Looking for a trigger switch device

I’m looking for a trigger switch, basically something which when an electrical current passes through, will trigger a signal to the hub. Like a motion detector but instead of the motion sensor triggering the signal it will be a simple current zap.

Since there are no driveway sensors on the market yet want to build my own. I’ll use an optical eye which when cut will trigger a relay which will send a current to that trigger switch.

Many people simply use a z-wave Magnetic Contact Sensor with external contacts. You simply need to close/open those contacts electrically (e.g. via dry contact relay) to change the state from Open to Closed. (i.e. don’t use the magnetic switch portion of the sensor, just the external contacts.)

No need to “monitor current flow” as that is much more complicated that simply opening or closing a set of contacts.

Here is an example where someone used one of these sensors to create a water leak sensor, as an example of what is possible.


Oh yes indeed that could do it, thanks for the suggestion. The main challenge will be to convert a 120 volts AC current to a 3V DC that the door switch works with.

Maybe on the same principle a could modify a z-wave light switch.

look into Guardline

I’ve seen this before but discounted it because I thought it was just a bell trigger.

I do see indeed that it has a 12-volt relay output which could be very easily reduced with a resistor and trigger a 3-volt magnetic door sensor.

That’s actually a very good option because the receiver has a long 500 feet range which takes care of ST hub limited range issues for long driveways, it is waterproof and can accept up to 16 sensors.

I think this is definitively a winner, so much easier than building my own optical detector. Thank you for the suggestion.

maybe i’m missing something, but why do you need the 3 volt magnetic door sensor? you would just wire the NO or NC to a door sensor or dry contact sensor that has external inputs. Then pair that sensor to SmartThings.

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You’re correct, I was just thinking about that actually.

3 volts is only needed to power the switch to communicate with the hub, I just need a relay to open or close the switch (which is what the magnet normally does on the door)

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I think a flood detector might be even easier to work with. All I need to do is making contact between the two electrodes. Unless they require a “permanent” contact rather than a short close/open trigger.