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Topic: Relay to close 120volt contact triggered by ground (Read 417 times) previous topic - next topic

jb_bak

Hi, can anyone help me figure out a way to turn on my porch light, that will be triggered by a ground. So when I ground, the light comes on, when I unground, it goes off.

Thanks!

Grumpy_Mike

You want to use a relay.
Wire up the relay through a transistor to the arduino.

dc42

Formal verification of safety-critical software, software development, and electronic design and prototyping. See http://www.eschertech.com. Please do not ask for unpaid help via PM, use the forum.

jb_bak

Its my ip cameras external outputs, i know not arduino related, but you guys are smart. Ill house the relay in the light, where ill also have a 12 volt connection if that helps

dc42

In that case, it would help to know the specification of the IP camera output. As you are talking about "grounding", I presume it is an open-collector or open-drain output; but it may or may not be rated at +12V.
Formal verification of safety-critical software, software development, and electronic design and prototyping. See http://www.eschertech.com. Please do not ask for unpaid help via PM, use the forum.


dc42

It's an open-collector output, and it looks like it's designed to drive a relay already, without using an external transistor. So connect the coil of a 12V relay between the output and the +12V supply, and connect a flyback diode in parallel with the relay coil.

If you look on page 145 of the manual, it should tell you the current sink capacity of that output.
Formal verification of safety-critical software, software development, and electronic design and prototyping. See http://www.eschertech.com. Please do not ask for unpaid help via PM, use the forum.

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