I have a 12V, 5m long LED strip and an adapter (12V 1A). I want to control the brightness of the LED strip with a potentiometer, I found a simple circuit that involves only a pot and IRFZ44N transistor.( datasheet here ) It was working great, but it wasn't very bright.
When i connected the LED strip only to the adapter it was very bright but as I soldered the circuit it wasn't very bright. Also I measured that the output voltage dropped from 12V to about 9.6V.