I've got a 3V DC toy motor that I'd like to convert to variable speed using a PWM circuit. I found an $5 PWM controller that would work. This expects a 100 K\$\Omega\$ potentiometer as its speed input.
I want to set the speed using a mechanical trigger (like on a variable-speed drill), but that means I have an input that travels only 5-10 mm. The potentiometers I've found are rotary (270° travel) or linear/slider (20 mm travel). If I were to use these, I'd only be able to use part of the 0-100 k\$\Omega\$ range.
How should I approach this?
- create a mechanical system to convert the trigger travel into the full range of the pot,
- is there a way to get the full rpm range out of the PWM circuit using only part of the potmeter range?
- or should I build a custom PWM circuit instead?