Light switch sensing

[mister_e]

Sometime current transformer are great, sometime, when misplaced and/or not properly insulated they can ruine your life and reading... just think what happen if they're located to close of a transformer, or close to a switching power supply, or, or, or.

EDIT: Did you place any kind of load at the output of your current transformer before sending it to your op-amp???

[Luciano]

Hi,

See picture below.

Best regards,

Luciano

[George]

Thanks Luciano,

I had thought of that initially, but disregarded it as the TRIAC would have to be off at the same time as the light bulb is on. But seeing your picture made me think about it, and I figured that I can just measure the voltage there just after zero crossing and before I trigger the triac - either that or charge a little cap through a diode and read the cap anytime. Makes it a really simple circuit too!! Will try it as soon as I get back from holiday - am off to Fiji for a week, BULA!!!

[Luciano]

... or charge a little cap through a diode and read the cap anytime.

Yes, this was the idea.

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AN521 Interfacing to AC Power Lines
http://ww1.microchip.com/downloads/e...tes/00521c.pdf

AVR182: Zero Cross Detector
http://www.atmel.com/dyn/resources/p...ts/doc2508.pdf

* * *

Enjoy your holiday!

Luciano