Electronics > Projects, Designs, and Technical Stuff
Fan PWM control using a signal generator.
drummerdimitri:
I would like to control the speed of a fan by supplying it with 12V DC and using a PWM signal from my function generator to control its speed.
I have tried using a 25 KHz switching frequency and started at 30% duty cycle with 1V RMS but was not able to control the speed.
Should I connect my generator's ground to the black lead on the fan and the positive side to the blue cable?
Also, is it ok to leave the yellow (tach) cable unused?
ogden:
You can't put 1V RMS AC sine into 12V DC fan and expect it to rotate. Voltage is insufficient and fan will not like reverse voltage as well. Your signal generator shall supply 12V DC pulses.
drummerdimitri:
--- Quote from: ogden on May 14, 2019, 10:10:17 am ---You can't put 1V RMS AC sine into 12V DC fan and expect it to rotate. Voltage is insufficient and fan will not like reverse voltage as well. Your signal generator shall supply 12V DC pulses.
--- End quote ---
What is the purpose of the Blue PWM cable in that case if I only need the red and black ones for PWM?
ogden:
--- Quote from: drummerdimitri on May 14, 2019, 10:19:49 am ---
--- Quote from: ogden on May 14, 2019, 10:10:17 am ---You can't put 1V RMS AC sine into 12V DC fan and expect it to rotate. Voltage is insufficient and fan will not like reverse voltage as well. Your signal generator shall supply 12V DC pulses.
--- End quote ---
What is the purpose of the Blue PWM cable in that case if I only need the red and black ones for PWM?
--- End quote ---
Third wire (in your case blue) is output signal from FAN - to measure fan speed (RPM). You shall PWM-modulate supply voltage of the fan, 12V (red wire).
[edit] As corrected later - you have 4-wire fan which means that blue wire is fan PWM control (logic) signal indeed.
OM222O:
connect the output of the function generator to a BJT or a FET, which then drives the motor from a 12V supply. you're feeding it very little voltage at it's output!
Navigation
[0] Message Index
[#] Next page
Go to full version