Here the situation. I have 2 fans controlled by 1 PWM signal. Works perfectly like that.
Now, I want to trick one to be always 40% ahead of the other (and mechanically, have a minimum speed of 40%).
so for instance :
- PWM signal is 20% : Fan 1 goes at 20% of the speed, Fan 2 goes at 60% of the speed
- PWM signal is 40% : Fan 1 goes at 40% of the speed, Fan 2 goes at 80% of the speed
- PWM signal is 60% : Fan 1 goes at 60% of the speed, Fan 2 goes at full speed
- PWM signal is 80% : Fan 1 goes at 80% of the speed, Fan 2 goes at full speed
Any idea of a circuitry that could modify the PWM signal for my fan 2?
I do not need it to be perfectly accurate on the percentage,even if the added value fluctuates between beginning of the scale and end of the scale, that would be OK.