Here is an AC triggered Multitone, polyphonic doorbell. It gives eight melodious tunes for 2 minutes. On each press it will give a new tone which will continue till the melody is over. The circuit is too simple and battery operated It uses the popular melody generator IC UM3481.
The circuit uses the popular melody generator IC UM3481. It generates music tones like Jingle bell, Santa clause is coming, Silent night, Holy night, Joy to the world, Rudolph, Red nosed reindeer, Merry Christmas, O come, All Ye faithful, Hark and the herald angel sing. UM 3482 generates 12 music tones. Capacitor C1 and resistor R2 are the oscillation components. Pin1 can be triggered either by DC or AC. Here low voltage AC is applied to the trigger pin 1 through R1 and D1. The circuit works off two pen cells which last for more than one year
Caution: The circuit is connected to high volt AC. Do not touch any parts when it is powered to avoid lethal shock.
s:electronicsuite.com,
EmoticonEmoticon