A zero crossing detector is a device that detects when an AC waveform switches polarity (crosses zero volts from positive to negative or negative to positive).
Anything that's opto-isolated has the input circuitry and output circuitry electrically isolated and usually insulated for a couple of thousand volts. This is done by optically coupling the input and output, usually using an LED and photodetector separated by a transparent insulator.
Fairchild Semiconductor makes lots of them that have triac outputs designed for triggering a power triac for light dimmer applications. There are some on the market with logic outputs for use with a microprocessor, but I don't have a link to one. Any of the electronics parts distributors that sell to hobbyists like DigiKey, Mouser, Jameco, and others would carry them.
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Post Edited (Mike Green) : 3/7/2009 6:46:51 PM GMT
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Dave
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Dave Andreae
Parallax Tech Support·
Anything that's opto-isolated has the input circuitry and output circuitry electrically isolated and usually insulated for a couple of thousand volts. This is done by optically coupling the input and output, usually using an LED and photodetector separated by a transparent insulator.
Fairchild Semiconductor makes lots of them that have triac outputs designed for triggering a power triac for light dimmer applications. There are some on the market with logic outputs for use with a microprocessor, but I don't have a link to one. Any of the electronics parts distributors that sell to hobbyists like DigiKey, Mouser, Jameco, and others would carry them.
Please do not post duplicate messages. It's against forum rules. You should delete one of your messages using the X in the right upper corner of the message box.
Post Edited (Mike Green) : 3/7/2009 6:46:51 PM GMT