Re: Easy, Inexpensive Cooling Fan, Excelway Case

Gary Anderson
 

Hi Arv,
Thanks for reporting back the results of your experiment.  I am thinking that you are going after a 'simple' solution where the fan doesn't run continuously.  For micro-controller control, I would switch the fan's ground (low side) with a logic level N-FET. Then I got to thinking that instead of using a controller, that one could use a simple RC circuit to control the turn-off delay.   I would think that during a CW transmit, that the fan should remain On, and not switch On/Off with every dit and dah.  Below is the idea for review/vetting/ or seeding another solution.  This should also be a much softer shutoff.  Little r added for discussion point of a softer start if it helps with noise.  (Of course r could be 0.)

Regards,
Gary
 

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