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wireless motion sensor and form C relay

Posted by hacksaw (My Page) on
Wed, Mar 23, 11 at 13:50

I'm seeking to connect a wireless motion sensor to my hard wired door bell chime. I see that many of the wireless motion sensor receivers have a form C dry contact relay with optional NO/NC positions. Being an "old timer" I'm only familiar with electromagnetic relays, can the door bell wire connect to this type of relay in the NO position? And if not does anyone make such a wireless motion sensor receiver combination that will run a hard wired door chime?


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RE: wireless motion sensor and form C relay

"Being an "old timer" I'm only familiar with electromagnetic relays..."

The output is a set of relay contacts.
"Dry contacts" means they are not mercury whetted and may have problems with low voltage (less than 5 V or so DC) or low current (less than 1 mA or so).
These are called 'dry circuit conditions.'

The typical 24 VAC on a doorbell is high enough voltage and the currents normally large enough (many 10s of mA minimum) to prevent dry circuit conditions from causing problems.


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RE: wireless motion sensor and form C relay

Dry contacts means that no voltage is present at either terminal. It is designed to switch a seperate source of power


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