Monitor circuit and close a "dry contact" after certain time?

Projects General Guidance
1

Totally new to Arduino, looking for feasibility help here.

I want to build something that will monitor a circuit that has a pump on it (well water), and if the pump is on for some period of time, I want it to close a contact that will be used by another magic box that will call me.

I think I can figure out the "is the circuit on for x minutes" part, but I don't know about the dry contact output. Is this just a relay that would be closed/opened accordingly? Or what would I need on the output side? See below about it needing to be "dry contact, no voltage".

The magic dialer box says this:

Any sensor or alarm device that opens or closes a dry (non voltage) contact can be connected to the auxiliary alarm input.. The auxiliary alarm input cannot accept any device that sends voltage through the contact wire.

Thanks for any help.

Tom S.

2

They mean like a switch, it makes contact or it doesn't.
Like many switches for a house alarm, those are often reed switches with a magnet in the door or window. The reed switches are NC (normally closed) or NO (normally open).

A relay, or reed relay can be used. The ouput of the relay is connected to two wires of the auxiliary alarm input. Those two wires are not connected to the Arduino.

3

Thanks - is there an arduino-compatible relay you might recommend that I could use for this?

Not being circuit-knowledgeable, is something like the following appropriate?

4

That is a relay module that need 5V. It is perfect for the Arduino and your alarm input.

I happen to like the small reed relays in DIL package. Some are only 10mA and can be driven directly to an Arduino pin. You do need two diodes to clamp the pin to 0V and 5V. I'm not the only one who likes them: Arduino Your Home & Environment: Working with Reed Relays