[sdiy] 3140 strobe?

[Pat Kammerer]

Hi All,

I'm working on a build of a zero crossing detector from the op amp cookbook,
which is based on the 3140.  It's weird, but the pulse I get on the output
is barely there, but the there is a pulse on the strobe pin which is strong
enough to drive CMOS.  Does anyone know why this would be?  Do I need to
compensate by putting a cap between pins 1 (null) and 8(strobe), or do I
need to tie pin 8(strobe) to the negative rail?  Any help would be
appreciated.  I've built a few circuits with this chip, and never have I run
across one that acts weird like this.

Thanks to everyone,
Pat