Sunday, 12 August 2007

Making a lab-type power supply from a PC power supply

Hey folks, welcome to another installment of staying indoors! Apparently a storm was coming this weekend so the tramping I had been planing on was off the table. So yesterday I obtained an old PC power supply (for free from uni) and converted it into a DC power supply for my electronics projects. Didn't take to long and I took a few photos along the way to document it.

The Donor power supply with cables coming out the back.

Removed the cover (ignore the blatant Do not remove Dangerous Voltages sign)

blow out all the dust and crap
And take a look inside

Snipped off all the wires (too close really) about 2 seconds afterwards realised that a bit longer wires would have halved my soldering!
Then i soldered all the sensor cables to there appropriate cables, put a load resistor across the +5 to grnd rail and put a LED in series with a current limiting resistor on the power ok channel. Shorted the power on channel (that usually comes from PC to tell the PSU to turn on) And mounted the red and black terminals you can see here: (Those terminals are expen$ive by the way, this project was supposed to be almost free but I spent $20 on the set of them!)

Detail of the two +5 volt wires soldered to the inside of the terminal:

Testing time! Got the volt meter out, crossed my fingers, stood back a we way nervously and flicked the switch on the mains.

It did work even tho the photo says 0.0V I just turned the power back off before taking the photo!
Then I added the rest of the terminals, made Red + 5V, Black -5V, Green Ground, Yellow and Blue +/- 12 V respectively.

Bit of vivid to remind myself of that arangment and I was done!
And another saturday gone! Course work blissfully forgotten! And one last picture showing the power supplying wonderfull electricity to my microcontroller board from the last post.

Wednesday, 1 August 2007


Hey ya folks - thought since I'm not getting out and about in the natural world much now that its getting colder and my workload is getting bigger and bigger I would share my current electrical project. I'm slowly collecting tools and my desk is getting further and further towards a workbench!

This here is a microcontroller connected to 35 LED's, 2 buttons and a variable dial. Pretty much is a very basic computer! It displays characters on the screen and scrolls through a message.
Of coarse I wasn't satisfied with just that so my lab partner and I having finished the text program (yes we had to program it all as well as build it).
We ended up making a snake game for it. Buttons simply changing direction. it still needs a little work which is annoying since the assignment is due in 2 days...
Anyhow the report is worth 70% of the marks so I should really really start that now instead of posting here!