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Training the hand and mind since 1982.

Tuesday, December 1, 2015

Camper fan speed control

During our last camping trip we really need to control the exhaust fan over the stove,  it was really cold out and the fan was a bit to strong. So I came up with a couple ideas:

1. Use a resistors to drop the speed. The problem with this is the power loss. Don't forget were on batteries and do no wish to dump energy as heat.

2. PWM - this would be the most efficient use of power and would not required expensive components.

Here is the schematic:





Used vero-board for this project since it was so small





Frequency of PWM is out of the range of hearing so it's quiet, I originally tried 1khz PWM frequency on the breadboard but it made the motor sound like a screeching cat. So I made C1 smaller until i could no hear the PWM.