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Make a bench power supply mostly from recycled parts

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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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vimajks3 months ago

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.

cheers

vim

newtonn2 (author)  vimajks3 months ago
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

Isaac
Homepwner3 months ago

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!

bswt5 months ago

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

junior_088 months ago
can u help to do the same box like urs i like tht one
cheegi11 months ago
I think you can use step down regulator with L200 with external transistor. huge power supply need if you load high current
zacker1 year 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!
zacker1 year ago
wow...came out very nice!
newtonn2 (author)  zacker1 year ago
Thank you very much!
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, http://www.instructables.com/id/Converting-a-computer-ATX-power-supply-to-a-really/
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:
http://diyaudioprojects.com/Technical/Voltage-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?

Thanks.
mobilohm1 year ago
Hello
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 Jameco.com 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 it..so 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 things..so 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!
lancellot072 years ago
additional question: when i used +12v and -12v using lm350 as regulator, why do i get 12v as an output, following your schematic..
lancellot072 years ago
how much is the max amperage of your power supply?
yoyology2 years 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?
BenchPSU.jpeg
newtonn2 (author)  yoyology2 years 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...   :(

Here
 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...

http://www.ebay.com/itm/3-DC-5A-Blue-LCD-Digital-AMP-Panel-Meter-Ammeter-/250599164625?pt=LH_DefaultDomain_0&hash=item3a58dfcad1#ht_3369wt_918

http://www.ebay.com/itm/3-DC-20V-Blue-LCD-Digital-Volt-Panel-Meter-Voltmeter-/260571455891?pt=LH_DefaultDomain_0&hash=item3cab44e193

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
Ok thanks but also I might not use wood . The system would be more compact with meters that are powered from the psu.

Do you have any ideas?

If not Ill use your links so thanks again brother.
tgtomm4 years ago
Rather than using batteries and switches and such for the panel meters, you can use some dc-dc modules with isolated outputs. This sounds complicated but it really isn't.

I have just done this and put together a detailed guide on doing it over on my wordpress blog here.

Hope you find it useful.
I thought about dc-dc modules with isolated output is the only way. Glad you point it out.. Check ebay and they(Hongkong suppliers) have digital ammeters and voltmeters that can be powered directly from the "measured" circuit..
Could you or Newton show a link please?
gr8_viruz4 years ago
"I can use ether -12v or 0v (ground), the reason I've done this is because the -12v is not as powerful as the 0v output. So with setting 1) I can go from 1.2V to 23V but is limited to 2A, and with setting 2) I can go from 1.2v to 11V up to 3A"

Is there a way to get 3A for the first option?
that it can make max 24V and 3A output.
I think you could wire two atx power supples in parallel with diodes!
Never connect them in parallel it can be a mess cause it can generate an overload... for 24V u can connect them in series that is safer but is difficult :D
newtonn2 (author)  gr8_viruz4 years ago
 
I don't really know if is possible from the 24v output really. If you need a really powerful 24v power supply I would suggest to make one with an AC transformer.
ASG_83 years ago
Great Instructable!! :)

Can the 2 5k potenciometers replaced by 1 potenciometer of 10k?

Or could I put a 5k potenciometer and then another one of 1K or even less to have a more precise control of voltage?

Thanks!

Hi,
Thanks it is very good instructable and exaxt thing I needed.I used a cheap multimeter and switch it on with a relay. And I used two 5W 12V bulbs in 5V circuit instead of power resistor.  So here are my pics:

01.jpg00.jpg02.jpg03.jpg
newtonn2 (author)  asdasd1231233 years ago
Thank you very much for sending the pictures. They are the first pictures I see of someone that did something similar to my instructable. The bulbs light the inside, that cool!

Well done mate!
Here are some photos of my finished voltage regulator with a printed and developed PCB and the finished board
Finished Regulator PCB.jpgFinished Voltage Regulator.jpg
That power supply is the same one I am currently using on my old power supply..it does fine, in my Newtonn2 Power supply I am going to put two PSU in the cabinet and also fix it with two regulators and also affix the second PSU with pre set resistors, I do alot with LED's so then that will give me a fast connect on the power I use the most, and give the addition of the Newtonn2 design as well..
Ohh, and I had a brass name tag made for it that states "Newtonn2" on it so you now have a bench top with the credit to you for the design out there..thanks again
newtonn2 (author)  paradise974023 years ago
That's cool I would love to see it once it's finish!
Newtonn2, Sorry for takign so long, but been busy lately. btu I started gettin gthings together in th ecase, I decided to take th eATX out of th ehousing and mount it to some aluminum rails..
2011-03-09 11.07.45.jpg2011-02-22 09.30.26.jpg2011-02-22 09.30.37.jpg2011-02-22 10.25.19.jpg2011-03-09 11.21.46.jpg2011-03-09 11.22.02.jpg2011-03-09 11.22.13.jpg2011-03-09 11.22.35.jpg
newtonn2 (author)  paradise974023 years ago
That looks very good. Well done. Did you try your circuit already? does it works fine?
Newtonn, Yes, the circuit works great..I went ahead and ordered some new meters..after looking at your back lit..I am goign to change them to ones like yours, but I am going to build another circuit to run on the second power supply, so I am goign to have to change the front to hold the extra parts on it. but I am also goign to take and put two regulators onto one PCB and this time I am going to go ahead and put the design onto a clear sheet develop it onto a sensitised board. but I will send you a copy of that one as well.
but with all the fans it is like a cyclone in there so ther should be no problem with anythign getting warm in there.
Newtton2 here is the board layout for the power regulator, this is the layout and drill guide.
the thing im not sure about is the third lead on the 5K pot.
I followed the schematic exactly and have done so many times and every time it only goes to 1.3V max. I think its the voltage regulator because when I switched the LM350 with a IRF9432 it went to 24V with the same pin configuration but when i put it under load it sends the voltage to zero (it decided not to work anymore so theres no reason to take pictures) and usually burns out my potentiometers, I've lost at least three pots because of overpower and I'm wondering why yours are fine. I was thinking about just buying more LM350's, do you have any advice before I potentially spend my money on something I don't need?
DSCN1030.JPG
newtonn2 (author)  Jimmy Proton3 years ago
I'm so sorry. I hope my I did the schematic right. No one told me yet otherwise. Did you try to do the simple schematic? You can check this one http://www.instructables.com/id/How-to-Build-a-Bench-Top-Power-Supply/

I will double check the schematic later.
So I would just use the schematic you sent me and use it in the bigger circuit and thanks.
I tried the new schematic and I only got .7Vout so it must me the regulator, I may have damaged it when I soldered it because I remember it getting very hot when I soldered it.
Can I use an LM320 instead of an LM350?
moeakram3 years ago
Hey I'm trying to make your power supply and I got my hands on a recycled 500 watt atx and I was wondering how would that affect the design??
Ok, well as I go trough my order I noticed that the Capacitors I got were both Radial types..and the only ceramic I have is a .1uf 100v will that work?
newtonn2 (author)  paradise974023 years ago

Hi there! I'm glad you like my bench power supply. I can say that I've been using this power supply for more than a year without any problems.

I'm sure you could use that capacitor, it should be fine. If you need any help, let me know.

Regards
Newtonn2
Hey one more thing..the relayI wasnt sure if it should be a 6v 5amp or a 10 amp so I ordered both..but what one do you suggest?
newtonn2 (author)  paradise974023 years ago
Any relay will work. The relay it's only to connect the battery that power the Voltmeter, so you could use the 5amp if you want. It may be smaller than the 10 amp.
welder guy3 years ago
THERE IS NO NEED FOR THE 10 OHM RESISTOR! ive built at least 10 of there power supplies, taugh my friend how to build these power supplies, and used then for 3 years now. there is no need for it. all it does is waste power. the PSU'S STILL RUN WITHOUT IT!
newtonn2 (author)  welder guy3 years ago
THANK YOU VERY MUCH. If You read the instructable you'll see that I don't see any difference. I build a few and never use the resistor ether. But I read that some PSU needs them. So that is why I fitted one.
owenaero3 years ago
great build i am thinking on doing one similar to this i do highly suggest using a shunt with your amp meter for safety.
newtonn2 (author)  owenaero3 years ago
Hi there. Thank you. What is a shunt? what is for?
tgtomm newtonn23 years ago
If you have the same ammeters as me (i think you do) then the shunt is built into the ammeter. If you look at the back of the ammeter you will see a wire (around 2cm long) on the board (somewhere near the connectors). This is the shunt for these meters.
newtonn2 (author)  tgtomm3 years ago
That's right. Mine has that on the back. Thanks
An ammeter shunt allows the measurement of current values too large to be directly measured by a particular ammeter. In this case the shunt, a manganin resistor of accurately known resistance, is placed in series with the load so that all of the current to be measured will flow through it. The voltage drop across the shunt is proportional to the current flowing through it and since its resistance is known, a millivoltmeter connected across the shunt can be scaled to directly display the current value. i will get you w wiring of a shunt asap my scanner is down
here you go found a image
High_side_current_shunt.JPG
newtonn2 (author)  owenaero3 years ago
Thank you very much!
Elias_923 years ago
What's the measure of the box?
waterplanet3 years ago
fantastico el trabajo
newtonn2 (author)  waterplanet3 years ago
~Muchas gracias~
diyman3 years ago
nice job on schematics and the project itself. i've been looking fo something like this for a very long time. i have a question and that is, would it be okay to just connect a multimeter instead of a volt (or amp) panel meter.
where the potentiometers are, do you hook them together or are they separate?
and can you just use a DPDT switch for the meters instead of the relay?
juggler734 years ago
hi 
i wanna build this power supply but im having a problem understanding the relay part. the 12v and ground go to the diode then the relay and thats where im stuck, is it connected then to the switch then the 9v battery then the volt meter. dont understand that bit of the schematic

great power supply btw
you don't need to use the relay switch, you can just use a regular switch like the amp meter.
godofal4 years ago
wow, and these things can cost hundreds of dollars, and u can make one with 50 bucks max :D
if i find the time sometime, il make this, its great!
newtonn2 (author)  godofal4 years ago
Thank you!, I have to say that my bench power supply is not as good as those that cost hundreds of dollars, but for my use it's perfect. Go ahead and make one, as you can see it is worthy for the money.
most ppl that have elektronics as a hobby dont need super sofisticated stuff, unless ur planning on making a rocket anytime soone, this should suffice :D
and thats  the beauty of it :)

when i was writing my last reply, i thought id had to find some ATX, but i realised later i have a frigin old PC lying around somewhere :D

anyway, biggest problem now is finding a hot glue gun >.< the ones i get always break, or couse shortage, or something else.

wouldnt be surprised if the next one would set this project on fire XD
3stepps godofal4 years ago
 Back in the 80s when I was working at a company that made satellite receivers we had to do some mods to a board that was missing some power and ground traces. Instead of buying hot glue guns they just issued an old soldering iron and we melted the glue by holding the glue stick to the side of the iron. That worked as long as we didn't need a third hand to hold something in place. It's not an exact placement of the glue, sort of winds up as a blob but it is a quick and dirty fix.
godofal 3stepps4 years ago
i know, i just do it a bit different couse i dont wanna mess up my soldering iron, i take some needlenozed pliers, and hold a tinned screw  (or anything make out of metal) to the iron, then u can use that to melt the glue, and then using a second (long!) screw, u can aply the molten hot glue...
Hycro godofal4 years ago
I use my soldering gun, and I don't worry about messing up the tip, 'cause it's a home made tip, 'cause you can't get tips for mine anymore...heck...I haven't even seen anything like it anywheres. I did have a second soldering gun, a 100W model, but, the main coil burnt out in it, but my old Simpsons-Sears 240/325 Watt soldering gun is still going strong, despite the fact that it no longer has the dual spotlights on it, although, I could probably fix that up with just putting new bulbs in it...lol...
I built a smaller one and use it all the time, I even added one to my breadboard.
newtonn2 (author)  scratchr4 years ago
 Good Job! I like your power supply. It looks vintage.
Hycro newtonn24 years ago
I have an old power supply that uses a selenium rectifier (with 1940, 1947 copyright years printed on it), has what I think is 18-gauge enamelled wire, on two large transformers, has one huge physical sized capacitor in it (don't know the rating) the fuse is 30A, uses wing-nut binding posts (12V only), and all soldering on it appears to be done with a propane torch, as my 325W soldering gun cannot get hot enough to even begin to melt the surface of the solder, the original toggle switch was dead when I got it, so was the power cord and indicator lap, so I replaced the switch with a newer one, still the same style, and the power cord I replaced with one for a computer PSU. The indicator lamp, I think I put a regular 12V automotive indicator lamp in place of the bulb, I have also added a couple electrolytic capacitors underneath, an automotive voltmeter on the front (bolted to the transformer bolts, which are what hold these transformers' plates together) placed some cardboard between the plates of the rectifier, to prevent shorting, and added an earth grounding post onto the back. I have no idea where the cover for it went though...oh, and I also fixed up the fuse holder so it can be opened easier, the original d-ring appears to have broken off, taking some of the protrusion of the fuse holder with it, making it very hard to grip the end to remove the fuse.
thanks!, this is my smallest:
2010-03-26-171154.jpg
newtonn2 (author)  scratchr4 years ago
 That's cool, but the problem I see here is if you use the LM317 to regulate the voltage and use a battery you facing a big drop of voltage like 6V or less. What do you use this for?
I use it as a compact breadboard power supply and motor driver.
newtonn2 (author)  scratchr4 years ago
 I made a few power supply. Here is the smaller one I made, it has a monitor power supply inside, so it connects straight to mains. It needs a multimeter to check the voltage tho. 
SANY0487.JPGpowersupply.png
Mrfixit56444 years ago
All I can say is Awesome, I'm a Renewable energy major and I'm working on getting my bench put together to work at home. I have looked at many different power supply ideas and sets of directions. This one is heads and shoulders above all the ones I've looked at. I especially like how you didn't buy everything new. I can't wait until my break between terms in school to build it. Thank you very much for sharing. :D
nice job on the schematics
newtonn2 (author)  Jimmy Proton4 years ago
Thanks!
tgtomm4 years ago
I imagine the meters couple their -ve supply with the -ve side of their measurement. This could be how you broke one (since you would be using 0v as -ve supply and -12v as -ve measurement). This should be easy to check with a multimeter and then you could try powering the meters between -12v and ground (perhaps adding a voltage regulator) I'm no electronics expert but i do know cheap meters can often be broken this way
tgtomm tgtomm4 years ago
Scrap that. just received some similar meters from ebay. Looks like they need completely isolated supplies. I'm going to order some of these: http://uk.farnell.com/jsp/search/productdetail.jsp?sku=8727554&CMP=LEC-XPPowerSC&ATT=8727554
hamstanz4 years ago
What market do you goto ?
sayem7074 years ago
Great job bro ..... I am sure I'll try this one :D
Adri3l4 years ago
This may be a rather silly question, but here goes. I just found a datasheet of the LM138/LM338 5-amp adjustable regulators from national semiconductor. Would either one of them be a good replacement for LM350 rated for 3-amp, say if someone would like to draw more power from the PSU on the 0-12 line?  
newtonn2 (author)  Adri3l4 years ago
You could use it to get even more power out of the bench power supply. It may need more cooling tho.
Adri3l newtonn24 years ago
I already use a Pentium 1 CPU radiator+cooler on my lm317-t and it's always cold to the touch, even if I leave the power supply at 1.25v or full voltage for a very long time. I asked this, in the first place, so i could be sure to recommend it as a good replacement for people who can't find lm350 regulators to buy anywhere near them(like me). Thanks for the info.
jonesy434 years ago
Also Since I have the 6V Relay if I wire it to the +5Vout will that still work with every thing else or does it need to be +12Vout?
newtonn2 (author)  jonesy434 years ago
Hi there! The schematic is wrong, sorry. I did use a 6v relay connected to the 5V output. But there is not difference, you could use a 12v relay connected to the 12v.
Thanks for the info. I'm really just a beginner in electronics and think this instructable is awesome! So I am following your instructable very closely and not trying to change things. So other than the relay everything else in the schematic is correct? Thanks again and I'll let you know how things turn out in the end.
newtonn2 (author)  jonesy434 years ago
No problem. I don't now much about electronics ether, but internet is a good source of info. I think the rest of the schematic is fine. If you have any question or anything, just let me know.
jonesy434 years ago
Great Instructable! I like it so much that I am trying to reproduce it. Your list of Items says a 6V Relay but your Schematic has a 12V Relay and you are running your wire to the +12Vout. Did you mean 12V relay in your list instead of the 6V Relay?
Adri3l4 years ago
First of all I would like to congratulate you on your bench supply and for this instructable...They are both great work. But the reason for this comment is to ask if LM350 is a variable voltage regulator, while the LM317 is a variable positive voltage regulator? Because where I live I am unable to procure a LM350 integrated circuit, I barely found the LM317 after 2 weeks of intensive searches.So I followed the instructable you linked to for the lm317 and if I connect the + terminal to +12v(yellow) and the - terminal to -12v(blue) i get a maximum of 11v out of the regulator. Any ideas on the matter would be greatly apreciated, thanks.
newtonn2 (author)  Adri3l4 years ago
 The LM317 and LM350 are positive voltage regulators. They works the same. The differences is that the LM317 is rated 1.5A, and the LM350 is rated 3A.

How are you wiring the regulator?  Are You sure they are connected where they go.

PS: Sorry for late answer.
Adri3l newtonn24 years ago
I have tryed exactly the same wiring like you, but the LM317 would not start, the voltmeter always showed 1v(wich is bellow 1.25v)  nomatter how much i turned the pot left or right. So I used the design that you inspired from www.instructables.com/id/How-to-Build-a-Bench-Top-Power-Supply/ and it works when I put the + of the regulator on the +12v line and the - of the regulator on the 0v line (i can adjust between 1.25 and about 10.80v).But if I put +12v on the positive terminal of the regulator and -12v on the negative terminal i get only 1v more on the outcome( between 1.25 and almost 12v).

Funny thing though, I accidentaly reversed the regulator once when I was testing, i put the + terminal to -12v and the - terminal to +12v. The voltmeter said that i was running -1v at the outputs, and after about 20 seconds the  10uf electrolytic capacitor exploded and i found pieces from it in about a 3m radius
profpat4 years ago
 i would like to commend you on very nice project, i did this too using an old AT PSU and then another one using ATX one, but i never though of in-casing them in a box, i mounted all the binding post on the atx steel casing..

suggestion: since the highest voltage we get is only 12 volts, you may use old adapter  for HP 600 and 800 series printers, they give out 30 Volts of 500ma..for more amperes, use 2 in parallel, or, you may use adapter for laptops, usually they are rated at 19 volts 3 amps - up..


newtonn2 (author)  profpat4 years ago
 Hi there! I'm glad you like my bench power supply.  

 I get almost 24Volts out of this power supply, but about 2A.  I've done another power supply with one of those power adaptors. Good idea. Thanks
electricfan4 years ago
isn't a 2 way switch and a on/off switch the same?
newtonn2 (author)  electricfan4 years ago

The 2 way switch will allow you to switch between two cables, like 0v and -12v, so in position one the 0v will be connected with common, and in position two the -12v will be connected to common instead of the 0v.  I hope you do understand what a 2 way switch is. 

I get that, what I saying was that you can make a 2 way switch with a on/off switch with a little soldering.
newtonn2 (author)  electricfan4 years ago
 Yeah? you explain to me how is that done please.
LOL... And there was silence...
juggler734 years ago
hi
also what type of switch is used for the regulator switch

is it a   double pole double throw, single pole double throw?

thanks
Kirbsome!4 years ago
Hehe, tried starting a mini ATX now, but I used a small resistor.
It started alright, but the resistor was glowing and now my room smells gross.
newtonn2 (author)  Kirbsome!4 years ago
 LOL! You need to find a wirewound resistor.
Yeah, read that, just couldn't find one at the moment.

(also, +5 is the yellow wires right?)
newtonn2 (author)  Kirbsome!4 years ago
 Yes.
Check your powersupply's label, it will tell you what color goes where.

Yellow is normally the +12vdc rail, not the +5vdc rail, which would explain why your resistor turned into a lightbulb.

5vdc is normally the red wires.

I've got an ATX bench supply, which, luckily, if there isn't enough load, it won't start instead of going "zzzt pooof!". I give it its load with an old hard drive :) not much current, but its enough to start it.
you could convert the hdd platters into a case fan for the psu so it provides the required current and the cooling needed :)
Further to my message :)

As with the load resistor, normally power supplies have a minimum current on EACH rail.

Check the sticker and the manufactorer's docs!

For example (even though I don't use this particular PSU as a benchie)
My ThermalTake 430 PSU has the following min currents (note its 430w rating is PEAK not constant)

3.3v - 0.5A
5v - 0.3A
12V1 (12v rail #1) - 1A
12V2 (12v rail #2) - 1A
-12V - 0A
+5Vsb (always on 5v) - 0A

Here are its max currents:
3.3v - 20.0A (66 watts)
5v - 12.0A (60 watts)
12v1 - 20.0A (240 watts)
12v2 - 20.0A (240 watts)
-12v - 0.3A (3.6 watts)
+5Vsb -2.0A (10 watts)

Note how v1 and v2 have a total of 480 watts?
on the sticker is a little fine print saying
"Total combined 12v power must not exceed 23A" (276 watts)
That's a maximum 240 watts on either/or 12 rail, not both together.
You can't get more power out than you have going in - that would be perpetual motion which cannot exist in a power supply because some of the input power is dissipated as heat. That's why there's a fan inside!

~Lee
An old CD ROM drive will do the same trick without adding all the extra noise. Then, as an added bonus, hook either the analog outputs at the rear of the drive or the mini phone out on front to a stereo and you now have music for your work area. (Make sure you use a drive which has minimum two buttons on the front - Eject and Play/Pause. Some of the old 2x and 4x drives even have Skip F and R.)

~Lee
 Lee, I just want to make sure I understand what you are suggesting. I am not entirely clear on the issue, so I'll say what I think and then you can tell me if I am wrong.

From what I have read in newtonn2's instructible, it looks like the 10W resistor is being used between the 5V rail and ground to fulfill a minimum current requirement. According to the comments here, this is a bad way to do things because it is a massive waste of power; I can see that myself, since that would pump curring straight from the source to ground with very little resistance between.

Looking at mbainrot's post from Dec 28th, it appears as though there is a minimum current requirement on each rail, so merely putting a resistor on the 5V rail is not sufficient. If I am interpreting your comment correctly (Lee), it seems like you are saying that attaching a CD ROM drive (via molex, I am assuming) will satisfy all of the minimum current requirements. Do I understand correctly? Would it be better to follow amarquez's solution with a tail light/turn signal?
Actually Muftobration, each leg of the power supply should be loaded (probably a 1K ohm or maybe a 500 ohm), but I have never had any problems using my method. The main reason for loading at least one of the outputs is that (unloaded) the voltage can actually exceed the voltage ratings on the internal filter capacitors. When that overvoltage condition occurs, usually the filters go (POOF) or (BANG) and tend to stink up the room.
The tail/turn signal lamp still uses a lot of current, and if you're going that route those bulbs don't last forever...
The old CD ROM drive serves two functions at once - load for the PS and music source. Plus, I have a stack of old CD drives nearly as tall as I am. Also you can find CD drives at yard sales for as little as 25 cents. B)
 Thank you for clearing that up, Lee. I had a tower in my basement with two CD drives and a DVD drive, so I just snatched one of the CD drives. I am not particularly fond of changing light bulbs, so I think this is the best way.
Any time, neighbor.
~/Lee
scratchr4 years ago
Hot glue, so useful!
eldorel4 years ago
A lot of newer power supplies have a 120mm fan mounted onto the bottom of the unit, pulling air in at the bottom.

The older ones have 80mm fans on the back, pushing the air out.

The way this unit is mounted a newer supply won't have enough pressure to force the air out of the case.

For other people replication this project, it might be a good idea to mount the psu, or the extra fan, over the vent on top of the unit to force the hot air out.


godofal4 years ago
why do those meter panels not work without those batteries? is there any way to make them work with the ATX??
newtonn2 (author)  godofal4 years ago
 
There mast be a way, but i could not power then from the atx. thery would light on, but it will not read amps or volts.
maybe becouse its reading the same power as its powered from?

and what about installing a normal transformer like the ones u use for ur cell phone and stuff like that? add that to the main power switch or something?

its not like the screens will get destroyed becouse there are to much amps running trough it right? (like with a led)
newtonn2 (author)  godofal4 years ago
 That will works just fine
Awesome this is my favorite atx power supply yet. 
newtonn2 (author)  rocketman2214 years ago
 Thank you, I'm glad everybody like it!
 This is a great design I esp like the plug and play aspect of it. But just a reminder to everyone that you don't have to use an old breadbox. Anything that the ATX power supply and the connections can fit in will work also. Have reused cases for all kinds of test equipment before. When I found the metal duct tape I know longer had to rivet a sheet metal plate over it again. That only works if it isn't moved around a lot.  Best one that I have ever seen was where one guy took his PC and remounted in into an old Technics stereo receiver. He said that the PC in the old brown case just didn't fit into his idea of how things should look.
godofal4 years ago
(removed by author or community request)
newtonn2 (author)  godofal4 years ago
 
Ok, Lets put things clear! When you say "this sucks", are you saying that my project sucks? Just because you delivery is taking longer than expected?

Taking into consideration that you bought the panels from different sellers that I did (check links), I have to say that buying from HK Is cheap but the downside is that sometimes take forever. 

In any case this is not something to post in the instructables as is your personal situation with ebay or the sellers. Nothing to do with this instructable.



i mean the situation with ebay, not your project, i think its great (otherwise i wouldnt be building it)
anyway, if u want, il delete the post...
and i did buy one of the two from the same buyer (daifengsu) and the other from someone else, but everything looks like its the same person with multiple accs (ie; same time of absent, same shop, etc.)
newtonn2 (author)  godofal4 years ago
 Ok! That's not problem.  I do understand how frustrating can be when you waiting for something to came from HK. First time I bought the panels meters took about 15 days to come. Then I broke one of them, order another one and after 35 days I did get my money back because I did not received. Then I order another one that took about 20 days to come. So I was like you... all mad!!!
  
yeah well, its not the waiting, im used to waiting for everything, its just that paypal does that refund for 45 days, and both sellers (wich im pretty sure are the same person) are both not on till exactly that 45th day.
so i get the feeling hes just not sending anything, and tries to get my money this way...
newtonn2 (author)  godofal4 years ago
 In any case if you place a dispute on Paypal you should received your money. Did you check the sellers feedbacks? 
yeah, theyr all positive, but it looks like he just made a whole lot of accs to make nice feedbacks (i.e, A+++++ would buy again and again and again)
godofal godofal4 years ago
well, i got the packages in today, so no problems there anymore :D

i do find out every time i order anything over the net that when i hold it in my hands, it seems alot smaller than i imagined it to be (ie, i thought those screens would be about the size off my hand, but theyr actually more like the size of my fingers combined...)

anyway, im gonna test them asap, and then when i have the time il build this great device.
godofal godofal4 years ago
btw, one of the sellers is daifensu, the other is advancedshop.
anyone ever had any problems with them?
zoombeh4 years ago
you could install the psu so that the back (where the fan and mains plug is) is pointing out of the top or back of the box, that would save you a lot of trouble.
Yo. Very nice project.
I would make two suggestions, however:
First, install the PSU into the cabinet just like it was in the computer. The extra power jack and fan grille/ducting are just needless extra work.
Second, I would never use that type of speaker connectors for power. Too many of those are crap which will just add headaches. I would suggest banana jacks. Then your output leads can all be dual banana plugs. Keeps it simple...
One other note: make sure that pass transistor has plenty of heatsink and ventilation. 10 degrees C represents half of the transistor's life.
My overall rating: 8/10
BTW, I have been in electronics repair and engineering for over 30 years. I have designed and built over 200 personal projects not to mention commercial stuff. Had I built this one, I would have been very proud.
newtonn2 (author)  Lee Wilkerson4 years ago
 Thank you! 

I thought putting the PSU as it goes on the PC but there was not enuf space with all the cables coming out of the back.

The speaker connector is really good, I connected a round terminal at the end of the cable so it connects very good.

But with all that experience you have... I really have to take into consideration anything you suggest.  Thank you for your comments.
Yes, you could have gotten good ones, but what about the person who's trying to copy your project and ends up with a set which are absolute crap. I have seen jack sets of that type which couldn't handle more that .5 - 2 amps. A faulty connection there could at very least melt the plastic and could shock supply components into oblivion via current surge. I always design my power supplies to do at least 200% of anticipated maximum load. I have yet to see a pair of those speaker connectors handle 50 or even 20 Amps. Better safe than sorry, my friend. Part of the fun of making instructables is repeatability. Always design for absolute worst-case.
~Lee
newtonn2 (author)  Lee Wilkerson4 years ago
 Of course!  you're right. I thought you were talking about the round type of speaker connector, which I think are able to handle more amps. But I forgot about the other type of speaker connector that I'm using for the constant output. There are not powerful at all.

Is really good idea to go for 200% anticipated maximum load for your power supply, I'm sure you don't have many problems with them.

By the way.. Thank you so much for you advice!
 
newtonn2,

You're welcome. Anytime I can help, I will be more than happy to.

I've never had one of my power supplies fail. Built one once that melted the insulation off an internal wire (10 gauge) during assembly when I connected it wrong, but the transformer (hand-wound) and rectifiers survived. I hate having anything I've built fail...

Best wishes on all your future projects, my friend. B)

~/Lee
newtonn2 (author)  Lee Wilkerson4 years ago
 Hi there! I'm trying to power a few things with a laptop charger rated 20v 3.5A. I need to power a LCD 12V (0.10a), Sound system 12V (1.5A), Fan 5V(0.12), LED 16V (1.7A). I'm using...

-A 12v Fixed voltage regulator for the lcd and sound system
-A 5v Fixed voltage regulator for the fan.
-A LM350 to power the LED. 

The 12v Regulator and the LM350 are getting too hot. I solve the problem placing the LM350 in a big heat sink. But the 12v fixed power regulator is getting just too hot, I think is because of the load. What do you suggest? should I use another LM350 instead of the 12v fixed voltage regulator witch is rated 2A?

Thank you very much!
Hi Newtonn2,
Sorry I didn't get back to you sooner.
Down to business:
The 12V regulator is dissipating:
20V - 12V = 8V
8V x 1.5A = 12W
...therefore you need a heatsink capable of dissipating 12W. That will be a rather large heatsink. I hope you are also using some kind of thermal grease to couple as much heat as possible away from the reg. One suggestion: you could always use an old PSU fan to help dissipate the heat.
Even if you used a 370, you will still be dissipating the same amount of power, although the 370 has a higher current rating (remember my previous comment about 200% overkill). You might also consider a current sharing design with a heatsink-mounted 2N3055 or MJ2955. In most of these designs, the reg. does about 10% and the pass transistor does the other 90%. (Transistors cost less than the regulator...)
I'm not sure where you can find a schematic, although I would start in your local library's reference or periodicals section. You might also look on the semiconductor manufacturers' websites (e.g. National Semiconductors, Delco, and Texas Instruments). I had several schematics for this, but I don't think I have them anymore. I will also be trying to find one for you.

au revoir,
~/Lee
Notch the top and reroute your cables upward. B)
newtonn2 (author)  Lee Wilkerson4 years ago
 That's an idea, but the goal of this project is to be able to change the PSU as easy as possible, so maybe that will add some work next time i need to change the PSU
I dont do the comment-post thing either, but this project is worthy of the exception. I am a 'puter tech n I toyed with something like this a few years ago, but never did anything serious with it. I am also a pack-rat. My parents were the King and Queen of Pack Rats. I will spare you the details. My paternal Grandmother was the Queen Mother of Pack Rats - they filled a 30-yard dumpster 3 times with stuff that wasn't worth recycling after she passed. I have puter pieces-parts and other treasures all over the place.

This project is out n out awesome. And I am da(ng) hard to impress. I will be building me one of these. Hmm - wonder if any of my Cub Scouts wanna get in on the fun?

Your project also inspired me - I think I will resurrect another idea I had and give it life.  You put together a professional-worthy box. If I can do something as good looking as this, maybe I can make a couple bucks selling them whilst looking for gainful employment.

Oustanding, man. Thank you.
old Scouter- new tricks
vickyadrian4 years ago
Waw... That's cool.......
(removed by author or community request)
 Thank you!
mcastles4 years ago
Hey newtonn,

Nice job, I like the idea about the easy installation and replacement of the PSU. That definitely makes it easier if the PSU ever happens to go out, simply just take it out and put a new one in attach to wires then close it. Nice!!
newtonn2 (author)  mcastles4 years ago
 Thank you very much. I'm almost done with another projector I'm making. I'll post you as soon as I finish.
aroff4 years ago
Thank You Man
WONDERFUL THANK YOU
CoolKoon4 years ago
It's a nice 'ible you've got here! Just a few comments and suggestions:
- Try to use PNG/GIF for the schematics instead of JPEG. The latter is not really suitable for high-contrast images (such as schematics, line drawings etc.), since it kinda messes them up and even the resulting file is bigger (such images compress well with GIF and PNG)
- I've wanted to ask you about the 9V batteries in the schematic, but then I've noticed that you've explained it later on. However AFAICT 9V batteries don't last long and since it's a power supply it's a bit awkward to have them powered from battery (especially two of them). Your PSU has killed them probably due to overvoltage (12V resp. 10V vs. the 9V they need) which can be mitigated by inserting a resistor in series with the meters (google for "voltage divider calculator" for help getting your correct value) or using a 9V power regulator. Installing a separate transformer is also an option (though infeasible for two meters as they don't consume much). BTW those meters of yours are not analogue ones. Real analogue meters look like this. Still it's quite a nice project to transform a switching power supply into an universal one (though useless to power audio amplifiers, but you can't always get what you want :P). Good job! ;)
Better to just use a 9v regulator or variable regulator set to 9. As you light more segments on displays, they consume more power.
~Lee
And would the voltage drop be so significant that it would justify using a regulator and risk having the cost of manufacture increase by $0.5 or even $1?! That's $1000 for 1000 units of this! A LOT of money! Nah, just kidding :)
CoolKoon,

Your sarcasm is exemplary.

~/Lee That's 'homelee' for Linux fans.
Maybe it's just your sense of humor that's lacking. But anyway, won't you please stop trolling?
Nah, I have an awesome sense of humor. Sometimes I even crack myself up!

Furthermore, I'm offering excellent advice based on 3 decades of repairs and engineering in both electronics and computers. If you don't want good advice, cover your eyes.

~/Lee

Hmmm, probably it's me who's lacking any sense of humor. Maybe it was just me, but I really mistaked your signature as a label for my sarcasm (homely)...... Sorry for that, if you didn't mean to.
CoolKoon,

No, that's just me (home-lee or sarcastic-lee or a-parent-lee). No offense was intended, but I know people misunderstand what I mean sometimes (even my closest friends).

Meanwhile, anything I can do to help, I will do. If you would like for me to regale you with tales of some of my projects, that I can also do.

I also offer free advice on any kind of electronic or computer project.

~/Lee
newtonn2 (author)  CoolKoon4 years ago
 Thank you for the detail review of my instructable, I'll fix the mistakes.

The JPG looks great, but you have to see it big. A schematic that big won't be any good in PNG if you have it small. I'll try next time on PNG.

-The "DIGITAL" meters (I'm sorry, I don't know why I called them analogue meters) works at 12v. The problem was that they works but they where unable to read.

Thank you again for your review.
I did view the big one too, but my point is JPEG is ineffective for schematics sizewise and quality-wise as well. I woldn't have been able to point out the 9V battery thing on the small schamtics picture either :P
Those meters still seem to be a complete mystery for me. I've looked up its specs and it says it works with voltages in the 9-12V range. But if they were designed to work at 12 volts as well (hence it wasn't overvoltage that has killed them), then possibly the switched current coming from the source might be the problem. Adding a few high-capacity caps in parallel might fix this problem. But a single 9 or 12V transformer might work as well (according to the meter's specs you don't have to rectify the current even) so that you won't risk blowing up those meters again.
I wonder if you are having a supply isolation issue here...
Yes, I think you are.
Hell, just wire in a 9v wallwart. :)
andreblue4 years ago
for the usb you could have taken some old usb male to female cords and wired them inside and ran the cord out it would give you more flex
tudgeanator4 years ago
Good 'ible, but when i tried to view the pdf schematic it said 'file damaged and could not be repaired'. Is anyone else having this problem, or it just my computer? Is there any other way i can see the schematic any bigger? Cheers.
newtonn2 (author)  tudgeanator4 years ago
 The PDF works for me. You could click on the image of the schematic to see it bigger.
 Thanks, i don't know why i didn't think of just looking at the image bigger, that worked fine.
thermal interface paste would help your wire wound transistor stay cool against that heat sink... i always have a tube of arctic silver ceramique for just said cause.... believe it or not you can buy it from radio shack now...
 If you live near one Harbor Freight tools often sells their junky digital multimeter for around $2 If I am not mistaken it is the same one you have there in the video.

Sure it is not recycling but it is a dang cheap way to embed a Ahmerter/Voltmeter/Ohmeter in your project.

Hycro4 years ago
Lol...at least you bothered to label everything...I would have just left everything unlabelled, and just went by what wires were where. Plus some more "recycled" ideas would be to use the volt/ammeter gauges from a car or truck, and for your molex connectors, remove the ones from the internal drives and solder wires to the leads for those. And I think if I something like this, I'll use an old computer tower, a small one, and cut all my holes in the plastic front panel, that way I'll have ventilation, plus a place to mount the PSU, convenient mains power cable location (the PSU's original socket), plenty of room for the extra wires, and is convenient to access the insides.
Voltmeter from a vehicle, yes. Ammeter from a vehicle, probably not. At the typical current output levels you will be utilizing, an ammeter from a vehicle will have an accuracy of +/- 3 to 5% and (unless it's shunted externally and you can change the shunt) will barely register or at best 1/4 to 1/2 scale.
I have found most of my ammeters at hamfests/hamventions and such. If you're in the U.S., I think there's still one very large one in Dayton, OH at Hara Arena in April every year. If so, not only do they have ammeters there, they have everything imaginable by way of computers and electronics, and some things there even stretch the imagination. People come there from all over the world...
You can get local or world info by Googling 'amateur radio club'. There will also be smaller swap meets closer to your home - most likely within 30 to 50 miles. That's everything at one big stop!
Have fun shopping.

~Lee
Hmm. I guess you do have a point about the ammeter...
newtonn2 (author)  Hycro4 years ago
 Thank you. I thought about using a old pc case, but they are just to big, even if you get a really small one it would be still bigger than the breadbox. 

To use the PSU original socket is "crazy" LOL. I've seen people do that, but is a big job just to save a few bucks.
Hycro newtonn24 years ago
Yea, I suppose you do have a point there.
amarquez4 years ago
I forgot to tell another tip,  the newer computer Power supplies tend to have LESS uotput current capability in the 12 Volt output.  If you want to use the 12 V oulput more than the 5 or 3.3 Volt outputs, try to find an OLDER, heavier unit.

I also have found that many lesser quality units have much hyped, inflated power ratings, like some of you have found, are for momentary loads, and not continuous ones.  but if you need less than ten amperes at 12 V, there are a lot of models "rated" around 350 Watts that can supply 10 amperes or a little more when the 5V output is loaded with both filaments of an automotive stop and turn signal  bulb, as Iposted above.


I agree with mbainrot, the sticker ratings are approximate, and lately manufacturers (mainly from China) are abusing the  true values that the supplies can really deliver.  Only by testing can one find the true  safe limits of them.  But if your  uses demand less than 10 amperes, most of the units are usable with great success!

Good Luck.
aireal4 years ago
Really great job all round mate.
I will certainly be making one of these.
chouf4 years ago
hi, this looks like a very well done project, but why one would need this? I do not see the ultimate purpose of this kind of device. Thanks
Honestly, a proper DC supply is indispensable for lab use. For this one, he could charge a car or motorcycle battery over time.
Yes, 12 volts at 25 amps would almost charge up a car battery except...
These power supplies cannot maintain their rated outputs continuously. Then add to that, a fully charged lead/acid battery's gassing point is 14.4 - 14.8 VDC. If you plan on charging car batteries, you will need a current limiter circuit and you will need to put 2 PSU's in series (the negative lead on one connected to the positive lead on the other) and regulate the output voltage back down to about 15 - 16 VDC. Well you could use the +12 v on one and the +5 on the other. I don't think it's worth the bother...

~Lee
static chouf4 years ago
 
purpose? To supply power to projects or appliances that require a DC power source.  To keep this short.
cre8ev4 years ago
I hate to sound so ignorant but I am. What do you use this power supply for? does it substitute for low voltage? for LED's etc? Please explain.
thanks
Hey i like this one just as much as your first one, i built your first one and i am still using it, but i need more power so im going to attempt this one. One day the internal capacitor exploded which was my fault lol. When you running the displays what voltage do they need to be and whats the amperage? i thought about running the displays from a regulated low amperage adaptor and have the switches on the mains switching side, then do a link from the mains input to the other transformer.
But again nice idea for it.
steve19114 years ago
 Those are not analog meters.
newtonn2 (author)  steve19114 years ago
 Thank you, I changed it already.
 btw, this is a very nice instructable - good job!
whitetiger4 years ago
hi man...

i've got a correction to you, in the pdf with the schematic, you connect the USB connector to the +5(RED) and the 3.3V (orange) instead of GND(black)
be careful with that !!!

tnx
newtonn2 (author)  whitetiger4 years ago
 Oops! Thank you for letting me know. I going to change it right know!
awesome! love it
inchman4 years ago
This is not only a great idea, and a very useful device from scrap, but you document it well and the directions are very easy to follow.

Thanks for posting it!
WB3334 years ago
How about adding current control --  then I can use it for electroplating
jewelry I cast.  

Thanks.... wb333
WB333
How much current do your electroplating jobs need?
This 400w supply at which I am currently looking can only supply 25A at 12V and I'm sure that's not continuous.
static4 years ago
 A good looking final product on your take of a popular project, and your instructable turned well also. You also did a good job of showing how "Junk" box(es) have value.   I would have used a pass transistor(s) on the voltage regulator to be able to handle the maximum 12 V.current the PS could deliver. I would also add a crowbar circuit at the regulator output for over voltage protection. My current PS projects are re-purposing the 12 VDC PS out of commercial grade 2 way radios as stand alone PS.
billbillt4 years ago
This is a first class job. I have been using ATX power supplies for several years for this kind of thing, but not as sophisticated as this. I have used them with and without the 10W resistor and can tell no difference in actual use.It takes longer to take the cover off than build one. Every time I see an old computer out to the curb it comes home for testing for use or parts. The bread box case is a brilliant idea.
tswill24 years ago
Nice job - just a couple of language confusions I'd like to mention - that is not an ATX, it is a recycled powersupply from an ATX computer, and those are LCD Digital meters, not analogue.  Analogue meters have swinging pointers with a (usually) curved scale.  Back in the old days, about the time your Dad was born, experimenters were known to construct circuits by mounting the parts on wooden breadboards, hence the term "breadboarding".  Perhaps this will start a construction method known as "breadboxing"!
tswill2
Thav4 years ago
I'm surprised they broke. What input voltage are they rated for? Did you hook up to +12V? I would guess using another small linear regulator could get you to 9V without too much trouble for those.
newtonn2 (author)  Thav4 years ago
 I tried to connect it to 12v but it wound't read the voltage, it did show an error. So I tried to connect it to the red  and white to get 10v, to see if it would work, but that did damage it.
you could have powered the meters off the 5 volt side. maybe an 8 volt regulator an LM7808 off the 12 volt side to power the meters and that could have been enough to make them read right. Or to get really creative use another variable regulator and adjust to 9 volts not enough amp draw on each meter to cause the regulator to overheat 
fjch1004 years ago
ddavel5444 years ago
I wouldn't know what to do with it...but I do like step #4 that makes it easy to change out the ATX from the enclosure.
trumpy814 years ago
Great project! Love the bread box ... who would have thought of that? and it looks good too.

You could have powered the meters from the ATX supply if you used a bridge rectifier and a 9v regulator, both small inexpensive parts that would eliminate the need to change the battery .... just a thought.
godofal4 years ago
hey, i have a small  problem, i can  only find a 1.0 uF ceramic capacitor, instead of an 1.1 uF.
what should i do, will that 1.0uF work? or can i use a  radial one?
godofal godofal4 years ago
wait, i just thought of something;
with resistors, its so that in serial they add up right? like 100ohm linked to an 50ohm makes 150ohm resistor?
does this work for capacitors to? so i use a 1.0 uF, and link that to a 0.1 uF, and then i get the 1.1uF i need?
to increase capacitor's value you would put them in parallel not series - caps work exactly backwards from resistors - turns out ya may not need 1.1 anyway but a .1 (as per next post)
de SuperPickett
newtonn2 (author)  godofal4 years ago
 Sorry! There is a mistake on the part list. What you need is a 0.1uf ceramic capacitor.
tmealer4 years ago
This has got to be the best instructable on here. I love the use of recycled parts and all the pics of what they came out of. So many good ideas come from information like this. Dude you rock!!!!! Great job. Keep it up.
Dr.Bill4 years ago
I got a 25 amp switching power supply I'm gonna do something like this with it.
Thav4 years ago
If you find this regulator gets too hot, or you need more output power, National Semi makes some "Simple Switcher". Maybe something like this http://www.national.com/pf/LM/LM22673.html . That particular chip has an adjustable current limit, so you could have a current limit like on a commercial bench supply. You would need some external parts, some decoupling caps, output filter cap (you pretty much have these) the set resistors (you have these, +1 for current limit), only 1 diode (probably Maybe 1N5822, 40V 3A schottky) and an inductor (probably small enough to hand wind).
newtonn2 (author)  Thav4 years ago
 That would be really cool! any chance you can provide a schematic! Thank you very much!
Thav newtonn24 years ago
I put this together using National Semi's WEBENCH tool. I haven't really used it before, but I was able to put in design parameters and get a schematic pretty quickly. It does require a registration, however.

I set the input voltage as 12V, the output as 9V @  2A. You would probably put a potentiometer in series with the 1k resistor on the feedback path to make it adjustable. Increasing that 1k resistor would result in a lower output voltage. Without looking at the part in more detail I couldn't say how much or what the low end of the output voltage range is.
Simple Switcher Buck.pdf(612x792) 530 KB
newtonn2 (author)  Thav4 years ago
 Thank you so much! I will definitely give it a try!
wizer4 years ago
Ok, I think it looks really cool.  But what the hell is it?  I mean what do you use it for? 
Jodex wizer4 years ago
Hah great comment! It's a power supply. You can get electricity from it for your prototype projects. And because there's the 3,3 volt out you can test most of your LEDs and with the higher volt outs you can test other stuff like small motors.. And that doesn't only look really cool, because it is!
Looks great! Will have to get round to making my PSU so pimp... Love it! nice work.
 Ok - THE best case design EVER for a power supply, too cool - one word - Awesome!
isacco4 years ago
Looking at the previous comments, I find myself not original, because I also say that this is a great workpiece. Design, crafting, finishing, and Instructable quality are all excellent.
Congratulations!
isacco
B.oom4 years ago
Awesome Example of scavenging, I really need a modulated power supply so i'm definitely going to use your idea as a foundation!!
awesome very professional
Banjomaster4 years ago
Thanks for posting this.  It is awesome!
kissiltur4 years ago
Very pleasing project - almost a steam punk thing going on with the wooden case!

The current measuring device is usually called an ammeter. I don't know why the 'p' is missed out; probably just to make it easier to say.
newtonn2 (author)  kissiltur4 years ago
 
Thank you for letting me know about the ammeter. I'll fix it!
RedMeanie4 years ago
I hardly Ever Post Comments......But This is Outstanding! Very attractive spin to the whole Bench-top Power Supply Phenomenon. Very Good Instructable!
newtonn2 (author)  RedMeanie4 years ago
 Thank you very much! 
NachoMahma4 years ago
.  Fantastic job!
newtonn2 (author)  NachoMahma4 years ago
 Thank you very much!
JakeTobak4 years ago
That is beautiful. I think you're being a little too modest when you say that anyone can do this if you can, but I'll certainly give it a try. I've got a month before school starts, but it's been a while since I've taken any courses in AC/DC circuits, so we'll see what happens :P
newtonn2 (author)  JakeTobak4 years ago
 Thank you. If you decide to make another of this and need some help, just let me know.
lemonie4 years ago
The effort you've put into this is worth it for showing the project, great stuff.

L
newtonn2 (author)  lemonie4 years ago
 Thank you! 
knife1414 years ago
Very nice job on the project, and also a very nice job on the instructable!
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