Melody IC

Hello, I'm a student in Korea. Recently, I learned that there is a Melody IC and I was curious about the internal structure, but I just found out that there's a complicated circuit inside and nothing found...

  1. Do you have any links or data on the internal circuitry of melody ic?

  2. Do the sound(tone?) be adjusted by resistance and the sound length be adjusted by a transistor or capacitor? I'd like to know how the melody ic works...

  3. If I study the principle of melody ic, is it possible to make it on the breadboard without Arduino? (I'm talking about making such as DIY melody ic)

This may sound strange, but please help me...

Creating one tone or even three or four tones on a breadboard might not be difficult. Here's one circuit for creating one frequency:

Don't know though, how you would create two consecutive tones. As I see it, as soon as you want just a few consecutive tones with distinctive pitches and lengths (to form a melody), you really should use microcontrollers. If you wonder what lies inside this chip:

... which plays only one melody ("It's a Small World"), I bet it is a microcontroller construction with its own integrated crystal for keeping the time, its own ROM holding the melody, its own CPU like part reading and executing a simple program inside the ROM. Creating a chip playing another tune means only changing the part of the ROM, where the melody is stored, not inventing from scratch another IC chip with three legs.
If you really want to create whole melodies without the microcontroller, just with resistors, transistors and capacitors (and the piezo buzzer), I guess there are no breadboards large enough. Each soundable tone would have its own set of components for creating the right pitch and length. And when ending the tone, the circuit would trigger the next circuit for the next tone.

Do you have a link to the "Melody IC" that you found?

Or if you want to build a circuit yourself what do you want it to? What features and specification must your "DIY melody ic" have?


There is an IC called a Top Octave
Generator that produces a one octave
chromatic (equal tempered) scale.

Thanks to Johan_Ha for a kind and useful answer!!!!!

I learned many things from your answer...

Maybe I should study hard to make my breadboard melody ic

Thanks once again.

BTW the melody chips used in cheap toys does not use a crystal for timing, they use an RC oscillator. A "proof" of this is they change speed and frequency considerably with supply voltage shift (typically they are much slower with near dead batteries).