Dan Spiegelberg
New Member
I would like some help on a circuit I came across on the
internet. I am trying to generate PWM by going thru a
comparator. +input is fed 0 - 10vdc and -input gets fed
a ramp which is in sync. w/ the ac line freq. The lights
dim up and down OK, however I notice jitter on the ramp when
the 0 - 10vdc signal is changed. This is a problem because
I would like to feed this ramp signal to more than one light
channel. I tried an op amp(LM324) wired as a comparator
and a comparator(LM339).
Both give about the same results. Any ideas as to how to get
rid of this jitter?
Thanks.
I tried a buffer as someone suggested, but that didnt help. I used a lm324 as
a unity gain amp between the ramp circuit and the comparator.
internet. I am trying to generate PWM by going thru a
comparator. +input is fed 0 - 10vdc and -input gets fed
a ramp which is in sync. w/ the ac line freq. The lights
dim up and down OK, however I notice jitter on the ramp when
the 0 - 10vdc signal is changed. This is a problem because
I would like to feed this ramp signal to more than one light
channel. I tried an op amp(LM324) wired as a comparator
and a comparator(LM339).
Both give about the same results. Any ideas as to how to get
rid of this jitter?
Thanks.
I tried a buffer as someone suggested, but that didnt help. I used a lm324 as
a unity gain amp between the ramp circuit and the comparator.
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