Greetings. I'm starting up a small computer repair shop and I noticed that my inventory has a ton of old fans. I'm looking to make a device that I can plug computer fans into to test them. Yes, I know I can use a 9-volt and a couple wires, but it's been years since I actually made something and would like to refresh the data instilled in me by my father before he died. I'd like the box to be able do this:
1) Either plug directly into the wall or use an AC power adapter (most likely wall).
2) Have connectors to plug in various fan types (3-pin bearing in mind that some 3-pins have wires in different spots, 2-pin, etc.)
3a) Have a selector switch for voltages from 5v-12v or any other voltages I'd need.
3b) Variable potentiometer with meter (analog or digital (which would be cool)) to display output voltage (speed control).
4) In-line fuse for safety.
5) On/Off switch.

If someone would be willing to draw up a schematic for this, I'd appreciate it. I'm not too good at drawing them, but I can understand them pretty well (I can tell the difference between a resistor symbol and a capacitor symbol) and am fairly good at assembly. Thank you in advance.

Drew Vedbraaten
First Aid Computing
"We breathe new life into old computers!"

 

you can use LM317 to vary your output voltage. check the datasheet and you will find your circuit.

http://www.national.com/JS/searchDocument.do?textfield=LM317

moz

 

Thanks, Moz, for the link. I'm going to assume that the lead going off on the bottom right is also a voltage out. It does worry me a little to see annotaion symbols present without the descriptors. I will attempt this as soon as I am able to get the cash for parts.

Again, thanks. If there are any other ideas out there, please feel free to chime in with them.

Drew Vedbraaten
First Aid Computing
"We breathe new life into old computers!"