Make a bench power supply mostly from recycled parts

Picture of Make a bench power supply mostly from recycled parts

This instructable will show you how to make a very good bench power supply using mainly recycled parts. This is the really the "mark II",  you can see "mark I" here. 

  When I finished my first bench power supply I was really happy, and used it very often, almost every day, until one day it decided not to work anymore, :(  so... I realized I had to do it all over again, including the not that easy drilling on the metal of the ATX, etc. So this time I'm making a bench power supply that you can replace the ATX in no more than 2min.

  Last time I did not take any pictures of the process, so  I could only do a slideshow of the finished product, but this time I took lots of pictures, so I did this Instructable, which I hope you'll like.

  May you decide to go ahead and build your own?... I would like to take the opportunity to say that I will be more than happy to help you with any questions you have, and also I will love suggestions so I can improve either this instructable or the bench power supply itself.

  As the title shows, with this instructable I want to encourage people to recycle. There are lots of things around the house or even in the streets, that you can take components off, and use them later to make so many interesting things. I used as many recycled parts as I could for this project, and if you do the same, you could have a very powerful and COOL! bench power supply for almost nothing.

OK.. lets start with a view of what we will be making....

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Hi Newton,

on your wiring diagam is it only two legs from the potentionmeters that be attached to pcb.

plus i am using 15v per side ie negative and positive so do i need to up the potentionmeter values??

my 5k potentionmetrs keep burning out and i see a light in it!!!

do i need to use 10k ones so it can control the voltage an using.

please let me know.



newtonn2 (author)  vimajksyesterday
Hi Vim,
You need to connect the middle connector and any of the other to. Other ways you are making a shortcircuit.

Let me know if that fix your problem


I made an AT based supply that didn't work for me. I have an enermax ATX high end PSU and figured I'd go all out on a fancy bench supply unit. I'm getting really frustrated. I thought that someone could enlighten me as to the weird results I get.

1.The PSU came with 2 fans and when connected they both spin slowly, Normal?

2. Connecting the green and Ground wire through a switch makes no difference in how it operates.

3. Not a real problem, but, connecting the Orange wire (3.3v) to the Brown sense wire through a power resistor only seems to stabilize voltage slightly.

4. The voltage readings I expected are not at all what I get.

GND - orange= 818mv , -5v-+12v= 20v, -12v-+12v=19.03v

GND-red= 3.5v, GND-+12 = 19.00v.

I built a variable LM317 based voltage regulator connected to ground and +12v (yellow).... It provides 1.2v-17.86v. It works great but most other terminals don't supply anything near what should be expected.

Any insight would be greatly appreciated!

bswt2 months ago

can i use the M9052 LM350K STEELP+ in this voltage regulator

junior_085 months ago
can u help to do the same box like urs i like tht one
cheegi8 months ago
I think you can use step down regulator with L200 with external transistor. huge power supply need if you load high current
zacker10 months ago
lol.. I like that you put "English is not my first language" because... Electricity is not mine! lol,lol,lol... +12v, -12v, +12 VB DC, +12 VA DC / SE what the heck?
Yes these are listed in the pin out diagram for my Dell PSU!
zacker10 months ago
wow...came out very nice!
newtonn2 (author)  zacker10 months ago
Thank you very much!
zacker newtonn210 months ago
lol no problem... Now Im getting all sorts of Ideas about making a box for the one im going to be making, once I figure out all the wiring. I especially liked the Amp and Volt meters you have in yours, the blue lights look great. Now those measure what's coming out of the PSU correct? So if you hook it to something, and you want to see how many Amps or volts its pulling, boom! you just look at the meters instead of getting out the Multimeter. Nice!
redman881 year ago
looking at a few other instructables and i found why you need the 10ohm resistor,
KylerKraus1 year ago
nice instructable and good results.

I need a power supply that will vary volts and amps. could i put a pot on one side of the output and vary the amps that way?
newtonn2 (author)  KylerKraus1 year ago
Hi there! Unfortunately you wont be able to adjust the current with just a potentiometer. Adjusting the current is more dificult than the voltage.
PREngineer1 year ago
Hello Newtonn2,

This is a great Instructable. I'm a Computer/Electrical Engineering student and I need a Bench PSU and this looks great.

So far, I'm doing small circuits with LEDs and it seems to me, the amount of current the ATX provides is ridiculously high for this type of circuit.

Question #1:
Does the ATX PSU regulate the amount of current it gives out according to the LOAD or is it the fix amount it states it gives out?
I've noticed that with the regulator you put, whenever you change the Voltage, the Amps also change... Does the amount of AMPs for 12V it gives you is safe for LEDs?

I was thinking if there was a way to regulate the amount of current that it outputs so that I won't be burning every LED I put in and I found this schematic for a current regulator:

However, I see the Resistance that controls the amount of current is very small (<1Ohm)... so there is no way for it to be substituted by a Potentiometer which will give me control... Also, I think it affects the voltage.

Is there any way I can fix the Voltage, let's say at 12V and regulate the current?

mobilohm1 year ago
rj_schad pointed some error but I don't see any answer to his comment... so what should one think today?
Bio9611 year ago
i don't understand . Before conecting anything all the wires of the same color that come out of atx have to be soldered together ?
rj_schad1 year ago
I believe you have a small error in this schematic: the 10uf cap coming off the output from the LM350 has the ground connected BEFORE the 5k pots causing it to become in parallel with 560 ohm resistor and share the same voltage. Im using a LM317 that puts a voltage of 1.25v across my first resistor (560 ohm) on the voltage divider, which matches the datasheet from The negative end of the 10uf capacitor should be connected AFTER the second 5k pot.

Also when plugging in any iphone or ipod the 5 volt on the usb connector isnt enough. At least for these two products, the two middle data pins need to pulled to logic high (using the 5v source and large enough resistor).

Otherwise great tutorial.
Newton, This year I am taking your design and putting it into a clear acrylic case, so I will send you some photos when I get it finished..I ordered some new panel meters like yours..the ones I had were not back lit, and I liked the ones you used.
Thanks again for sharing your project..and after a year the only thing I had go wrong was I blew the fuse on the PSU, But I put a re set type of breaker on now I can just reset..and go.
Got most of the front panel done, a few more things to add..but here is what it looks like so far
Bench top front panel.jpg
Added tags
Bench top front panel.jpg
newtonn2 (author)  paradise974021 year ago
Wow! It looks very cool on fiiberglass! I like it.
Ok, I taped the case together to check it for space (Great..lots left) so I am going to add some spare cold cathode lights I have in a box of parts. Still have the relay, a cpl fuse boards, another power supply (smaller one) and the buzzer for the continuity tester, the USB outlets and some other stuff I have yet to think up.
Test fited case.jpg
No I am using all clear acrylic. I have updated a few of the components and went with the same style meters you did( I like those alot better).
Plastic is alittle tough to work with, get some cracks and chips..but after I get it all assembled, I am going to go ahead and re make the front cover. But I made a holder for the multimeter and a few other everything is clear.
I am going to use a power supply from an old DVD player to power the meters and a cpl other parts to seperate them from the other supply, and am going to use external fuses instead of the soldered on fuse on the power supply.
Now just to make it all look clean?
But I am still working off your design of re use parts where I can. even though its a new look..its still a Newton Bench top power supply!
additional question: when i used +12v and -12v using lm350 as regulator, why do i get 12v as an output, following your schematic..
how much is the max amperage of your power supply?
yoyology1 year ago
I'm thinking of making something like this using a big cigar box I have in my shop.

I want to make one set of outputs dedicated to 12V, one to 5V, one switchable (using a multi-position rotary switch I've salvaged) and then one more variable.

What I'd like to do is put a switch after the multi-position switch that will toggle between a straight line to one set of outputs, and a line with an in-line potentiometer to the other. That way I can adjust the output precisely. (See the block diagram below).

I'm just using the pot to dial down the voltage, instead of your voltage regulator circuit. I've tested the pot already from a 15V 1A wall wart, and it seemed to do fine. Will there be problems doing this over time?
newtonn2 (author)  yoyology1 year ago

You can't use a potentiometer to drop down the voltage, it will burn with load. A Wirewound potentiometer will do a bit better but not good enuf. The best way to do it is with the power regulator.

Sorry I took some time to answer.
That's okay. I suspected as much, but wanted to be sure before I proceed. I'll need to dig through my parts bins now to make the regulator circuit. :-)

I'll post pics once I have the whole thing together.
amarquez4 years ago
OH NOOOO!  Another PC Power supply conversion article using power resistors...   :(

 we go again...

In any PC power supply you MUST have some load to make it function properly...  say, the 12 V output usually stays below full 12 V unless there is SOME load.  That is the reason people converting ATX style power supplies put a load on the 5V branch. (Mine puts out only 11.85 V when there is no load on the 5 V output...)

NOW; using a power resistor IS NOT THE BEST WAY. period.

The 10 Ohm resistor draws a lot of current from the 5 V circuit, and PRODUCES A LOT OF HEAT !...

NOW, if you use an automotive taillight and turn signal bulb, and place it in a socket, you can place a nice three level load.  Using two small switches, you can wire each of the two filaments to the 5 V output, so that you can power one, the other, or both filaments together; so that you can put just enough load on the 5 V circuit, so as to make the 12 V output produce something more than 12 Volts, so that your battery charger, car stereo. HAM Radio (or anything that you decide to be fed by your ATX power supply) will work perfectly.  My Triton2 battery charger can now put out a full 6.5 amperes when recharging a common 12V car battery, a task  it wasn't designed to do, but it does easily!  It can work for hours and more hours at full load without a complaint.

The automotive bulb has MANY advantages, it doubles as an easily seen pilot light, it produces much less heat to the inside of the enclosure, since it is now fed by 5 V, it will last many many hours.  The glass bulb is gas filled at a low pressure, which becomes an excellent heat insulator that keeps the glowing lamp filament from overheating the inside of the ATX enclosure.  There is NO need to use any kind of heat sink.  I have converted several PC power supplies for my friends, and have put the socket and bulb inside the original ATX power supply enclosure, locating it between the inside heatsinks directly on the airstream of the fan, so that it never heats the power supply components.  When it is working, the bulb in my PC power supply stays hot to the touch, but WAY MUCH LESS HOT than a 10 Ohm resistor!

Forget about using 10 Ohm wire wound resistors, they overheat too much and can melt some wire insulation or the nylon ties used to hold them in place.  The automotive socket and a two bulb package costs less than two dollars or less!

Been there, done that!

Happy new year everybody.
amclaussen, Mexico City.

Exactly what i was thinking about.
why have a 10W power resistor at 10 ohms that will just be producing heat and using alot more power than needed
yes now i dont need to buy a power resistor from another shop thanks :) :) :) :)
techxpert2 years ago
so all the connectors are only needed if you want the psu back :)
kasatka69912 years ago
hello newtonn2 im kasatka6991
been building cheapo's psu out of old atx for some time and ran across your design
in a word marvelous
my only need is that i want the amp output to run as high as my psu will put out
antec true 430 watt psu
dc output +5v @ 36Amps +12volts @20 amps +3.3 volts @ 28amps
this is the big deal for me as i test and rebuild car power amps
some of which draw 15 to 20 or more amps at peak levels
the old unit we had at the old shop i worked at had a variac adjustable voltage and amps outputs
so to my question how can i create the same function usin you design if possible but get more amps instead of the 3 amps or so from the lm350 controler
any advice is desperatly need as i cant afford 700 buck for a comercial unit
thanks kasa
pfred22 years ago
Your supply came out looking really nice. I like the stylish rounded top and bottom. A breadbox I've have never thought of that!
shadow14892 years ago
Hey Newtonn2 , I am in the process of building the bench power supply from your information you posted but there seems to be a step missing that i cannot figure out, I got to step 8 and umm yea I'm stuck ,, any help would be appreciated
Paulvinn2 years ago
Thanks for the great instructables! I just finished my bench power supply that is based on your instructable. Mine maxes out at twelve volts. I cant figure out why. Also i just order parts to build an lcd projector. It takes a month to ship parts from Hong Kong! Anyways thanks for the cool projects.
harvey6394 years ago
Hi newtonn2 i am in the middle of making one and i followed the link to ebay for the meters the only problem is that I don't know how to connect them can u please send me a circut diragram  via my email that would be really helpful thanks.
newtonn2 (author)  harvey6394 years ago
 There is a schematic on the step 8. If you need more information contact me.
newtonn2 Excellent benchtop by far the bast on the web. I just bought or salvaged everything I need to make it except for the panel meters. Your links are no longer attached to the parts you bought. What precision collision mentioned sounded good using meters with shunts that doubled as the power source when used.

Do you know what would be best to purchase?

I would be very grateful for you help.

I will shop in meantime.
newtonn2 (author)  mat_adl2 years ago
Hi there!

Sorry the kinks don't work any more. They are a bit old.

check this links...

They need an external power supply, (9v) but don't worry to much about the consumption as mine still working with the first battery.

best regards

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