For the 24 VAC there are screw terminals close by, and that's the=20
majority of the items. For the 120 and 240, that's a good idea. refresh=20
my memory. There was an article several years ago, but I kept the issues=20
of was it Circuit Cellar or Nuts & Volts. Will have to go back to that=20
and refresh the mind. :)
On 9/16/13 5:25 PM, Mark Hanchey wrote:
> On 9/16/2013 8:33 AM, Carl Denk wrote:
>> I have a home project coming down the road mainly HVAC stuff of digital
>> inputs to a PIC probably a 18F??. THe inputs would be only to sense
>> on/off. The voltages would be 24 VAC, 120 VAC, and 240 VAC. I'm thinking
>> through an Opto isolator with a resistor and capacitor on the AC side.
>>
> I always think non contact whenever working with sensing AC. Have you
> thought about using a circuit like those in the non contact voltage
> detector pens ? You would only have to place the coil near the HVAC wire
> that becomes live when powered.
>
> The circuits are as simple a couple transistors and would be very safe
> since you don't have to alter the HVAC at all.
> Mark
>

--=20
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