DC lamp dimmer

Thread Starter


Joined Sep 27, 2005
I want to build a dimmer for a DC lamp, using a potentiometer as a voltage divider. The lamp is 6V 30W. The power supply I am using is 5VDC, 6 Amp switchmode.

My question is what should be the resistance of the pot? Am I correct in thinking it should be close to that of the bulb (i.e. approx 5/6 ohms)? I want to be able to dim the lamp by up to 50%.


Joined Sep 24, 2005
The serial potmeter not a good idea: need a really big one. If the PSU adjusting no possible use a small PWM regulator.