Introduction
Doorbells are not just for alerting us when someone is at the door anymore. Nowadays, they come with various musical tunes to create a welcoming ambiance, from classical symphonies to catchy pop melodies. But have you ever wondered what goes into making a musical doorbell?
In this article, we will dive deep into the technical aspects of a musical doorbell circuit, discussing the built-in stages, the push-button operation, and the different melodies that we can play. So, get ready to discover the inner workings of a musical doorbell and learn how it brings music to our doorstep!
Hardware Required
| S.no | Components | Value | Qty |
|---|---|---|---|
| 1 | IC 1 | 7805 | 1 |
| 2 | IC 2 | UM3481 / UM3482 / UM3483 / UM3484 | 1 |
| 3 | Transistor | BC639, BC640 | 1, 1 |
| 4 | Diode (Bridge Rectifier) | 4 X 1N4001 1 X 1N4001 | 5 |
| 5 | Speaker | 8ohm 250mW | 1 |
| 6 | Switch | – | 3 |
| 7 | Polar Capacitor | 2u2, 100u, 470u | 1, 2, 1 |
| 8 | Non Polar Capacitor | 1n, 47n, 100n | 1, 2, 1 |
| 9 | Resistor | 820k, 10k, 330k, 4k7, 100k, 180k, | 1, 1, 1, 3, 1, 1 |
| 10 | V. Resistor | 100k, 47k | 1, 1 |
Circuit Diagram
Working Explanation
The musical doorbell circuit comprises a musical chip and an AC to DC power supply with a voltage regulator stage. The musical chip contains several built-in stages, including an oscillator, frequency divider, drive ROM, tone generator, rhythm generator, timbre generator, modulator, run-off control, and pre-amplifier stage. A push-pull amplifier and a speaker generate the musical output. The frequency of the multi-tune doorbell is determined by resistors, a potentiometer, and a capacitor for the built-in oscillator stage. And the run-off speed is determined by a preset.
The chip’s internal modulator stage is optimized by a resistor and capacitor. While the pre-amplifier stage is configured like volume control with a resistor, a preset, and a capacitor. The circuit is operated by push buttons, with S2 functioning as a typical bell push button. The doorbell can play a sequence of all the saved tunes, a single melody, or a specific melody selected by pressing S1 and S2, with S3 being used to cycle through melodies. The musical chip UM3481 contains 8 Christmas carol melodies. UM3484 includes Big Ben striking one to twelve. UM3482 has pre-programmed melodies like “Frere Jacques,” “Happy Birthday to you,” and “Cradle Song,”. While UM 3483 includes melodies such as “The Last Rose of Summer,” “The Lorelei,” and “Wedding March.”
Final Words
A musical doorbell is a small yet intricate device that adds an element of fun and entertainment to our daily lives. The circuitry inside a musical doorbell is a perfect example of how science and art can come together to create something beautiful. We hope this article has provided valuable insights into how a musical doorbell works. Try out this circuit, and feel free to ask your questions.
