Intro: Computer Power Supply - Quick Hack
There are many examples of modifying the standard CPU power supply on this site but if, like me, you just want a fistful of power and want it NOW then the power supply is not the project!
Even a hack has to be servicable and safe so this note describes a quick modification.
A front panel is fitted to hold the power switch, indicator light and terminals;
with the panel space now available then other components like a variable output can be added if desired.
Step 1: How to Fit a Panel
I vaguely remembered that the mounting screw size was metric M3 which did not make sense as the original fittings are self-tapping screws but a quick test showed that they took a loose fit - strange!?
Using oversize nuts as spacers allowed the M3 screw to be tightened properly :)
You now have four mounting points for a panel or other casework.
By fitting M3 threaded spacers allows a false front panel to be mounted giving plenty of scope for fixing the necessary items
Step 2: What I Actually Did...
I decided to go quick-and-dirty in my impatience so I used only the minimum of brackets.
Oops! I mounted the switch up-side down!
I did not have enough terminals for all outputs at this time but two was enough for the LED strip lighting that I wanted to power.
I will fit extra terminals in due course especialy as the +12 & -12v is useful for Op-Amp. projects.
Do not underestimate the usefulness of the negative 5 and 12 volts as bias voltages particularly for adding a variable output.
I note that others have gone to the trouble of adding a variable voltage regulator to make the unit more versatile though I would point out that as these power supplies give fixed voltages and are current limited then only a power transistor (e.g TIP 121), a base resistor and a potentiometer is needed.