A very simple pwm consisting a ramped signal a 5v reference and a power switch and of course a pot for the adjustment. The pnp bjt wasn't needed for me but included it here. I needed to control the brightness of 2×20w halogen bulbs in series while maintaining a good colour temperature over a reasonable range. For the signal ramp i picked up the mains frequency for me 50hz and massaged it a bit. but for clarity I just used the built in source here. And I've exaggerated the range of adjustment beyond my needs for versatility.
