Question about delay timer with LM339 comparator?

Thread Starter

samy555

Joined May 24, 2010
116
Hi

Is it C4, C5 or both which control the time delay to ON the transistor?

Why R4 (3.9M)?
thank you very much
 

wayneh

Joined Sep 9, 2010
16,384
C5 controls the turn-on delay once the comparator switches to high. R4 is for a small amount if hysteresis to reduce of chatter in switching the comparator.
 

MikeML

Joined Oct 2, 2009
5,444
What a horribly complicated circuit.

You just want to light a LED x seconds after V2 is switched on?

Or y seconds after V1 is switched on?

Oh, and this is a death trap. Note that it is referenced to AC line ground, and it doesn't meet the terms of service here...
 
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