The doorbell that plays WAVs

When the doorbell to our company office broke, my boss half-jokingly suggested we replace it with one that could play WAVs.

We didn't find a doorbell with the capability of playing WAVs ... but we found one that had a built-in microphone and could record its own chimes.

Armed with a soldering iron, my colleague Mark and I set about bending Funki Tech to our will.

The device

Our doorbell consists of a loudspeaker, a microphone, some circuit board, a controller board, batteries and probably some other stuff.

The bell

Tracing the cables from the microphone to the controller board revealed that the input signal was connected by two standalone pins while the system was driven by the larger set of pins to one side.

The circuit

The plan

We theorised that by connecting the headphone output of a PC to the input on the controller, we could get the doorbell to record an arbitrary waveform.

Connecting things together

I bought a 3.5mm jack and a metre of dual-core wire from Maplins. Total cost: 79p.

Mark then soldered them together to make a connector.

The connector

Finally we shoved the other end of our cable into the microphone input.



I'd like to present a "Finished works" image at this point but sound doesn't translate all that well on the web. Suffice to say that by linking our cable to my PC and playing back a WAV I was able to coerce the doorbell into playing the Imperial March from Star Wars every time someone comes to the door!