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Step 7: Case Logic

Picture of Case Logic
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Doorbell Case Video: https://youtu.be/Bn1qj2Uvl0w?t=416

Base Unit Video: https://youtu.be/Bn1qj2Uvl0w?t=856

Once I'd proved that the code would work the next thing was to decide on a case for the project. I wanted it to be obviously a doorbell, but didn't like the idea of having a fully-connected Pi hanging outside my house for obvious security reasons.

What I decided was to split the project in two - to have a doorbell unit outside the house, connected to a Pi base station inside. There were a couple of good reasons to go in this direction:

- Fewer components to squeeze into the exterior case and be exposed to the elements

- Much better WiFi signal inside the house, with the added option of Ethernet

- Easier to perform maintenance & upgrades

- Secure my precious Pi 3B+ behind a locked door

Making the decision on the webcam was easy - one of my MotionEye security cameras has been running 24/7 for over two years using a Microsoft Lifecam HD 3000 and a Pi Zero so this was a logical choice - especially as it has an integrated microphone. Many other webcams work well with the Pi, and you could even use a standard Pi camera - though then you'd need a separate microphone to capture the audio.

The exterior unit was also a no-brainer, a 1986 Intercom! I bought a 3-pack of these retro devices a while back and only used one in 2017 for the Google Pi Intercom project so had spares handy - plus I was already familiar with its innards and was confident I could make everything fit.

For the interior base unit I considered just using a standard plastic project box, but with the local Maplin having closed down it wasn't so easy to choose a suitable match - so I decided to re-use some more old tech and fit the Pi inside an old cassette player. This worked out really well as there was plenty of space - and meant that the VU meter LEDs could display through the tape window, a convenient extra touch. I was also able to connect the cassette player's original speaker to the spare output on the Phat Beat - meaning the ringtone and speech would play inside the house as well as outdoors.

To connect the two units together I decided on 6-core alarm cable, as this is pretty thin and easy to work with, adding a connection block at each end.