# Control the door release function of an apartment intercom

I have a Aiphone GT-1C system and am trying to see if its possible to trigger the door release feature for my apartments intercom system.

    IN  | OUT | IN | OUT |
----+-----+----+-----+
R R |R R  |B B |B B  |
1 2 |1 2  |1 2 |1 2  |
23.4v|23.4v| 0v | 0v  |


I measured the In and Out for R1/2 at 23.4v and 0v for In and out of B1/2. When I press the door release button (when its off not being called) all the pins go to 23.4v high. This leads me to believe that they are sending data over wire. I do have an oscilloscope that I could use but I feel like if it got to that point it would be over my head.

I emailed tech support asking if they had a dedicated door release pin and they responded with this:

An option switch dry contact closure can be used when connecting a dedicated strike circuit to the gray and black wires of the 6-pin option cable.

The door release button on the GT-1C triggers the Form C contact built into the back of the speaker module of the entrance. The tenant would need to press the Option button (the icon looks like a laptop monitor) to unlock their own unique door.

I was confused by the response. From what I understand dry contact just means it's volt free meaning its a secondary relay or something. But I don't understand the part about the dedicate strike circuit.

### With the information would it be possible to trigger the door release using a some kind of hardware (microcontroller, switch, etc.)

• The response is trying to tell you how to add an electric strike (door lock) to your apartment and to use the option key to control it. It is not very clear from your post, I think instead you might be asking how to open an existing door lock at a common entry. For that, the simplest way may be to take the front off and hack in a relay contact to the door release button. – rioraxe Sep 14 '16 at 0:44

The door strike is the bit on the frame that the lock latches into.

https://en.wikipedia.org/wiki/Electric_strike

What I get from this badly worded instruction sheet is that if you want an electric strike, so you can operate the door release remotely you route the power supply to the strike (which must be within the specified parameters) via these two pins. Internally there is a normally open contact activated by the "option" button which will complete your circuit and activate your strike (that is it will release the door).

So you will need to supply an electric strike (if not fitted) and its up to 24V supply, and all the intercom does is activate it when you press "option". So if you don't want to have the "press option" feature, just ignore that and create your own entirely independent circuit with a strike, power supply and switch.

It was clear to me.

• In low current relays they have to be non-oxidizing and free of big arcs.
• Mercury bulb "Wet contacts" ( bounce free )
• Gold-plated "Dry-contacts"
• (always rated < 2A to prevent gold plating damage)

Door Strikers come in both AC and DC

. V . . I

• 12V 0.44A or
• 24V 0.23A
• (6 watts)

simulate this circuit – Schematic created using CircuitLab