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3 wire fan

trulytest

Sep 5, 2012
10
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Sep 5, 2012
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Hi, I have a 3 wire fan (red, black and white). When I connect it to the 12 Volts and 60mA (without 3rd yellow wire) it is spinning, but not as fast as normal 2 wire fan. I tried to make 5V from 12V using 100 Ohm resistor (hope I calculated it right) and connect it to the yellow one, but it didn't work at all. Anyone know how to control it?
 

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CocaCola

Apr 7, 2012
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Hi, I have a 3 wire fan (red, black and white). When I connect it to the 12 Volts and 60mA (without 3rd yellow wire) it is spinning, but not as fast as normal 2 wire fan.

Have you considered it's not designed to spin as fast aka it's a different RPM fan?

I tried to make 5V from 12V using 100 Ohm resistor (hope I calculated it right)
I doubt it... A better choice would have been a voltage divider... BUT, THIS THIS ISN'T RELEVANT HERE AS THAT ISN'T WHAT YOU DO!

The 'yellow' wire on these fans is an OUTPUT aka a tachometer, not an input!

Anyone know how to control it?
The proper way is to use PWM on the red and black wires and monitor the fans speed via the yellow tachometer wire...

Short of that you simply hook up the black and red wire to the proper voltage and sufficient current power supply...
 

trulytest

Sep 5, 2012
10
Joined
Sep 5, 2012
Messages
10
Uhh, I didn't know the yellow one is actually used as a tachometer, srry :D But thanks for information.

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