I've found a few threads but nothing with exactly looking for what I'm looking for.
I need to switch 24VAC (HVAC control) and 120VAC (2A and 10A) with a PIC. What is the best way to do this? Opto-Isolated TRIAC, SSR?
Your suggestions on your favorite parts for the job would be greatly appreciated.
Thanks,
John
just drive a low voltage coil relay via a NPN transistor in open collector state through the coil. Emitter to common and base to an output via a resistor to force the tranny into saturation. P.S. put a FlyBack diode on the coil other wise, you'll take out your tranny and maybe the pic in a short time. also., make sure you mount the relays away from the pic. We had cases where the EMF of the coil actually caused problems with the program in the PIC which forced a reload of the code.
I like opto isolated solid state relays for my home projects, for their ruggedness and simplicity of a direct logic drive. But for production designs, they are high cost.
I agree. When your are coming to do your own circuit, then you cannot beat an isolating transformer and a SCR/Triac for cost saving. You would have to cide into your pic to drive them with a few kilhertz square wave though.
Rob.
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