Upgrade an old Intercom to Open the door

Well, although the section is DIY. But I am a new comer and I need help from the expert.

I live in a rented and old apartment, we have an old intercom similar to the one in the attachment, which allow us to open the main door using the button.

Is there a guide that explains how can I upgrade this device with a ZigBee compatible connector and then I will use OH to open the door.


Lot’s of threads to read on this or similar topics:

Thank you @sihui. Although, I did the search and couple of the above appeared but found different than what I need. Regardless, I will go through all of them to understand more.

I admit, I have no experience neither OH nor wiring. Nevertheless, I will try.

Thank you again.

“Real” Zwave door locks have additional security features compared to ordinary zwave relays etc.
You should consider the risks before hooking up your lock.

What I thought (as layman) that I will only need a connector to be soldered in the highlighted panel (attached) which looks like the one responsible to open the door lock, then use OH to send a command to connect.


You need to find out what signal is on those connector. Dry contacts without any voltage? Then you could use a Zwave Universal Binary module. Or a Window/Door sensor with external contacts.
Or do you need a relay to drive any voltage to it?
Lot’s of things to consider and unfortunately your are not giving much information to answer your questions.


This device works by wifi and is controlled with the ewelink android application, which works as a Wi-Fi switch and is small, you could place it inside the phone’s case, you only need a 220V or USB 5V power supply

You are of course correct - hacking an uncrypted zwave device is not very difficult.

But realistically, the Venn diagram of (1) people able to do this and (2) people interested in robbing ordinary homes looks like two separate circles.

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People do make decisions about security vs. convenience every day. Sometimes they have enough background info to make an informed decision.

So far we’re doing good work, highlighting both potential problem and risk evaluation :grinning:


I agree. It’s always worthwhile to highlight potential risks when we’re talking about automations that prioritize convenience over security, just to ensure that others who read this thread are aware.

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I completely agree with this statement.

But, unfortunately, it’s only true right now.

Who would have thought that people would start stealing cars using a signal booster to make the car think the keyfob in your pocket in your house is actually next to the car and allow thieves unlock and steal the car? Five years ago the venn diagram of people who want to steal cars and have the ability to perform such attacks were separate circles. Now for around $150 you can buy a device off eBay to do this and it’s become routine.

For now there is no problem. In the future who knows. Maybe hacking zwave locks will become routine. Any risk decision needs to be revisited as the threat environment changes.


Well that is a truly excellent, and troubling, response…

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Sorry, I was away for sometime. Busy with work and study.

I made a mistake in my previous post when I hilighted the lines which should be connected to open the door.

Today, I took a screwdriver and open the intercom and found that the two highlighted metal (attached) are the responsible to open the door when they are connected.

What kind of switch, button, etc shall I use to do it.

PS. Security is not a matter here, in fact most of the time the door is open, but there are times when it is closed and it shouldn’t be. So, I want an easier way to open. For example, I am at work and I have a parcel to be delivered. How can the courier enter?

Thank you in advance.

This is my first DIY, if you think I missed some information, I would appreciate your guidance.

It looks like you need a (solid state) relay to simulate pressing the black button. This relay can be driven by any kind of wifi enabled switch device that has at least one output pin.

BTW, your picture is not very sharp when enlarged. Can you provide a beter one?

Thank you for this hint. I will Google it and find out.

The previous photos were a Google search result.

Attached photos are the exact device, took photos myself, which looks same.

It’s just a simple bi-metal switch, a simple relay should do it.

Quickest, easiest way would probably be to bridge the two contacts using an opto isolator. You don’t need the driving current for a relay or have to worry (very much) about any voltage on the device side. An opto isolator and a resistor are all you need plus a (analog or digital) output. I’ve retro-fitted quite a few devices around with the house this way. Also requires much less space than a relay - you could get it in to the intercom with room to spare.
I have a tendency to use 4N35s but the only specifications you’re really after in this case are the driving current and the isolation itself.



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Those contacts may carry nasty spiky AC current if they switch the door lock solenoid directly.
An old-fashioned electromechanical relay is really the best bet when dealing with unknowns.

Hi Alahdal,
if you want a quick and easy solution, then you could use a cmos 4066 quad bidirectional switch + ESP8266.

What i have done is:
OpenHAB<–MQTT–>ESP8266 (running ESPEasy)<–GPIO–>4066 Chip<–soldered to your device.

CMOS 4066: https://www.ebay.de/itm/5x-CMOS-4066-Schalter-4-fach-digital-analog-C-MOS-IC-DIP14-/311014564191

Some infos on how to connect: https://www.youtube.com/watch?v=okBDs69tbWU


Thank you everyone for the contribution and support. I have gone ahead and purchased the below item. I hope it is a wise decision.

ESP8266 ESP-01S 5V WiFi Relay Module

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