Inspired by a code snippet found on internet, recently I have designed one simple but versatile Musical Doorbell with Over Door Light circuit using the 8-Pin microcontroller PIC12F675. This is a fascinating door bell with 4 different melodies, plus a switch output to control an electric lamp (as an overdoor light) in the external world. The main circuit is ultra compact and can be powered from any 6V battery supply.
With a little skill and patience, you can easily enclose the whole circuit in a small plastic box with the bell-push switch (S1) fitted in front of it. Link to the overdoor light (L1) and piezo-speaker (PZ1) can be extended from the enclosure using suitable length of wires/cables.
HIGH VOLTAGE, LETHAL POTENTIALS ARE PRESENT IN THIS CIRCUIT