Introduction: My Suped Up PowerSupply!

Inpired by other powersupply projects, I decided to build one myself, and ended up adding a lot of junk. See the steps on how to build one.

Step 1: Get a Powersupply

This is an old powersupply I got free from my school, and it pumps out 2-22 Amps on 5-V and 0-9 Amps on 12-V. Plus it has a automatic shut down circuit that shuts down the powersupply when short circuit is detected (it barely makes any spark when you join the positive with the negative).
You can get a powersupply easy from any computer repair shop, once you have your powersupply, it's time to put it to work.

Step 2: Safety

There are many ways that you can electricute yourselfs when doing this project, so please take the following precautions building this project, and don't get shocked and get a big blister like I did.

**NEVER EVER WORK ON YOUR POWERSUPPLY WHILE IT IS PLUGED IN**
*The capacitor inside holds enough electricity to cause an extremely painful shock, so discharge these capacitor with a power resistor with resistance over 10k ohm, just bend the resistor leads to the capacitor leads on back of the circuit board and make sure you hold the resistor with a pair of pliers because they tend to get very hot.

Step 3: Planing

Most old powersupplies have a heavily insulated line that have two wires in it, when these wires are connected, it turns on the powersupply, and is usually connected to the powerswitch of the computer. If you want to use the switch it came with, then be my guest, that is what I did, but it looks a little bad. If you want to use another switch, then cut off the existing switch and add your switch to the two wires.
For the output terminals, leave nothing but 4 strands of +5V (RED), 4 strands of +12V(YELLOW), and 6 strands of common negative wire(BLACK), if your powersupply has a 3.3V output, then you can leave out 3 strands of that too(ORANGE). Feel free to use more or less strands of wires for your output, the more you have, the better it will handle when pumping high currents.

Step 4: Putting It Together

Most powersupply has a minimal out-put current, for my PSU it is 2 Amps across the +5V. If you turn on the powersupply without any load, it might just burn out or have a wild voltage. So, I chose to buy a 10Watt 10Ohm resistor to consume that 2 Amps. I also found that it heats up so much that it started to smoke! So I decided to fancy it up, and added a big heat sink from a TV, and a cooling fan from another powersupply, even with all that cooling it still heats up to about 40 degrees C* on normal operation. I also added 4 super-bright LEDs connect parallel to the resistors and a 0-5k ohm pot to adjust the brightness. All that takes up 1 wire of 4 +5V wires that you left out, and 1 of 6 negative wires.

For the indicator LED mounted on my case, I used a 512ohm 1/4watt resistor and a green LED connected across 12 volts. that takes out 1 of 4 +12V wires you left out and 1 of 6 negative wires.

And now your left with 3 RED, 3 YELLOW, and 4 BLACK. I twisted them and used electrical type to finish it off. The terminal is solder connected to 20Amp Heavy Duty Alligator clips.

Step 5: Put It Through the Case

Plan how many hole you need to drill in the case, like the switch hole or the indicator LED hole.

Fit all your out put wires through the original hole and hot glue it shut so you won't be able to pull it out of the circuit board.

And Walla, your done! Make sure it is properly grounded, plug it in and turn it on.

Please post and questions or suggestions. I will be around for the next 2 weeks.

Comments

author
russ_hensel (author)2015-01-09

Just a note to let you know I have added this instructable to the collection:
Encyclopedia of ATX to Bench Power Supply Conversion
>> https://www.instructables.com/id/Encyclopedia-of-ATX-to-Bench-Power-Supply-Conversi/
Take a look at about 70 different approaches to this project.

author
coleyy (author)2011-01-10

you could also find the big 20 pin connector, find the green wire, and jumper it to any black wire on the same connector

author
BC-45 (author)2008-03-26

if discharge the capacitor from power suppply is it safe to remove

author
lemonshark10 (author)BC-452008-05-21

just put a screwdriver between the leads if it is small. say the size of a camers flash cap.

author

its not a very good idea to do that. the output from the capacitor can melt metal as well as damage the capacitor.

author
sora (author)rocketman2212010-08-15

and cant enough electricity make a magnet out of it?

author
rocketman221 (author)sora2010-08-18

You need a coil of wire to make an electromagnet.

author
sora (author)rocketman2212010-08-20

you can make a permanent magnet out of lots of voltage running through a piece of metal or wire that's how some magnets are made

author
panmil1992 (author)2010-06-24

You can always use a 100 watt bulb or two in series if capacitor voltage over 400 volt. It's the best way to discharge them.

author
Junkyard John (author)2006-06-26

A word of advice! DO NOT USE SCISSORS OR SCREWDRIVERS TO DISCHARGE CAPACITORS!!!! I HAVE TRIED THIS AND THE SCISSORS HANDLE MELTED!!!! a little extreme I know, but it it did happen. I got a two degree burn for my stupidness. I have also heard reports of people who have had bits of handle of a screwdriver fused to thier hand from doing this. INSTEAD, BEND THE LEADS OF A LARGE RESISTOR, HOLD THE CERAMIC PART OF THE RESISTOR WITH PLIERS, AND TOUCH THE LEADS TO THE CAPACITOR LEADS. DO NOT USE A REGULAR PIECE OF WIRE AS IT WILL RESULT IN A VERY LARGE SPARK AND DAMAGE THE CAPACITOR!!!

author
GoodAtIt (author)Junkyard John2006-06-26

I think a capacitor you discharged might be a huge ones, but not the size of the capacitor used in a power supply. A typical power supply cap is only about 450uf at 200V, it is impossible to melt scissors or screwdriver metals. Like the cap bank shown in the picture, its 3 cap connect in parallell each rated at 40V 80000uf cap, I charged to 25V and discharged it with a screwdriver just for fun and it did melt the screw driver to the capactor terminals and made a huge spark plus deafening noise. It is correct to take precautions around capacitor specially discharging them, for I have injured myself many times.

P1040838.JPG
author
GoodAtIt (author)GoodAtIt2006-06-27

Here is a picture of me discharging one of them charged to 9 volts. -Woot-

Capacitor.JPG
author
Mudbud (author)GoodAtIt2009-12-24

were does everyone get these awesome caps?!?!?!?!!?
i want dibs man.

author
goeon (author)GoodAtIt2009-03-01

loud?

author
westfw (author)GoodAtIt2006-06-27

450uF at 200V is a substantial amount of energy. 9J by my calcs. That's (slightly) more than the average disposable camera flash, and they produce impressive sparks like at http://www.quaketronics.com/
The caps will PROBABLY be mostly uncharged when you short them, but a resistor is still a good idea. (don't forget that the energy equation has V**2,
so a cap charged to 100V has 16 times the energy of the same cap charged to 25V)

author
izidor7 (author)westfw2009-04-23

i can just imagine what for a bang would make a 2,5V 3kF cup 10 000j maybe the bang wouldn't be big????

author
legless (author)Junkyard John2009-04-23

Also even low voltage capacitors can be discharged quite successfully using a household mains rated lightbulb.

author
rcguymike (author)2009-07-28

on the psu I'm using it has a blue, purple, brown, grey, and green instead of 2 "heavily insulated" wires. is there a way to find out which ones turn it on or has anyone used one of these. it's an ACBEL API-9635. thanks. On further examination of the PCB where they connect to it the blue says -12 Volts, purple says +5VS, Green says ON/Off, brown isn't even connected(wth), and grey says PG. would that mean connect grey and green with a switch?

author
marshnt (author)2008-09-30

whats with the leds r they doing any thing important

author
bylerfamily (author)marshnt2009-06-13

No.

author
marshnt (author)bylerfamily2009-06-16

So this is just an worthless light. "yawn" Go kill ur self

author
bylerfamily (author)marshnt2009-06-17

No,the LEDs don't need to be there but the power supply can be used for various projects.

author
junits15 (author)2008-10-04

wait im confuzzled so im taking the psu apart and removing all wires except red black and yellowi got that much, then i put the corrisponding colored wires together as one? and this gives it more power? plz help me!

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bylerfamily (author)junits152009-06-13

Yes.

author
junits15 (author)bylerfamily2009-06-13

ok

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Lectric Wizard (author)2009-05-25

Are you sure you have a 10ohm 10W resistor ?? Ohm's law says I=E/R =5v/10ohms = .5A & P=E X I =5v X .5A = 2.5W . That resistor should get warm but not that hot. I have done this a dozen times & all I did was ty-rap the resistor to the inside of the PS case ... NICE INSTRUCTABLE THOUGH !!!!

author
carebare47 (author)2008-01-01

i took two capacitors from a power supply. they are quite small, but rated at 220uf and 200V. i am charging them with 4 9v batterys and the most i can get out of them is a small spark. What have i done wrong? i plan to use these for a railgun i made two years ago, the capacitor bank for that was given to me but fell apart. please help

author
GoodAtIt (author)carebare472008-01-01

if you want to see big spark, you have to charge your capacitors to at least 30V. From my experience, shorting a high voltage capacitor is incredibly loud, so I just stick my my 40V 80000uF caps.

author
carebare47 (author)GoodAtIt2008-01-02

so what would I charge them with?

author
carebare47 (author)carebare472008-01-02

And also, would I damage them by shorting them out a lot?

author
carebare47 (author)carebare472008-01-02

acctually, i am charging them with four 9V batterys, thats 36V isnt it? so why isnt it working well?

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GoodAtIt (author)carebare472008-01-07

Check if you connected the 4 9V batteries right. They needed to be connected in series in order to have 36 volts. If it still doesn't spark big, then you need to go a bit higher, and it won't damage them by shorting them many times.

author
klee27x (author)GoodAtIt2008-08-21

Yes, it might. Some capacitors are specifically made for high discharge, such as used in flash cameras. Many other kinds will be damaged from being shorted, repeatedly.

author
legless (author)klee27x2009-04-23

Just remember that the capacitor in a camera flash is not being "shorted" as such. When you hit the button current flows through a load made up of the Xenon flash tube and a couple of components. A dead short just using a wire is a completely different thing. The short circuit is a theoretical load of zero ohms (not in reality) allowing an almost infinite amount of current to flow (again not in reality). There is some resistance in any wire and some internal resistance in a battery or capacitor. Still the amount of current flowing in a short circuit can be very high even if just for a brief moment.

author
carebare47 (author)GoodAtIt2008-01-08

i had wired them up positive to negitive to positive to negetive, and they do charge and spark, but its really small. oh well, nothing 2 liters of petrol cant fix. Thanks for the help =]

author
spasysheep (author)carebare472009-04-06

If you connect several capacitors together, they act as one capacitor. In series (what you're doing) they work at a higher voltage, but lower capacitance (http://www.play-hookey.com/dc_theory/series_capacitors.html). In parallel, they have a higher capacitance but lower voltage (http://www.play-hookey.com/dc_theory/parallel_capacitors.html)

author
chip123 (author)carebare472008-07-31

i read this somewhere, but i'm not sure if it's true. A capacitor can only give an output of the equivilant to it's input, so if it holds 200v, then that is what it needs to be charged with.

author
spasysheep (author)chip1232009-04-06

If a capacitor is rated at 200v, that's the maximum voltage you can *safely* charge it with. If you charge it with 50v, it will output less power than it would if you charged it with 200v, as you put less power into it. If you charge it with 500v, it will burn out / malfunction / explode.

author
Muscelz (author)2009-03-05

dude, wow so messy :S duct tape, a kids workshop

author
Callum Snowden (author)2009-02-16

I once read that a capacitor can regain it's charge after a couple of minutes so it's probably best to grab some croc - clips and clip on the resistor.

author
Derin (author)2009-02-08

It is there and that low because PSU's tend to not work without a good load on the 5V bus.

author
GoodAtIt (author)2006-06-27

Anyways, it is a safety hazard to discharge a capacitor with a high conductive material, and I will change it. But most powersupply even some of the older ones have automatic cap discharge system that initiates once the power supply is shut down. If you measure the resistance between any positive terminal to the negative terminal, it will be close to 0. Thank you for you concers guys.

author
iBurn (author)GoodAtIt2008-10-16

mine are zero.

author
Mz3FRS (author)2006-09-13

This project will make a good bench power supply to test/run other electronics projects. I used a similar method to power some thermelectric coolers I was playing with awile back-works great. Nice write up!

author
junits15 (author)Mz3FRS2008-10-04

how did it work when u powered the TECS? did it cause the psu to shut down?

author
Mz3FRS (author)junits152008-10-05

Nope, it worked fine, just don't exceed the max wattage on the back of the PSU

author
ll0ll (author)2006-08-24

sorry to be ask a stupid question, but why do this? What would you do with your modded PSU? .. Thanks

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jinventive (author)ll0ll2008-01-02

It just modifies a regular computer power supply into a bench-top power supply for electronics.

author
binnie (author)ll0ll2007-06-09

If you have to ask... its not for you