Tuesday, August 14, 2012

DIY: Power Supply

I modified the following Power Supply Unit (PSU) to use with a 12vdc RC Battery Charger. If you have an old computer (PC) PSU collecting dust or your thinking of tossing one into the trash then consider this alternative. Rather than spending an arm and a leg for what they want for those specifically made for the 12vdc RC Battery Chargers this modification might be the sweet deal your looking for, it certainly was for myself.

A modified PSU as such would also make a pretty good Electronics Lab or Bench Power Supply. To illustrate, I also use the +5vdc output to power my RC Helicopters RX, Servos and GYRO to effectively bypass powering the motor during it's mechanical setup. This eliminates the risk of the heli accidentally powering up the motor during the setup procedure. Normally we would mechanically or electrically disengage the motor or use a separate battery pack to bypass the ESC when setting up our helicopters. And occasionally I have used this PSU to power many of my smaller electronic projects but these are only a few examples as to possible uses. Not to be condescending but the only limit would be our imagination.

Gotcha: The best PSU for this type of modification would be a high AMP or highest AMP PC power supply we can find. This is because some of the really old ones just don't have enough juice or amperage to power more than one charger if any. Alternately if we don't have a suitable PSU kicking around you might canvas family or friends to see if they have anything worth using. However for reasonable prices a good if not the best source of used equipment therefor high amperage power supplies would be from sites such as eBay or Craigslist. 

WARNING: I was working on a device with the potential to KILL! 
I can't be any more serious as a typical PC Power Supply uses 120vac or 240vac for power input. Please, this article shouldn't be considered complete instructions on how to build or modify a PSU therefor I have been deliberately vague with it's content. Do your homework, research carefully and use your own best judgement before tackling a job of this nature. A little common sense can go along way, first and foremost be sure of your abilities then be sure of your wiring (double, triple check) and don't touch anything you shouldn't while the power is on!
Recycle, Reduce and Reuse
My modified PSU supports 35 AMP per rail w/ connections for +12v (Yellow) +5v (Red) and Ground (Black). Available for my use are three separate +12vdc power rails however as shown in the images I'm only using one +12vdc output along with one +5vdc output. The red LED indicates 'Power-on' with the blue LED to indicate 'Stand-by' power and the Toggle Switch powers the unit on/off.

Built using the following diagram

I didn't add the three fuses shown in the diagram because this PSU is protected with it's own set of fuses from the manufacture. But I would recommend you consider adding the fuses regardless as it's probably good engineering. Put simply the additional fuses adds another level of security and piece of mind

Note: Within the image notice the colours of the wire connections correspond to the colours of the pinouts. Also the 10Ώ 10w Resistor as shown is very important because PC Power Supplies generally don't like operating without a constant load to stabilize their voltage output.
Click image to zoom in

Build one for yourself?

Rather than rewrite the book I would suggest looking to Google (see links) as I did for information and inspiration. Found with a simple search would be enough information along with a number of well written (and not so many) tutorials on how to build your own Bench Power Supply. The only real difficulty is finding a suitable high amperage PC Power Supply for your project. 

In closing if anyone decides to take on a project like the one outlined within this article be sure to come back and share your creation ...

No comments:

Post a Comment