LED these days.
if its just for fun, there are loads of kits available online to help you familiarize yourself with components. I'd say, pick some of them up off ebay, a temperature controlled soldering iron and some solder and go to town. or buy a kit and magazine from an electronics store or one of those childrens toys 100-in-one labs.
pic related, short circuits. its what I grew up on.
Does anyone know what brand this is?
>>913483
https://www.ai-thinker.com/
>>913484
Thank you so much
>>913383
Get a small 12V battery, you can even buy a small motorbike one that will last a lifetime
>>910779
How about 2 magnets on opposite sides?
No need to thank me.
>>911478
I'm going to go ahead and assume you're just getting words jumbled in your explanation of an inductor and not legitimately retarded.
The voltage across the inductor is directly proportional to the rate of change current through it. With an ideal inductor you can have a quintillion amps running through it, but have 0 volts across it.
The reason that an inductor won't form a short immediately even with 0 resistance is, as you mentioned, the change in magnetic field created by a change in current creates a potential that satisfies kirchoff in the circuit. The current will increase as long as this potential is maintained and progress towards a true short (again assuming ideal inductor). However in AC the source only provides the potential in the same direction for a limited period of time, and when the polarity switches the current in the inductor decreases and eventually changes polarity as well. Then it repeats itself, resulting in a current sine curve as well (albeit with an amplitude determined by frequency and the inductance, and displaced by 90 degrees).
The water pipe analogue of inductance is the inertia of the water, which takes time to speed up in accordance with F = ma.
>>911866
Those wires look enameled. Sand the coating off before soldering.
And also lrn2solder.
>>912168
That circuit is an RC, which is completely different.
A power source would likely provide a more stable voltage, but with a higher output impedance limiting the current, the current size being what gives the solenoid it's kick. With a cap in parallel it can provide a lower ouput impedance when connected to the solenoid for short amount of time, increasing the max current that can flow through the solenoid.
>>912762
Point looks too fine, I'd file it down a little.
Could also double as a great bayonet with a backpack power supply.
>>913213
>implying you can't fuck up big time on 400v systems with a little concentration lapse.
>oops i forgot to isolate and ground this cable
>oops i forgot SL&CS
>oops im rip/someone else is rip/i fried 200m of routed cable
I made a simple astable circuit with a 555 and piezo buzzer. Worked fine, I calculated the components for an A note (440Hz) and it's... well, about a quarter tone off, good enough.
Then I tried it with earphones and it goes silent (save for a few crackles).
Is this some kind of impedance related problem?
Also I added a simple passive LPF circuit to it (around 440 Hz to isolate the fundamental - it works with the piezo buzzer (the sine wave is just audible) but when I use the earphones I get a signal but it's a square wave again.
Gotta be impedance right? Do I need to get into op amps?
>>913505
Also, interestingly, in the cases where it didn't work with the earphones, when I connected the positive output to the plug tip and touched the sleeve (ground) with my finger, I got a faint square wave.
Is this my body's capacitance giving the current somewhere to push into?
>>913505
earphones work at around 1/10 to 1/2 volt. i'm guessing you hooked it up directly to the 555 which is putting out several volts, and over-driving it like mad. you shoulda used a 330 ohm resistor, or so, in series. also, a series cap wouldnt hurt, around 50uF.
>>913506
your skin is acting like the resistor i mentioned above.
>>913513
>and over-driving it like mad
Wouldn't that make it louder then?
>your skin is acting like the resistor i mentioned above.
A resistor to where though?
>>913515
As long as it doesn't burn.
555 doesn't like that low loads either.
If you were touching somewhere, there. If not, you have some capacitance to your environment.
>>913515
>Wouldn't that make it louder then?
no, you're beyond loud, and into ''cannot hope to cope'' territory.
so, are you confirming that you drove earphones from a 555 without a series resistor, like a boss?
>A resistor to where though?
one wire was connected directly, the other was connected in series with your body's resistance.
forget about capacitance. the body has like 100pF which at 400hz means an equivalent impedance of 4M ohms. skin resistance, OTOH, is like 5-20K.
Can anyone recommend any good driving boards for stepped motors? I know there's some raspi and arduino ones, but if there's something better I don't wanna buy those just yet
>>913535
>so, are you confirming that you drove earphones from a 555 without a series resistor, like a boss?
Yes.
I wasn't touching the ground wire while I touched the jack sleeve though. I was wearing shoes as I recall, so fairly well insulated.
So I don't think I was grounded. I thought maybe I was one plate of an imaginary capacitor, which allowed some current through.
I ended up wrecking the 555 anyway because I accidentally touched the ground connection with the piezo brass disc (positive) and I must have drawn a wankload of current out of the output pin.
I've got another, but I wanted to experiment with frequency modulation (one controlling another).
I've ordered a ten pack off eBay...
>>913333
Can anyone weigh in on triacs in parrallel?
What kind of power supply do I need to drive led's? There must be something like ballast for leds but i dont know what they are called or how to look stuff up about them.
I'm thinking about trying to build an LED array for a lamp, not to be useful but to play with driving them all with constant current and balancing them for brightness and such to sharpen up on my nuts and bolts bench skills but ill need a power supply I wont mind leaving unusable for the bench because its the lighting.
>>913747
I think I will leave this here for everyone
http://ledlight.osram-os.com/wp-content/uploads/2010/05/AppGuideCurrentDistributioninParallelLEDStrings.Web_.pdf
>>913747
> What kind of power supply do I need to drive led's?
Ideally, constant current.
> There must be something like ballast for leds but i dont know what they are called or how to look stuff up about them.
Current-limiting resistor.
Which is basically what a ballast does (it's just an inductor). But LEDs need DC, and an inductor won't work for DC. The reason fluorescent tubes use an inductor rather than a resistor is that an inductor doesn't dissipate power (voltage and current are 90 degrees out of phase).
Typically, you drive an LED (or a string of LEDs in series) by using a supply voltage which is above the LED's turn-on voltage by a sufficient margin that it isn't substantially affected by likely variations in either the supply voltage or the LED's turn-on voltage. This means that the voltage across the resistor is roughly constant, and so is the current through it (and through the LEDs).
But a resistor just wastes power. For a 20 mW LED, this doesn't matter, but if you're trying to generate a non-trivial amount of light, you want something more efficient. This typically equates to a buck converter without the filter capacitor.
>>913495
>>912240
Thanks for the info.
I decided to take the plunge and buy this solenoid:
http://www.ebay.com/itm/350931123093?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
Is it safe to use a disposable camera flash for the kick or is it safer for me to make my own capacitor system? I know they can drive the voltage up to thousands of volts.
However, if I do make my own capacitor system, how high is it safe to step the DC voltage up to? I was thinking 24V. Is this even necessary?
Well, I failed my electromagnetics course. How fucked am I in the grand scheme of my future EE career?
>>913864
Not very, unless of course you keep failing that course and it prevents you from graduating.
Everyone does. Just take it again until you pass. Then prepare your anus for electromagnetics 2.
![clock[1].jpg](https://i.imgur.com/qxVH0NV.jpg "clock[1].jpg")
hey /ohm/ i wanted to make a nixie tube clock, but i felt like using a kit would be cheating. i was really excited because i think i can develop the clock logic pretty easily, and then i found out that nixie tubes require a lot of voltage to operate... and i then realized that I'm not going to be able to just power them on my own. i found an instructable but... i just feel really shitty using someone else's design. i wanted a project to go on my resume, i wanted serious experience in a lot of the areas i lack in. but because i have next to no experience in electronics i just won't know what the fuck to do.
is there any way i can salvage this project, or should i concede that i'm gonna have to not be original here?
i have an arduino kit, and i powered through all the tutorials regarding the modules. i really want to expand my knowledge, so i feel like i should put in an order.
how do i figure out what i should buy? i want to kinda try out a bunch of IC chips, but there are so many... any advice on what to buy?
>>913886
>should i concede that i'm gonna have to not be original here?
You won't be that original with your clock in any case.
Also, using circuit blocks the others have designed, tested and found working is a part of electronics design in any case.
If you insist on not directly copying anything, then you obviously learn more stuff so that you can design your "own" PSU. There are pretty easy options for that as well, like using a normal transformer instead of some switcher.
>>913888
I guess I didn't mean original with clock design, moreso that I wanted the reward/experience of figuring it out on my own.
I'm trying to learn as much as possible. I'm a 3rd year EEng student with pretty good grades but pretty much 0 practical experience. I kind of... was a lazy ass in labs because I had no idea what I was doing and got through with good coursework.
I'm pretty much hopeless right now.
![LM35DZ-Pinout-Diagram_TO-92_Centigrade-Temperature-Sensor-IC[1].png](https://i.imgur.com/GIWb3QV.png "LM35DZ-Pinout-Diagram_TO-92_Centigrade-Temperature-Sensor-IC[1].png")
Quick question about these things. Is the output always properly calibrated (10mV/degC) no matter what its supply voltage is?
I've been running one off an Arduino's 5V and want to do something with a 9V battery now and I'm wondering if there's anything I need to alter (apart from the obvious).
>>913894
Should since the datasheet does say it is a linear relationship, with a minimal error margin.
>>913896
So if I double the supply voltage the slope of temp. vs output voltage remains the same?
>>913898
Yep, that is what makes it a linear relationship.
>>913901
I'd have thought that a linear relationship just meant it made a straight line on a graph. For all I knew, that line could change its slope for a given supply voltage.
As in you get a particular linear relationship for a particular voltage.
>>913886
generating around 160Vdc is not that hard. you get a 555 oscillator and pump it into a transformer with the right turns ratio, then rectify/filter it. you can pull such a transformer from a disposable camera, electric fly swatter, old scanner with fluorescent lamp, etc.
>>913904
i'm going to have to... google all of those things.
sigh.
>>913902
This is a linear relationship. Notice how the slope never changes?
>>913904
Wait, where is the output on this thing?
>>913906
FFS what I'm trying to say is that I thought there was a possibility that the slope changed depending on supply voltage.
As in, if you give it 5V then there's a 10mV increase per degree, whereas if you gave it 10V there might be a 20mV increase per degree.
Both would make straight lines on the graph, but of different slopes. They would be both linear relationships of differing magnitude.
Now I see that this is not the case, but the term "linear relationship" doesn't mean "slope never changes according to one of the parameters", it means "there is a line of some slope, which may or not change with one or more of the parameters".
>>913908
Okay, that makes more sense. The 10mV is the constant part of the slope.
>>913910
Cool, just had to be sure.
>>913912
I am curious, did you look at the datasheet?
>>913913
I must confess, no.
>>913907
ah! so you wanna build a high-voltage device but you cant even read a simple schematic. this is not gonna end well.
> I'm a 3rd year EEng student
wow. only in Amerika.
>>913925
I wasn't that guy, but usually when I see a schematic the source is on the left side and the output is on the right.
>>913930
same applies here, output is where it says -(3-5)kV. you stick your tongue there to test if it's working.
>>913931
That is what I thought, but I am curious of why the diode is reverse biased?
>>913933
it's not. it points that way coz the designer wanted a negative voltage. coz they're 30% more effective on tongues.
Picked up a pair of Butane soldering irons from Hofer today.
They're the Workzone brand PT609B and they cost 20€ each.
The Catalyst and general construction seems to be very similar to the one you'd find on a Weller Pyropen. And the tips from a Pyropen also fit.
They seem pretty good to the touch, rather nice to hold too.
I'd recommend you guys give them a look if you've got a Hofer/Aldi in the area. Seems pretty good price/performance wise.
>>913756
Thanks, I've got a schematic drawn up based on this. My estimates are giving me around 8W of 'wasted' power on my resistors on a 180w array. does this seem good enough/decent or should i leave well enough alone?
The circuit also includes a current mirror between all the strings if that matters
I figured this would be a good place to post this.
I'm trying to use use toggle switches in my car to power two amplifiers. I want one amplifier to only be able to be on when the other is on, but to be on at my discretion. I know I can do this in a very straight forward way by wiring them in parallel like in pic related, but I got to wondering if I could do this with only one switch with a OFF-ON-ON(double on) configuration. Is this possible? If so, what kind of switch should I get and how should I wire it?
>>914004
DPDT switch, maybe?
>>914008
I think I understand what the switch does, but I don't understand how it would help.
I want something like this ideally
OFF <----> Amp 1 ON <----> Amp 1+2 ON
I initially thought something like this
http://www.amazon.com/gp/product/B00004WLKA/ref=s9_simh_gw_g60_i4_r?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=desktop-5&pf_rd_r=0RRM34D5QWJZ00N1KH6G&pf_rd_t=36701&pf_rd_p=2090149782&pf_rd_i=desktop
would work, but I'm not so sure anymore
>>914012
You want a DPTT switch.
>>914012
http://uk.rs-online.com/web/p/toggle-switches/7109860/
something like this
power to pins 5 and 2
amp1 to pin 4
amp2 to pin 1
system will be off in one extreme, amp1 on only in the middle, amp1+2 on at the other extreme.
no guarantee that switching from amp1 to amp 1+2 won't interrupt power to amp1 however you will need to check the datasheet.
>>914012
i dont think this is possible to do without diodes, because, whatever way you wire a switch, the power lines for each amp have to merge at some point.
drawing shows how you can do it with a Radio Shack, model 2750325, center-off switch.
>>913925
>implying that's not poorly notated china shit
