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[DPRG] Board indication of 120VAC

Subject: [DPRG] Board indication of 120VAC
From: Bill Boyer daweasel at swbell.net
Date: Wed Jun 1 14:10:26 CDT 2005

Also a poorman's ring indicator for phone work. Early schematics for making 
a lamp flash when the phone rang used this circuit to drive a triac.

We actually had a product which used some manufactured sensors with a 
similar design. Unfortunately they were the part most likely to fail and 
were discontinued about 10 years ago.

----- Original Message ----- 

> In the old days, the NE2 was taped to a photosensor. These were
> the beginnings of opto couplers we have today in solid state
> form. The same can still be done today, you know, to have
> isolation from the 120VAC side to the micro side.

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