The circuit diagram given here is a simple melody generator. The core part of the circuit is the IC UM66 which is a CMOS type IC. One of the main features of this circuit is that in consumes only less power. This IC UM 66 consists of a read only memory (ROM) where program for playing music is stored.
The melody output is taken from the output pin (pin3) of IC UM 66. This output is amplified using an amplifier circuit based on transistor Q1 (HE8050S). This amplified output is then fed to the speaker. Resistor R1 is used for limiting base current of transistor Q1 and capacitor C1 is for reducing noise in output. A single DC power supply of voltage between 1.5 V and 4.5 V is used here for powering this circuit.
IC UM 66 Datasheet
- Use a good quality common board to assemble this circuit.
- IC UM 66 is specially designed for using in calling bell, phone and toys.
- The power supply voltage should not exceed 4.5 V.
- Use NPN transistor like BC548 or 2N2222 if HE8050S is not available.
- If power is made to reset, then melody starts from first.