Simple pwm discreet

767

11:54:59

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. 

published 10 years ago

hurz

10 years ago

Bookmarked ;-)

barron

10 years ago

Wow how simple is that !!! Ingenious a difference amp and power control. Nice one. Also book marked

barron

10 years ago

Also like that idea of using mains frequency as oscillator for the triangle wave.

acidman

10 years ago

Nice ! You clearly have good grasp of how things work as a simple search on here reveals a Host of pwm designs but none are even close to the simplicity and function of this. Really well done. Also bookmarked ************

acidman

10 years ago

Why not publish the how you used and converted the mains frequency to that triangle ramp control signal we might find that interesting.

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