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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Signing UpStep 1: Materials and tools
The same with tools, you may want to use a different tool, just go ahead, and also make any suggestions so we all can learn.
Don't be scared of the quantity of materials, this project is not really difficult to make, trust me, if I've done it, anybody can.
MATERIALS:
1).- (1)Bread box.( Recycled, you could use any other enclosure that you can fit the ATX in with enough space)
2).-(3) Switches (2 single way switches recycled from old heaters, and a 2 double way switch recycled from an OHP)
3).-Cable connectors (Recycled from old amplifier, and from old TV)
4).-(1) ATX (Recycled from old computer)
5).-(3) PC Drive Molex to SATA Power Adapter (ebay £1.50, view)
6).-(1) 20-24 Pin ATX power adapter for Computer PSU (ebay £2.77, view)
7).-(1) USB connector (Optional, Recycled from old computer)
8).-(2) LED's (red, green) , (Recycled from old computer)
9).-(2) 5K Potentiometer (One Recycled, and the other one bought for £1.35, view)
10).-(2) Potentiometer knobs ( Recycled from old amplifier)
11).-(1) empty can of coke (Recycled)
12).-(1) 8cm computer fan (Recycled from bench power supply mark I)
13).-(1) Magnetic Catch (Bought £1, view)
14).-(1) IEC cable (The cable that connects the computer to the power socket, Recycled)
15).-(1) IEC connector( Recycled from bench power supply mark I)
16).-Piece of trunking (Optional)
17).-Some cable ties.
18).-(1)Fridge magnet ("Stolen" from the fridge)
19).-Some wires. (Recycled from extension lead)
20).-(2) 8cm Fan grills (Recycled from old ATX)
21).-(2) Screw eyes.
ELECTRONICS:
1).-(1) LM350 Adjustable Voltage Regulator (ebay £0.50)
2).-(1) 560 Ohm Resistor (Recycled from old radio)
3).-(2) 1N4001 Diodes (Recycled from old radio)
4).-(1) 0.1 uf Capacitor (Recycled from old radio)
5).-(1) 10 uf Capacitor (Recycled from old radio)
6).-(1) Heat sink (Recycled from old radio)
7).-(1) 10W 10 Ohm Wirewound resistor (Maplin £0.48)
TOTAL COST = £7.60
If you want to use analogue meters like me, and you also want to make the continuity tester, you will also need in addition to the previous list:
1).-(1) Voltage panel meter (Optional £6 ebay, view)
2).-(1) Amp panel meter (Optional, £6 ebay, view)
3).-(1) 6V Mini Relay (Optional, £1.31, view)
4).- (2) 9v PP3 Battery box (£1.29 each, view)
5).-(1) 9v Buzzer (Optional, £1.99, view)
6).- (2) 9V PP3 Batteries
7).-(1) 1N4001 Diodes (Recycled from old radio)
TOTAL COST = £16.59
GRAND TOTAL= £ 24.19
TOOLS:
1)-Drill
2)-Hot glue gun.
3)-Dremel (With a cutting disc and round sander)
4)-Hole saw ( about 7cm)
5)-Epoxy
6)-Sand paper
7)-Solder
8)-A Dymo (Optional, I don't have one, my wife did the labels for me at work, but you could print them and tape them)
note: In this list of materials I specified where I found some of the parts I've used. I'm not saying that you need to buy an OHP or a home heater to get the parts, but maybe you already have some of these things at home and they don't work any more, or you can find then on the street, or in garage sales or in markets like the one you see in the picture below.
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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?
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.
rj_schad pointed some error but I don't see any answer to his comment... so what should one think today?
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.
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.
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!
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?
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.
I'll post pics once I have the whole thing together.
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.
why have a 10W power resistor at 10 ohms that will just be producing heat and using alot more power than needed
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
Do you know what would be best to purchase?
I would be very grateful for you help.
I will shop in meantime.
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
Do you have any ideas?
If not Ill use your links so thanks again brother.
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.
Is there a way to get 3A for the first option?
that it can make max 24V and 3A output.
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.
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: