Resistance of a pot 1

[insideman]

Iwant to use a pot to "tickle" a Darlington in order to control power to a small (15 watt) motor. Does it matter if the pot is 5 K or 500 K?

 

[itsmoked]

1) A darlington is voltage controlled and has insane gain.

2) A pot is generally lousy as they will eventually get intermittent causing all sorts of strange happenings.

3) Your darlington will be running in the linear region if you do this. This means it's going to have many watts spewing from it! It will need very serious heat sinking.

4) The proper way to do this is by PWMing the motor. Turning the transistor either fully ON or fully OFF with a pulse train. The more it's on the more the motor sees.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com