Adding a switch/trigger to control a front-gate lock (12V)

Hi All,

This may not be the right section, but my gut tells me I could solve this with an ESPHome device.

I’ve got an existing home doorbell setup, it has a screen in the house, two-way mic, video, controls the front door gate lock. Wiring diagram below (Note: I only have a single outdoor lock relay / camera/microphone).

I’ve got a big gap behind the wall, I was hoping to cut-in a ESPHome (or similiar) so it could send a trigger to the lock-relay to unlock the front door. That way when I get home, I can simply trigger the front-gate unlock remotely and let myself in.

Would love some ideas on how I could achieve this with my setup, i’ve looked and couldn’t quite find anything that might work. I also spoke with Panacom (my provider) and they sent me all the specs but then tried to up-sell me a new multi-thousand dollar upgrade to my entire system.×143mm)V2.0.pdf

Hi Mitch,

Unless you are lucky enough for the original installer to have used a cable with more than the 4 wires running from the internal to external units then I think the only way to do it is the following:

At the external unit:

  • Join onto the +12V and GND wires and run these to a DC-DC converter and set the output to 5V.
  • Use the 5V to power an ESP and relay such this.
  • Wire the existing lock output from the external intercom unit to an input on the ESP via a voltage divider circuit such that the ESP input only receives a max of 3.3V.
  • Wire the existing lock such that the existing 12V goes to it via the relay controlled by the ESP.

You could use values of 10k and 3k6 for R1 and R2 respectively.

(I’ve used Aussie links because the few dollars you can save getting things from China is not worth the 2 month shipping time right now)

Don’t use the shit software shown in the datasheet for that ESP, just use ESPhome. It would be a basic code. You could go a couple of ways here:

  1. Just have the ESP energise the relay (and lock) whenever it gets an input from the intercom unit.
  2. Have the ESP only energise to open the lock if a HA boolean is set.

Either way you would also have the ability to open the lock from HA independently of the intercom unit.


Thank you so much, unfortunately I checked and they only put in a single 4-core cable.

I’ve placed an order for all those parts and am super excited to get it installed. Thank you so much sharing this! Will let you know how it goes and i’ll make sure to share my experience with others for the next person!

I’m planning to go option #2 because I ultimately want to switch-out the intercom for a Google Nest / Amazon Ring so I can let guests into the yard area when I’m not nearby. Does that impact the wiring diagram if I remove the existing intercom?

Not really, the ESP simply won’t have anything wired to it’s input. You will still be able to operate the lock via HA.

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I should have mentioned this earlier but for this to work you will obviously need to have wifi signal to the ESP at the gate.

My gate doesn’t have a wifi signal, i was planning (hoping) to put this in the wall behind the intercom video panel.

This was why I was hoping you had a couple of spare wires running out to the gate. Without them you won’t be able to to it.

How far from the house is the gate?

Ahh, i understand now. The gate is ~30m from the house, its got all sorts of accoustic dampening and sheilding which destroys my wifi signal. I’ve got a mesh set-up and it hardly penetrates the house. I might just install another wifi-node outside.

Feeling like my current set-up may have to continue without the automation.

I’ve got an existing home doorbell setup, it has a screen in the house, two-way mic, video, controls the front door gate lock.

You say you can open the gate from the panel in the house but this function is not show in the diagram provided.

Can you confirm that this possible with the current system.


That’s a good point that I had overlooked. I’ve now opened the manual and see that the lock in controlled by a button on the front of the internal unit. Since this is by way of a physical button then you could wire the ESP’s relay to that button to simulate a press.

Thanks for update, I assume in that case I am simply following a wiring along the lines of this:

Not quite. You will create a binary_sensor using GPIO though. Better off just using the official ESPhome docs.

You will need to find out what voltage is switched across the lock button on that internal intercom unit. Given that the rest of it runs 12V this is possible but not guaranteed, it could be lower like 5V.

Once you know the voltage you simply use the same voltage divider circuit I drew above to get 3.3V to the ESP input pin.

Thanks so much for updating the wiring diagram, i’ll go grab out the trusty multimeter and find out the voltage. super excited to tinker again with this and can’t wait.

Really appreciate the link to the official ESPHome docs, this makes a lot more sense.

No worries. If the switch is switching 12V then the resistor values stay previously stated.

For the power supply side of the wiring to the ESP just keep it as per the first sketch so you can use power from the intercom.