Triggering Alexa tone/notification using NO/NC relay or 12v DC output from RE-4K Plus Receiver (driveway alert system)

Ok, I am a newbie with all this smartthings stuff. I searched for hours but couldn’t find a solution I could understand. So I am hoping that I can get some assistance and possibly add some useful content for anyone looking for a similar solution. I did see some topics about using a 12v DC output from an alarm panel and hooking that up with either a stepdown converter or a relay to a Z-wave door or water sensor and using that to trigger events. But that was about as detailed as those threads got and that was from a few years ago so I thought I would post this again and see if there were any known 12v DC triggers out on the market yet.

Here is the situation. Our driveway is on the side of our house and there is only one window facing it. If we are not in the breakfast room then we don’t get to see the driveway. We want to know when we get visitors whether it is a delivery driver that doesn’t bother walking around to the front door or a guest. So I found the metal detecting Dual 4k Plus driveway alert system. This kit comes with 1 DAPT-4000 and one RE-4k Plus receiver. The receiver puts out a tone when the sensor detects a vehicle. However, we have a large house and a large outbuilding. I could get several of the receivers and put them all around the property but at $60-$75 each that would add up fast. The receiver also has two NO/NC relays and a 12VDC output terminal. So I thought why not use the Alexa devices to send a notification/doorbell tone to all the dots and echos we already have spread around. Unfortunately, the receiver is not a smart device. So I am looking for some way to use one of the relays or 12v DC output to send a doorbell type tone to our Alexa devices.

So I know how to solder and can do some circuit hacks/bending if needed. I just need to follow a plan to do it. I am also not quite sure how to use a water sensor to send a tone to all the Alexa devices. I searched Amazon for water sensors that work with Alexa and didn’t see any sensors in the results.

Does anyone know of a device or somewhat simple solution that can be used?
Can you walk me through the basics of how to do it?

If I understand what you’re asking for, assuming that you also have SmartThings (this forum is for people who are using the Samsung SmartThings ™ home automation platform), this is easy. :sunglasses:

  1. Connect the driveway sensor to any open/close sensor that works with SmartThings.

See the following FAQ for some typical devices of this type. (The topic title is a clickable link.)

These devices will then show as “open “ to SmartThings when the relay is activated. And smartthings will pass that information along to Alexa.

  1. when that sensor shows as open, use that as the
    “When this happens” in an Alexa routine (not a SmartThings routine)

You can have the action in that routine be having any or all of your Alexa devices make a specific announcement. Or you can have them play from a set of available sounds, including several different chimes. You create this routine in the Alexa app.

So it should be very straightforward.

If by chance you aren’t using the Samsung SmartThings system, you would need to find any standalone Wi-Fi open/close sensor that works with Alexa that can act as a dry contact and you should get the same result. I just don’t happen to know specifications for those since, again, the assumption is that all of the questions and answers in this particular forum are for people using Samsung SmartThings.

Alexa routines can be triggered at the present time from an open/close sensor, a motion sensor, or a lock. So that’s what you need as the trigger.

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Than you for the reply. Yes, I have the Samsung Smartthings Mesh WiFi hub system.

I also just found this video showing how to hack a door sensor:

So I am thinking I can do this with the door sensor but instead of hooking the wires up to the contact panel as shown in the video I could just hook the wires up to the NC contacts on the RE-4k Plus receiver. I should be able to directly connect the wires to the relay contacts, correct? Then when the receiver gets the signal from the driveway sensor it will open the relay contacts and the door sensor will read that as open and then I can set up the push notification from that, correct?

The physics are different in that. The water sensor isn’t carrying a charge.

Just buy a device which is designed for this purpose, that is, which already has dry contact points in it. It will be way easier and safer.

Also, Wyze sensors don’t work with smartthings. So, as always, the first rule of home automation applies: the model number matters.

Check the community FAQ for the list of devices that are already designed to accept external input and you should be good to go. They will have internal screw terminals, so you don’t have to solder anything or take the device apart the way the guy did in the video. You just open the case, and attach the wires.

Btw, it’s hard to beat the zooz zen17 for this purpose as long as you’re on the North American frequency.

Right, you couldn’t hook it up to the 12v DC output but the built in relay shouldn’t put a load on that circuit. That is what a relay is for, right? I was using the video as an example not necessarily saying to use the Wyze contact sensor but any contact sensor should work pretty much the same, physically speaking.

So you could do the same thing with this Samsung Smartthings contact sensor:

The Zooz Z-Wave Plus Universal Relay would work. I could just connect the 12v output to the Zooz relay. It says it needs a custom device handler to work with Smartthings. How hard is it to set that up?

Use an EcoLink Z-wave tilt sensor. It has a set of contacts that can be connected to the NC/NO contacts in the the driveway controller. It shows up in ST as a contact sensor, so it can also trigger Alexa Routines. And it is less than $12.


Wow, the EcoLink Z-wave tilt sensor looks like exactly what I need and it is so affordable. I will give it a try and report back. The driveway sensor will be coming in soon. Thanks.

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When I ordered the TILT-ZWAVE2-ECO a few months ago it was only $9 and the sent me the more recent version TILT-ZWAVE2.5-ECO.

Also it pairs with the new stock Z-Wave Sensor Edge Driver, so it will continue working with the new ST architecture

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This is the tutorial I followed. I have notifications sent to my phone via SmartThings, and Alexa announcing “someone is here”.

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