optoisolators

[Foaad]

hi, im going to be using the sharp PC814X for zero crossing detection
(dimmer circuity), im just wondering what should i expect at the
output? a square wave everytime it crosses the zero?

 

[CBarn24050]

Subject: optoisolators
From: foaadnami@gmail.com (Foaad)
Date: 12/01/2005 05:12 GMT Standard Time
Message-id: <ce15315b.0501112112.76981553@posting.google.com

hi, im going to be using the sharp PC814X for zero crossing detection
(dimmer circuity), im just wondering what should i expect at the
output? a square wave everytime it crosses the zero?

Hi, I use these all the time for this application. The output waveform depends
on your resistor choices. For a 415V supply, 15K series resistor, 1K across the
diode and a 10K pull up on the output side gives a 1.5mS posative pulse at each
crossing pulse.