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Yellowsnow17
20th October 2004, 06:08
Hey All,

This is a project log to track my progress in building a mini power supply for my desk. I like to fiddle with electronics as a hobby, and I've always wanted a variable DC power supply so I can stop using old computer PSU's to test my circuits. It sucked every time I wanted to test a circuit or LED or whatever I had on my desk, I always had to crimp a molex on it and plug it into a computer power supply. But no more!

Mnpctech has graciously sent me a sample project box (thanks a lot! :)) to put my mini DC power supply in. For more information, see this thread:
http://www.wizdforums.co.uk/showthread.php?t=625

Ok, the goal is to design a variable power supply and fit it in the box. I want it to be able to achieve approximately 0-18 volts and deliver 1.5 amps of current. I haven't drawn up the box in CAD yet, but will do that very shortly. Also, I have an electrical schematic drawn up which I will either scan or do something else with to show here as well. This is only the second project log I've attempted to write so bear with me. Detail CAD and electrical drawings will be up soon, but for now a couple teaser pics:

http://img.photobucket.com/albums/v158/DENorth17/PS1.jpg
The project box from mnpctech and the first piece of hardware that was received: The world's smallest* LED voltmeter.

*not a guarantee...

http://img.photobucket.com/albums/v158/DENorth17/PS2.jpg
The voltmeter hooked up to my breadboard to see if it works. It's displaying erroneous information because it's not hooked up to anything, just being powered. This little voltmeter will go on the front of the box and display what the current output voltage is.

Pics up soon of the overall schematic so you can see what's going on...

mnpctech
20th October 2004, 13:47
<-- Grabs Beers.

This ought be sweet.

fillip
20th October 2004, 13:50
How much was and where did you buy that nifty little voltmeter?


loving the look of this one already ^_^

toby
20th October 2004, 14:23
looks interesting and very handy!

Yellowsnow17
20th October 2004, 17:19
<-- Grabs Beers.

This ought be sweet.Wow, thanks for the compliment. And again, thanks for the project box!
How much was and where did you buy that nifty little voltmeter?I bought it from Allied Electronics which is a distributor here in the US. The voltmeter comes from a company called Lascar, which I found out yesterday is located in the UK. You can buy direct from them on their website: www.lascarelectronics.com (http://www.lascarelectronics.com/) P/N OEM 1B-LED. I paid about $23 USD for it...

EDIT: Since I'm such a nice guy, here's your direct link fillip:
http://www.lascarelectronics.com/products.cfm?STOCKNO=OEM%201B%2DLED&CFID=2152730&CFTOKEN=83046012

Knipex
20th October 2004, 20:01
Brings the chips to go with the beer..... ^_^ (and some steaks:D )

Yellowsnow17
20th October 2004, 20:06
Brings the chips to go with the beer..... ^_^ (and some steaks:D )
ahh, now where is my guinness avatar from bit-tech... :D

fillip
20th October 2004, 22:33
EDIT: Since I'm such a nice guy, here's your direct link fillip:
http://www.lascarelectronics.com/products.cfm?STOCKNO=OEM%201B%2DLED&CFID=2152730&CFTOKEN=83046012
Awwww :wub:

mnpctech
20th October 2004, 23:29
I just spent 20 mins sniffin around Lascar's site. Nice call!

Yellowsnow17
25th October 2004, 00:09
Hey guys!

Ok, I know I said I would post an electrical schematic and a CAD drawing of the final product, but when I sat down yesterday to work on this project, I decided that my time would be best spent actually WORKING on the project instead of doing "paperwork" so I dont have those details yet. what I DO have is a working power supply for you...:D

This is the complete parts list as it was on saturday morning:
http://img.photobucket.com/albums/v158/DENorth17/PS3.jpg

After many hours of soldering:
http://img.photobucket.com/albums/v158/DENorth17/PS4.jpg

And after a few more hours of work we have all the components together and plugged into the wall. Power comes into the wall and goes through the transformer, which turns 110 AC down to 18 AC. Then it goes through a rectifier which turns that AC into DC voltage. Then that dc voltage goes into my regulator where I can then vary it from 1.5-16v DC by simply turning the knob on that blue potentiometer in the first pic. You can see(maybe) the voltmeter is on and reading zero. A good start!
http://img.photobucket.com/albums/v158/DENorth17/PS5.jpg

Finally, here is my homebrewed power supply powering a green LED off of my breadboard. OMFG it works!?!?
http://img.photobucket.com/albums/v158/DENorth17/PS6.jpg
If you have a sharp eye, you can see in that last pic that the decimal point on the voltmeter is off by one place.(I'm putting 3.78 volts across the led, not 37.8! :eek: ) That means I soldered a wire in the wrong spot on the voltmeter. Meh, should be easy to fix...

That LED test was done about five minutes ago and was the first successful test of my power supply. I'm absolutely thrilled and surprised that it worked on the first try! Next update: Stuffing all of this inside the project box and more testing.

fivecheebs
25th October 2004, 01:08
nice one snowey :)

Good luck with the "stuffing" :)