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Convert A Computer Power supply to a Variable Bench Top Lab Power Supply
Things to do with a old computer
I took my advice and looked it up--the internet is wonderful that way. It seems my memory is faulty or the information has changed since I last checked. It is 10ma of AC that is the "let-go threshold" (can't let go) for a 150 lb (68 kg) human. The skin is where the most impedance is (I erroneously said resistance before) the the impedance of the skin varies and can be lowered to almost nothing under the conditions I previously mentioned. Domestic power supply, 120 or 240VAC, 50 or 60 Hz through the chest for a fraction of a second can cause currents of as low as 30ma, and can cause ventricular fibrillation (heart attack). More than 200ma causes the heart to contract (lock up), no fibrillation, 300-500ma DC.So, .5 amps DC can kill but if anything lowers the impedance of your skin it takes a lot less voltage to cause that .3 to .5 amps.
WanderingAuthor is correct about the 12V car battery. 60 milliamps is the magic number. The human body's resistance can be as low as approximately 200 ohms if they are tired, sweaty, ill, and/or several other things. That's 60ma at 12V. A long time ago the U.S. Navy considered anything above 30V as high voltage because it was possibly lethal. Before I joined the Navy in 1970 the official voltage had changed to ANY voltage. I know of a CPO that was electrocuted while installing a stereo in his car, by 12VDC! This info was in an official Navy message. Just because it only zapped you and you survived does not mean it's not deadly. Also AC is more dangerous than DC because DC will stop your heart while AC will cause it to fibrillate (vibrate instead of beat). It's easier for someone to start a stopped heart than to get a fibrillating heart to beat correctly. 120VAC is more dangerous than 400VAC because 120 will cause you muscles to contract and keep them that way, if it's your hand (palm or inside part of fingers) it will lock your hand onto the wire or whatever (if it is small enough to grip). 400 volts will simply knock you across the room.If you're messing with electricity you should be smart enough to look up the correct information! You even have the internet to make it easier. I had to learn this from instructors and books.So, please quit spouting BS! It's dangerous to the people that believe you.
I used to scavenge and rebuild all kinds of computers from the discards of others. My present main machine is an AMD64 X2 someone tossed, in the case of a dead Dual-code-quad, with 6 internal drives (2x1T, 2x500GB, 1x 160GB & a 80GB main drive.) 8GB of RAM, a Gigbyte Invidia 1GB graphics card, with a few extra cards. ALL scavenged! Alas, the town I used to live in, began a 'Mandatory E-Waste Recycling' program several years ago, and, I can no-longer obtain the parts I used to.. (All devices, once placed in the bin, become property of the town, which then sells it off to a E-Waste recycling/recovery company. After all of the precious metals they salt out, I can only imagine the amount of caustic and contaminated waste they still need to dispose of? So-far, UBUNTU, and a few varients (Ultimate Edition, KUBUNTU, etc..) run right out of the box (as long as you run the x64 of x86 version to match.) I've been running Ubuntu for about 2 years now, main machine running 16.04 x64, I totally agree! Unless there is actually something physically broken (burned out, over-cooked, (Too-clocked)), too many people toss out, wanting the latest, greatest, fastest gaming machines.. My main machine would've qualified as one of those 6-8 years ago, but it runs just fine! (and it runs OpenArena 0.8.8)
Hello, I need 12v 5 amp current from a pc smps. What I need to do?
Motherboards: You can make a growing city out of that! Just unsolder everything, then just go randomly plotting resistors, capacitors and etc...every day you plot something... *also, just to give it a cool look, paint the components in one or two colors*
i just built it and all my multimeter is showing is a variability from 0.3 volts to 1.5 volts what did i do wrong
Hi, I made this project. I also added a 2 port usb i hacked from the same old computer. I simply connected green (power on) to GND (black) to make the original switch work. This case I don't have the above mentioned 5V when plugged in but not switched on. I consider working on that to i order to power the usb port.My observations:The PSU itself gives only 23V. After adding the variable circuit with the LM317T it dropped another 1V, so the schematics states correctly (in my case), that output is 22V. Problems to clarify:I observed a .1 to .3 variation on the voltage output. I have a suspicion that it could come from my digital multimeter, so I made the following steps to verify:1. I wired a 1K load on the output. Result: around .5 volt dropped but still varying .1 to .3.2. I measured with an analogue display multimeter. Result: stable.3. I wired a 24V 50W halogen bulb to it. (This was at hand). Result: visually stable. Ampmeter showed steady 1.5A.4. I took measurement on 5V (red) and GND (black) on the PSU itself. Result: variation.I'm still concerned with this variation. I will test it with other multimeters when I have the chance, to determine whether it is a measurement error or not.
u mixed -12V & +12V regardless current sourcing, -12V is usually so small sourcing current!
need help with this? can you help?
Hello All,I have created this about 2 days ago and all went great. It was working fine and I was very happy with my project. But then I was testing some circuit with led diode and I have increased the voltage by mistake while the circuit was still connected. LED Diode of course blow up :) but also my power supply is somehow damaged. I will transfer the symptoms to you and hopefully someone will provide me with possible fix:When I turn the switch ON it doesn't run (only the fan will try to run and at the same moment will go off. Please note that I do have 9W47ohm resistor as a fake load between GND and 5V (black and red wires). I know it was suggested to use 10ohms but I couldn't find one and this was perfectly fine. Just to exclude the resistor as a possible reason. Also please note that the issue started to happen after the incident) If I connect some DC motor that operate with let's say 18V, and then turn ON the switch, it starts working but the minimum voltage (on the regulated outputs) is 12V and not 1.2 as before and it only goes up to about 14.6. Basically that is it, just I am not sure how to fix it. I did one mistake I didn't used PCB because I considered it to be fairly simple project, but now fixing will be real pain. I will now create PCB so if there is a need for future fixes it will be easier and faster.I would be really thankful if someone suggest what could be damaged and how to check/test because although I do have some general knowledge, I am far from being expert in electronics. Thank you in advance. - AleksandarI4
Hi.codegen 350W. I have the resistor on 5v line and about pc. 12V yellow 12V wires connected. I only need 12V for my lipo charger. Psu gives out about 2amps now. On the side label ot states that 12V out is 15A.any tips to get hihher current output ?. - MikkoK7
i would suggest you use maybe 3 wires, at most, of each color. any more than that and it is a waste. just cut out all the lead wires, and leave only 3 of each color and you'll be good to go.
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