Another-Benchtop Power Supply From PC Power Supply

8/12/2019 Another-Benchtop Power Supply From PC Power Supply

1/11

http://www.instructables.com/id/Another-Benchtop-Power-Supply-from-PC-Power-Supply/

Home Sign Up! Browse Community Submit

All Art Craft Food Games Green Home Kids Life Music Offbeat Outdoors Pets Photo Ride Science Tech

Another Benchtop Power Supply from PC Power Supplyby LancePenneyon October 29, 2009

Table of Contents

Another Benchtop Power Supply from PC Power Supply ................................................................................

Intro: Another Benchtop Power Supply from PC Power Supply .........................................................................

Step 1: Gather Your Tools and Get Yourself an Old Computer .........................................................................

Step 2: Extract the Power Supply ..............................................................................................

Step 3: Get Out Your Multimeter ...............................................................................................

Step 4: Build an Enclosure...Maybe? ............................................................................................

Step 5: Making the Connections ...............................................................................................

Step 6: Adding the Switch and LED's ............................................................................................

Step 7: Finished! ...........................................................................................................

Related Instructables ........................................................................................................ 1

Comments ................................................................................................................ 1
http://www.instructables.com/member/LancePenney/?utm_source=pdf&utm_campaign=titlehttp://www.instructables.com/tech?utm_source=pdf&utm_campaign=categorieshttp://www.instructables.com/science?utm_source=pdf&utm_campaign=categorieshttp://www.instructables.com/ride?utm_source=pdf&utm_campaign=categorieshttp://www.instructables.com/photography?utm_source=pdf&utm_campaign=categorieshttp://www.instructables.com/pets?utm_source=pdf&utm_campaign=categorieshttp://www.instructables.com/outdoors?utm_source=pdf&utm_campaign=categorieshttp://www.instructables.com/offbeat?utm_source=pdf&utm_campaign=categorieshttp://www.instructables.com/music?utm_source=pdf&utm_campaign=categorieshttp://www.instructables.com/life?utm_source=pdf&utm_campaign=categorieshttp://www.instructables.com/kids?utm_source=pdf&utm_campaign=categorieshttp://www.instructables.com/home?utm_source=pdf&utm_campaign=categorieshttp://www.instructables.com/green?utm_source=pdf&utm_campaign=categorieshttp://www.instructables.com/games?utm_source=pdf&utm_campaign=categorieshttp://www.instructables.com/food?utm_source=pdf&utm_campaign=categorieshttp://www.instructables.com/craft?utm_source=pdf&utm_campaign=categorieshttp://www.instructables.com/art?utm_source=pdf&utm_campaign=categorieshttp://www.instructables.com/about/submit.jsp?utm_source=pdf&utm_campaign=titlehttp://www.instructables.com/community?utm_source=pdf&utm_campaign=titlehttp://www.instructables.com/tag/type-id/?utm_source=pdf&utm_campaign=titlehttp://www.instructables.com/account/gopro?sourcea=inside_pdfhttp://www.instructables.com/?utm_source=pdf&utm_campaign=title


2/11


Author:LancePenney

I am a fourth year university student in the science faculty. My major is Biology with a minor in Biochemistry. I live in St.John's, Newfoundland, Canada. Ihave a very big personal drive to live with zero impact to the environment and I think everyone else should too. Therefore I want to try to develop manyprojects relating to green energy and plant growth.

Intro: Another Benchtop Power Supply from PC Power SupplyThis instructable will show how I built my benchtop power supply from the power supply unit in an old computer. This is a very good project to do for a number ofreasons:

- This thing is very useful for anyone who works with electronics. It supplies nice, clean DC power in a number of voltages with overload and short circuit protection bu

right in!- It is a very easy project. Most of the work is already done for you inside the computer. It's just a matter connecting a few wires and you're done.- It's very cheap. I got the old computer for free and the rest of the parts were under $10. A commercially built benchtop power supply like this could run you more tha$150!- It's somewhat environmentally friendly since your recycling old parts to make something new.

I should mention that this is not an original idea of mine. I learned everything I know about this project from other Instructables about power supplies (there are dozensMy project is unique only because of the enclosure I built for it. The guts are the same as any other one.

My particular unit is capable of suppling +12, +5, +3.3 VDC and -12, -5 VDC. These 5 rails along with the Ground rail can be mixed and matched to provide manydifferent voltages eg. the voltage between the +12 and -12 rails is 24 volts). There is also a handy on/off switch in the front with lights that indicate how the unit isoperating.

Since I don't have any electronics projects on the go yet, I am only able to demonstrate a simple relay circuit. Here you can see the relay powering different combinatiof indicator lights based on the state of the pushbutton.

Image Notes1. The coil in the relay runs at 24VDC so the circuit is made using the +12 and -12 VDC rails.2. The lamps run on 12 VDC so the circuit is made using the +12 VDC and theGND rails
http://member/LancePenney/http://member/LancePenney/


3/11


Image Notes1. The pushbutton switch is open so the coil inside is not energized. Themiddle two lamps are on.

Image Notes1. When the switch is closed, the coil is energized. Contact with the inside twolamps is broken while contact with the outside two are made.2. CLICK!

Step 1:Gather Your Tools and Get Yourself an Old ComputerThe things you'll need for this project vary greatly depending on your own design but you'll definatly need:

- A multimeter- A pair of wire cutters / strippers- A screwdriver with a Phillips head and flat head- An electric drill with a set of drill bits

Other Materials / Tools I used that you might want to consider:

Enclosure:- A sheet of 1/4'' craftboard- Carpener's glue- Clamps of various sizes- Table saw- Carpener's square- Measuring Tape

Electrical Drvices:- An on/off toggle switch- Red 5mm LED- Yellow 5mm LED- 330 Ohm resistors- Solder iron and solder

Connectors and Rails:

- Machine screws- Washers- Hex nuts- Ring terminals- Zip ties

The washers, hex nuts and ring terminals should be sized appropriately to fit the machine screws. The ring terminals should be able to accept 16 to 14 guage wire (thiallows several wires from the power supply to fit in at once).

Finally, you're going to need a computer. I put a wanted ad for old computers in the local online classifieds. A week later I had 3. Or perhaps you already have one lyinaround. A lot of schools will throw away a bunch of computers once in a while too. People should be happy to give them away since it costs them money to dispose ofthem. Either way, when you get your hands on one you'll be ready for the next step.

Step 2:Extract the Power SupplyIt shouldn't bee too hard to remove the outer case of the computer. Usually there is nothing more than a couple of thumb screws holding it on. Once you have removethe fasteners, it should slide right off.

The power supply shouldn't bee too hard to identify either. From the outside of the box, you can tell where it is because of the big fan and the socket into where thecomputer cord plugs in (Photo 1). In most cases there's also a rocker switch near the socket and fan. Once you're inside, you'll also be able to see that the power supis a large grey box with a big bundle of multicolored wires sticking out of it (Photo 2).

The wires coming out of the power supply have white plastic plugs on the ends of them called molex connectors. There should be several of them connecting to the hadrive, CD drive, floppy dive, motherboard, fan, etc. (Photo 3). You'll want to unplug all of these. Make sure you have them all and that they're pulled free of all thebrackets and cables inside (Photo 4).

Once that's done you'll need to remove the screws that hold the power supply to the case (Photo 5). In some cases the power supply may be rivited to the compter caYou can make short work of the rivets with an electric drill and a metal drill bit.


4/11


After that the power supply should lift right out of the case (Photo 6). For this project you won't need the rest of the computer but keep in mind that it still contains manuseful parts like fans, motors, r ibbon cables, capacitors and resistors just to name a few. Also, the pins on the CPU are made out of gold.

Image Notes1. The power supply is behind this plate.

Image Notes1. Power Supply2. CD drive3. Floppy drive4. Cooling Fan

5. Heatsink and CPU6. Motherboard

Image Notes1. Body of the power supply unit2. Molex connector3. Molex connector


5/11


Step 3:Get Out Your MultimeterEach color of wire coming out of the power supply box supplies a different voltage. Al l wires of the same color supply the same voltage. It's your job to use the multimeto find out what color supplies what voltage. Now I SUPPOSE I COULD tell you the colors and their respective voltages (which I will later) but you should test themanyway just to be safe.

You should start by using your wire cutters to cut all of the wires from the molex connectors. Cut as close to the connector as possible since you may want to have thewires as long as possible(Photo 1). You should also remove the zip ties that are bundling them together. Later, you may want to make your own bundles of each wire

color.

Take one wire of each color and strip a little bit of the insulation from the tip. If you have a terminal strip handy you should connect the wires to that, otherwise try to bethem away from each other so that the tips do not touch each other.

Now let's fire this thing up. You should get the power cord and plug it into the back of the power supply. Plug the other end into a wall outlet. If there's a rocker switch othe back of the power supply flip that to the on position. Next you should take the green wire and touch the bare end off of the metal casing of the power supply. I t shospring to life with the telltale "whirr" of the fan. In order to keep the power supply running while your working you should secure the wire to the case with one of themounting screws (Photo 2). All of the wires are live now so don't let them touch each other! I f they do the power supply will shut off and you'll have to unplug it and pluback in.

Now set your multimeter to DC volts. Keep the black probe touching off the black wire and touch the red probe off of each color of wire. The reading you get from eachcolor is the voltage supplied from that particular color. They should read as follows:

Yellow +12V (Photo 3)Red +5V (Photo 4)Orange +3.3VBlue -12V

White -5V

Your reading may differ a li ttle since the power supply won't put out a stable voltage unless there's a minimum load on it. Since your multimeter isn't enough of a load ymight get slightly different readings.

In addition you'll have these wires:Black - GroundGreen - Power On signalGrey - Power OK SignalPurple - Standby Signal

As you test the wires you should write down the results. You will need them when labeling your posts later. Also, find the decal on the side of the power supply case awrite down the maximum amperage rating of each rail (Photo 5). Try not to exceed these ratings as the power supply will overload and shut off.


6/11



7/11


Step 4:Build an Enclosure...Maybe?While most people seem to add a few binding posts to the case and stuff everything inside I don't recommend it since the wires could interfere with the rotation of the fYou also increase the risk of shorting one of the wires to the case or other components. I think it would be a lot easier to wire everyhting up too, since you can have a more room inside an enclosure.

My enclosure is pretty simple. It's nothing more than five pieces of craft board glued together - all butt joints (Photo 1). My woodworking skills are very limited but I stillfound this to be extremely easy.

The enclosure does not have a back side. Instead, the back of the power supply case makes it up. This allows access to the socket for the power cord and to the masswitch. It also allows the fan to expel exhaust air. Small openings above and below the case allow fresh air to enter the enclosure (Photo 2). The power supply case ishot-glued into the enclosure.

Once side of the case is not glued on. Instead, there are small blocks glued into each corner to keep it place. The side fits snugly into the rest of the enclosure so thatadditional fasteners such as screws or latches are not needed to keep it in place. This allows access to the inside of the enclosure (Photo 3).

Step 5:Making the ConnectionsAll wires of like colors will need to be gathered and connected together. You should remove the zip ties that bundle the wires from each molex connector. Next, cut an

splice all of the wires to the same length and use a ring terminal to hold them together. I bought ring terminals that were rated for wire bigger than the power supply wiThis allows several wires to fit into one connector. It cuts back on materials and time.

Using a ring terminal is easy. Just slip the bare end of the wire into it and use the wire cutters/strippers to crimp the terminal to the wire (Photo 1). Do this for all of thewires except for the grey, purple and green ones. There ary typically a lot of red and black wires coming from the power supply, you'll probably need to use several rinreminals for these (Photo 2).

Now, all of the ring terminals for each color can be slipped over a bolt and put through the front of the enclosure (Photo 3). The ring terminal and he head of the boltshould remain inside while the washer and hex nut are used to secure it from the outside (Photo 4).


8/11


Step 6:Adding the Switch and LED'sIf you don't know how to solder than there are plenty of instructables on it. In any case, you'll need to break out the soldering iron and the solder for this one.

Wiring up the switch is simple enough. Remember that green wire you secured to the case? You just need to interrupt that wire with a toggle switch. Just cut and splicthe green wire somewhere along the middle and solder the two new ends to the terminals of the switch (Photo 1). The switch should be easy enough to mount simply drilling an appropriately sized hole in the enlosure and popping it in (Photo 2 ).

The LED's can get a little t rickier. If you're using a red and a yellow LED then the forward voltages are roughly the same and you can use the same value of resistor foeach. Since the voltages of the grey and purple lines are 5 volts, you'll need two 330 Ohm resistors.

Each LED has a short and a long lead. The short end is the Cathode (-) end and a short piece of wire should be soldered to it. The long end is the Anode (+) and the 3Ohm resistor should be soldered to that. It helps to prepare the LED's in this way before mounting them inside the enclosure. The LED's can easily be mounted in anappropriately sized hole with a drop of crazy glue.

Now all you have to do is solder the purple wire (Standby) to the resistor end of the yellow LED and solder the grey wire (Power OK) to the resistor end of the red LEDNext, the wires coming from the cathode should be connected to the Ground rail (Photo 3).


9/11


Step 7:Finished!And there you have it, a cheap benchtop power supply out of recycled parts. In the near future I will try to start prototyping some elecronic circuits that I will need for amuch bigger project that I have in mind. I believe that this nifty piece of equipment will be invaluable for that process.

As always, I hope you enjoyed reading and hope you found all of the information you need for building your own benchtop power supply. As I said, there are many othinstructables out there on virtually the same thing so you should check them out too.

If you have any questions or comments feel free to leave them in the "comments" section.

Cheers!


10/11


Related Instructables

Recycle an oldpower supplyinto a(nother)fume extractor

by lowercase

A USB PowerControled PlugStrip. With

Isolation.by

toymotorhead

Make a benchpower supplymostly fromrecycled parts

by newtonn2

Guitar TubeAmp FromScratch (Part 1,Transformers)

by asdterror

ATX PowerSupply -->Cheap Bench-Top PowerSupply(Photos)

bymortaldoom780

Convert an ATXPower SupplyInto a RegularDC Power

Supply!by

Sitnalta

Comments

6 comments Add Comment

one_fake_usersays: Dec 11, 2009. 2:36 PM REPA wooden enclosure wouldn't be the best idea with this project I wouldn't think. 1 spark = 1 fire. Get a surge and the caps and resistors go pop, things catcon fire, not a good thing. Like the design though. I think the easiest way of getting a good enclosure would be to gut a second psu and feed the cables fromthe front of the first one into the back of the second one then panel mount everything to the front of the second one. Then bolt the 2 of them together.Minimal construction required.

Hycrosays: Nov 18, 2009. 12:39 PM REPWait...that doesn't look like the computers I had so many of, that looks just like the old PIII 550 I had...it was an awesome little rig, half the parts were missiwhen I got it, and I built it into a pretty reliable computer...

Hycrosays: Nov 18, 2009. 12:11 PM REPI had 10 or more computers just like that one...still got all the mobo's and cases from them...but half the power supplies have burnt out, and a couple didn'thave a power supply when I got them...:P
http://www.instructables.com/id/Another-Benchtop-Power-Supply-from-PC-Power-Supply/?utm_source=pdf&utm_campaign=comments#DISCUSShttp://www.instructables.com/member/Hycro/?utm_source=pdf&utm_campaign=commentshttp://www.instructables.com/member/Hycro/?utm_source=pdf&utm_campaign=commentshttp://www.instructables.com/id/Another-Benchtop-Power-Supply-from-PC-Power-Supply/?utm_source=pdf&utm_campaign=comments#DISCUSShttp://www.instructables.com/member/Hycro/?utm_source=pdf&utm_campaign=commentshttp://www.instructables.com/member/Hycro/?utm_source=pdf&utm_campaign=commentshttp://www.instructables.com/id/Another-Benchtop-Power-Supply-from-PC-Power-Supply/?utm_source=pdf&utm_campaign=comments#DISCUSShttp://www.instructables.com/member/one_fake_user/?utm_source=pdf&utm_campaign=commentshttp://www.instructables.com/member/one_fake_user/?utm_source=pdf&utm_campaign=commentshttp://www.instructables.com/id/Another-Benchtop-Power-Supply-from-PC-Power-Supply/?utm_source=pdf&utm_campaign=comments#commentshttp://www.instructables.com/member/Sitnalta/?utm_source=pdf&utm_campaign=relatedhttp://www.instructables.com/id/Convert-an-ATX-Power-Supply-Into-a-Regular-DC-Powe/?utm_source=pdf&utm_campaign=relatedhttp://www.instructables.com/id/Convert-an-ATX-Power-Supply-Into-a-Regular-DC-Powe/?utm_source=pdf&utm_campaign=relatedhttp://www.instructables.com/id/Convert-an-ATX-Power-Supply-Into-a-Regular-DC-Powe/?utm_source=pdf&utm_campaign=relatedhttp://www.instructables.com/id/Convert-an-ATX-Power-Supply-Into-a-Regular-DC-Powe/?utm_source=pdf&utm_campaign=relatedhttp://www.instructables.com/id/Convert-an-ATX-Power-Supply-Into-a-Regular-DC-Powe/?utm_source=pdf&utm_campaign=relatedhttp://www.instructables.com/id/Convert-an-ATX-Power-Supply-Into-a-Regular-DC-Powe/?utm_source=pdf&utm_campaign=relatedhttp://www.instructables.com/member/mortaldoom780/?utm_source=pdf&utm_campaign=relatedhttp://www.instructables.com/id/ATX-Power-Supply-gt-Cheap-Bench-Top-Power-Supp/?utm_source=pdf&utm_campaign=relatedhttp://www.instructables.com/id/ATX-Power-Supply-gt-Cheap-Bench-Top-Power-Supp/?utm_source=pdf&utm_campaign=relatedhttp://www.instructables.com/id/ATX-Power-Supply-gt-Cheap-Bench-Top-Power-Supp/?utm_source=pdf&utm_campaign=relatedhttp://www.instructables.com/id/ATX-Power-Supply-gt-Cheap-Bench-Top-Power-Supp/?utm_source=pdf&utm_campaign=relatedhttp://www.instructables.com/id/ATX-Power-Supply-gt-Cheap-Bench-Top-Power-Supp/?utm_source=pdf&utm_campaign=relatedhttp://www.instructables.com/id/ATX-Power-Supply-gt-Cheap-Bench-Top-Power-Supp/?utm_source=pdf&utm_campaign=relatedhttp://www.instructables.com/id/ATX-Power-Supply-gt-Cheap-Bench-Top-Power-Supp/?utm_source=pdf&utm_campaign=relatedhttp://www.instructables.com/member/asdterror/?utm_source=pdf&utm_campaign=relatedhttp://www.instructables.com/id/Guitar-Tube-Amp-From-Scratch-Part-1-Transformers/?utm_source=pdf&utm_campaign=relatedhttp://www.instructables.com/id/Guitar-Tube-Amp-From-Scratch-Part-1-Transformers/?utm_source=pdf&utm_campaign=relatedhttp://www.instructables.com/id/Guitar-Tube-Amp-From-Scratch-Part-1-Transformers/?utm_source=pdf&utm_campaign=relatedhttp://www.instructables.com/id/Guitar-Tube-Amp-From-Scratch-Part-1-Transformers/?utm_source=pdf&utm_campaign=relatedhttp://www.instructables.com/id/Guitar-Tube-Amp-From-Scratch-Part-1-Transformers/?utm_source=pdf&utm_campaign=relatedhttp://www.instructables.com/member/newtonn2/?utm_source=pdf&utm_campaign=relatedhttp://www.instructables.com/id/Make-a-bench-power-supply-mostly-from-recycled-par/?utm_source=pdf&utm_campaign=relatedhttp://www.instructables.com/id/Make-a-bench-power-supply-mostly-from-recycled-par/?utm_source=pdf&utm_campaign=relatedhttp://www.instructables.com/id/Make-a-bench-power-supply-mostly-from-recycled-par/?utm_source=pdf&utm_campaign=relatedhttp://www.instructables.com/id/Make-a-bench-power-supply-mostly-from-recycled-par/?utm_source=pdf&utm_campaign=relatedhttp://www.instructables.com/id/Make-a-bench-power-supply-mostly-from-recycled-par/?utm_source=pdf&utm_campaign=relatedhttp://www.instructables.com/member/toymotorhead/?utm_source=pdf&utm_campaign=relatedhttp://www.instructables.com/id/A-USB-Power-Controled-Plug-Strip-With-Isolation/?utm_source=pdf&utm_campaign=relatedhttp://www.instructables.com/id/A-USB-Power-Controled-Plug-Strip-With-Isolation/?utm_source=pdf&utm_campaign=relatedhttp://www.instructables.com/id/A-USB-Power-Controled-Plug-Strip-With-Isolation/?utm_source=pdf&utm_campaign=relatedhttp://www.instructables.com/id/A-USB-Power-Controled-Plug-Strip-With-Isolation/?utm_source=pdf&utm_campaign=relatedhttp://www.instructables.com/id/A-USB-Power-Controled-Plug-Strip-With-Isolation/?utm_source=pdf&utm_campaign=relatedhttp://www.instructables.com/member/lowercase/?utm_source=pdf&utm_campaign=relatedhttp://www.instructables.com/id/Recycle-an-old-power-supply-into-another-fume-ex/?utm_source=pdf&utm_campaign=relatedhttp://www.instructables.com/id/Recycle-an-old-power-supply-into-another-fume-ex/?utm_source=pdf&utm_campaign=relatedhttp://www.instructables.com/id/Recycle-an-old-power-supply-into-another-fume-ex/?utm_source=pdf&utm_campaign=relatedhttp://www.instructables.com/id/Recycle-an-old-power-supply-into-another-fume-ex/?utm_source=pdf&utm_campaign=relatedhttp://www.instructables.com/id/Recycle-an-old-power-supply-into-another-fume-ex/?utm_source=pdf&utm_campaign=related


11/11

http://www instructables com/id/Another Benchtop Power Supply from PC Power Supply/

cpotososays: Oct 30, 2009. 9:08 PM REPOften switching power supplies need to have a load to operate at all. Most AT/ATX benchtop power supply designs I've seen (and I built 2) employ a 5 -10Ohm power resistor between the +5V and GND posts.

LancePenneysays: Oct 31, 2009. 8:56 AM REPYes I have read about the 10 watt resistor used for the minimum load on these power supplies. However I cannot find any at the local electronics storeand I don't want to order one online unless I'm making a big order.For now I'll just use a few lamps or something if I need to draw more power to get it to run stable.

stephenniallsays: Oct 30, 2009. 2:26 PM REPi love the idea of bolts as banana jacks ! I made a Hot foam cutter using 3mm mdf (looks like what your using) and butt joints with hot glue (apart from i cut

out with a laser cutter)
http://www.instructables.com/id/Another-Benchtop-Power-Supply-from-PC-Power-Supply/?utm_source=pdf&utm_campaign=comments#DISCUSShttp://www.instructables.com/member/stephenniall/?utm_source=pdf&utm_campaign=commentshttp://www.instructables.com/member/stephenniall/?utm_source=pdf&utm_campaign=commentshttp://www.instructables.com/id/Another-Benchtop-Power-Supply-from-PC-Power-Supply/?utm_source=pdf&utm_campaign=comments#DISCUSShttp://www.instructables.com/member/LancePenney/?utm_source=pdf&utm_campaign=commentshttp://www.instructables.com/member/LancePenney/?utm_source=pdf&utm_campaign=commentshttp://www.instructables.com/id/Another-Benchtop-Power-Supply-from-PC-Power-Supply/?utm_source=pdf&utm_campaign=comments#DISCUSShttp://www.instructables.com/member/cpotoso/?utm_source=pdf&utm_campaign=commentshttp://www.instructables.com/member/cpotoso/?utm_source=pdf&utm_campaign=comments

Date post:	03-Jun-2018
Category:	Documents
Upload:	helderrui
View:	250 times
Download:	0 times

Another-Benchtop Power Supply From PC Power Supply

Documents