Door phone w/lock opener

Zab

Attached you can see the internals of a door phone with the buzzer in the upper left not working.

Wires come in from the wall in the centre, and the cable going to the right is towards an actual house phone. I assume the gist of it is that it's "stealing" power from the actual phone line to run the buzzer/door/audio.

Assuming the above is true, can anybody recommend a replacement buzzer as I'm not sure which to get (I've had a look at the one in there and its problems seem internal).

Also, how complicated would it be to rig up a wireless doorbell at this point, where instead of buzzing the buzzer it "presses" the wireless doorbell's transmitter unit. I'm thinking this might be a pretty simple job with ... a single transistor?

Chet T16

Single NPN across the wireless doorbell switch with the gate connected to the existing buzzer wiring. I've done this before without a common ground and it worked fine.

Zab

Cheers Chet. This oughta do it?

Chet T16

That'll work, very over spec'd though!

Zab

He posts for free so it's a bit much of a muchness vs other options on ebay. Thanks again Chet.

Zab

note to self: check size of components before purchasing and make sure they're wider than 2mm unless that's actually required.

Thanksfully they included some free BCU83s which will hopefully work.

Chet T16

I had assumed you had measured to replace a small switch!