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Simple Project Help Please! Answered

Heres the deal: I have a set of old computer speakers and a pair of computer case fans that just happen to fit inside the speaker housings. What I want to do is utilize the existing power cable (input: 120V 60Hz 25W, output: 15V DC 800mA) to power the fans. The fans are both labeled "12V DC 0.2A" and I really just want to know: A) will running the fans at 15V damage them, and B) is there anyway I could control the fan speed?

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panic (author)2007-03-30

my point: A) 15V will NOT damage a 12V fan.But it is recommended use some device to fit the voltage.You can just put 3 diodes in series to reduce the voltage. B) Some kind of fans has a control-pin to adjust the speed.I think change the supply voltage will DO change the speed.

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LasVegas (author)panic2007-03-30

Just put a potentiometer in series with the fans (in parallel) to adjust the speed. One end to the power, the other end and the center to the fans.

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britishgecko31 (author)panic2007-03-30

Thanks, but just out of curiosity, why diodes (and why 3)? I thought those just limited the direction of the current? Why not a resistor(s)? And these fans are really old--functional, but old--no speed control pin. What kind of switch would I need to control the voltage?

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5Volt (author)2007-03-30

Recycling computer speakers and fans into an operator cooler? Cool ! Pun intended. Make sure to take pictures and post the instructable. I'll like it. Oh, the diodes are good. Ciao

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trebuchet03 (author)2007-03-30

A) Probably will shorten their service life B) Sure - control the voltage :)

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