In article ,
D Yuniskis wrote:
I've got a (Vellerman) PWM device which is DC controlled. I'd like to
use it such that it fades up to max when a simple DC switch is made,
then fades out when it is broken. I can get it to do this using a
simple RC circuit - but the 'law' of the fades isn't as linear as I'd
like. Any clever way of doing it?

Constant current source into a cap.

The constant current source into the cap is easy enough - but the constant
current load?

--
*I used to have an open mind but my brains kept falling out *

Dave Plowman London SW
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