I'm replacing the doorbell in the house I just moved into. Currently, there is some Aiphone setup (never heard of this). What I do know is that the current doorbell camera has two wires (A1 and A2) that connect to the base unit. The base unit is powered by an adapter that is plugged into the wall.

My goal is to replace this with a Nest doorbell and a chime. I'm not clear on what I need and a bit confused.

I think I can get a plug in transformer to power a chime that I can buy (essentially replacing the current power adapter), but not sure where the A1 and A2 wires from the front door are supposed to go. I figure that A1 is the power.

Any simple diagram or explanation would help immensely. Thank you.

1 Answer 1


A typical doorbell circuit is wired this way (in North America, that I've seen) :

doorbell wiring power supply to button to chime

The power supply can be a plug-in transformer or a wired-to-an-electric-box transformer. 16-24V ac comes out on one wire of a usually two-wire thermostat-style cable. The one wire goes to the doorbell push button. Then it returns to the electromagnetic chime, then back to the transformer. Pushing the button completes the circuit, making the ding-dong noise.

This diagram shows the same chime with a video doorbell device:

video bell circuit chime has passthrough device added

The button at the door is replaced with the video doorbell. There is a passthrough device that comes with the video doorbell, which is wired in parallel with the door chime. The passthrough device allows sufficient power to get around the chime to run the video doorbell.

If your doorbell is not the usual electromagnetic chime that goes in a circuit like this (it plays multiple notes instead of only one or two, or sounds like a computer playing MIDI tunes instead of struck metal) consult the video doorbell's manufacturer.

Regarding your Airphone, I would not re-use any of the equipment with it: the front door part, the base unit, or the power supply. Get a new doorbell transformer, electromagnetic chime, and video doorbell. If the wires between the base unit and door phone are basic two-wire thermostat-style cable, you might be able to re-use the wire. Otherwise, run new thermostat cable.

  • In this diagram, does it matter which of the A1 or A2 wires goes to the transformer vs the chime?
    – Marc J
    Commented Sep 5, 2023 at 7:26
  • A1 and A2 are designations of the Airphone equipment. We don't know what kind of voltage/current/power/ac-vs-dc the Airphone equipment uses or generates, so it would not be wise to re-use it. With a standard doorbell transformer it does not matter which screw the chime wire or the pushbutton wire attaches to. The transformer output is AC, so no polarity is required. Commented Sep 5, 2023 at 11:48
  • I'm a bit confused of how to power the new doorbell then. Here is my current setup so I don't see any other ways to power. Will I need to run a new wire? This looks like an ethernet wire to me. imgur.com/Rb7vmDX
    – Marc J
    Commented Sep 5, 2023 at 21:02
  • Yes, that appears to be Ethernet cable repurposed. If the orange pair are continuous back to the other end, you can use that pair. Attach solid orange to one transformer screw and one videobell screw. White/orange to the other videobell screw and one chime screw. A third wire (or more white/orange) from the other chime screw to the other transformer screw. The passthrough device straddles the chime screws. Commented Sep 5, 2023 at 21:09
  • Thank you so much. They makes sense to me
    – Marc J
    Commented Sep 5, 2023 at 21:19

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