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03/24/2006: "Part 3: Power it up, light it up!"
Ok we are almost done...I wanted to give my supply a little pizzazz so splurged and spent $2.00 for a lighted fan guard and mounted it to the top of the unit. The original guard was your standard concentric circles. 
Of course those had to go… 
And here it is all together. 
Now we will route the fan and light wires through one of the fan mounting holes and secure them with epoxy. 
After making the splice I shrunk wrapped each and then one more piece to hold it all together.
 |  |
Next step is to solder in the resistor. Also notice the red arrow in the pic. The mounting ear of the fan had to be cut off to keep it from hitting the switch.
Since this is a heat producer it needs to have some sort of heat sink to keep it from burning up. There was not room to wire it to the back so I came up with what I think is a better way. Thermal epoxy.
This is a two part epoxy with thermal properties. They carry two types, Artic Silver or Artic Alumina. The difference being of course a silver or aluminum base. I found this at my local “Computer Deli” but you can also order it online at ArticSilver.com
Here is a quote from their web site:
Characteristics:
Arctic Alumina Adhesive uses a layered
composite of aluminum oxide and boron nitride.
Arctic Alumina Adhesive is a pure electrical
insulator, neither electrically conductive nor capacitive.
A set of Arctic Alumina Thermal Adhesive
consists of two tubes containing a total of
5 grams of adhesive (2.5 grams each of parts
A and B) and a plastic reusable mixing wand. (Approximately 3cc total adhesive.)
Although lighter per set than Arctic Silver
Adhesive due to its use of ceramics rather than silver,
each set of Arctic Alumina Adhesive
contains the same amount of adhesive by
volume as a set of Arctic Silver adhesive
and will cover the same area.
CAUTION!
Arctic Alumina Thermal Adhesive is a permanent adhesive.
Any components you attach together with Arctic Alumina Thermal Adhesive will stay attached forever.
Here it is all glued up and ready to close the cover.
For the last step I added some old case feet I had laying around.
Here it is, the finished bench unit!
Here it is turned on.
Even looks good from the back!
Here are voltages I recorded
 |  |  |
| 3 volts | 5 volts | 7 volts |
 |  |  |
| 12 volts | 17 volts | 24 volts |
Well that's it! I hope you have as much fun building your own bench unit as I did.
Replies: 3 Comments
Hello! This is Matthew Beckler (mat_the_w on most websites), checking out your conversion. I really like how your power supply ended up, you really put a lot of quality work into your supply. I really like the heat-shrink tubing, I wish I had some for my project. Once, I (accidentally) left my power supply on overnight, and the resistor didn't really get very warm, so the quality heatsink compound might be overkill, but better safe than sorry, eh? Great project, and good luck with the next one!
Awesome Project! said @ 03/27/2006 11:22 PM CST
Hi Matt! Thanks for the praise (kicks toe in dirt)! Shrink wrap rules! Can make even a bad job look good! I wouldn’t do anything with out it. As far as the resistor goes I tend to go with the better safe than sorry theory. I left my psu on for several hours myself and like you have not noticed any significant amount of heat. I mainly needed a way to mount the resistor and had heard the guys at the computer store talking about this stuff so I thought I would try it. For me it worked great. Well thanks again for all the words of encouragement, but remember it was your original post that inspired me to do this, so let me say Thank You!
Thanks Matt said @ 03/29/2006 05:12 PM CST
Here's a cool trick, but be carefull. As you might know, the +5 is the regulated voltage. The rest are just "along for the ride". To get a 12v regulated supply, locate the trace from the +5 output that feeds back into the regulation cct. It will be a small trace sometimes leading to a chip. Cut it, then hook up a trimpot from 12v to ground, and wire the wiper to the +5v feedback cct. You will have to play a bit with the value of the pot, so you get enough current in the feedback, but dont over heat the pot. Set the wiper about half way. Turn on the supply and monitor the +12. With the feedback pot half way (approx 6v), the cct will be shutting down, trying to lower the voltage. At some point it stabilizes, and you can dial in your desired voltage near 12v. This is now regulated. stability is a bit of an issue, but I have had luck with a few of these supplies used for RC car chargers. Rob
Rob Lion said @ 04/12/2006 03:42 PM CST
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