Melody Generator Circuit

This is a simple project using the IC UM66. UM66 has an inbuilt beat and tone generator. This IC, with its three legs, looks like a transistor. This IC has many versions for playing different songs/beats. This project is suitable for beginners as its circuit is very simple.


 The  UM66 series are CMOS IIC’s designed for using in calling bell, phone and toys. It has a built in ROM programs for playing music. The device has very low power consumption. Thanks for the CMOS technology. The melody will be available at pin 3 of UM66 and here it is amplified by using Q1 to drive the speaker. Resistor R1 limits the base current of Q1 within the safe values. Capacitor C1 is meant for noise suppression.


  • Power supply  must be between 1.5V & 4.5V .Do not exceed 4.5 V.
  • Speaker can be driven with external NPN  transistor.
  • Melody begins from the first note if power is reseted.
  • Assemble the circuit on a good quality common board.
  • If transistor HE8050S is not available use any NPN transistor like BC548 or 2N2222.


  1. Capacitor 0.1uF – 1 nos
  2. UM66 IC – 1 nos
  3. Speaker – 1 nos
  4. Resistor 4.7k ohm – 1 nos
  5. Switch – 1 nos
  6. Power supply – 1.5-4.5V – 1 nos
  7. HE8050S – 1 nos

Circuit Diagram

Melody Generator Circuit using UM 66 IC

UM 66 IC – Data and Specifications

UM 66 Data Sheet with specifications
UM 66 Data



  1. What can be done to strengthen the multiplier circuit? Amplification؟؟؟

  2. sir,please give me working of um66 ic and block diagram and pin identification in ic

  3. can ic555 timer be used in water level indicator with alarm to generate tone? if yes, can you help on how to substitute it with icum66.

  4. I have searched for icum66 in the market but cannot find one. please can i get a substitute?

  5. Seetharaman

    Hi Sunil It is manufacturer’s product ID. C1 is used to decouple power supply to avoid inter-modulation between output and IC. If you get a distorted sound you can add 100uF electrolytic capacitor in parallel to C1

  6. sir , i want that what does 66 indicates in UM66.
    Is capacitor helps in sound suppression in this circuit?

  7. sir, i want to know about the purpose of capacitor in this circuit and why we connected capacitor in parlell of circuit give reason

  8. Hello
    I cant get that circuit in digikey. Where can i buy
    Which is the nte replacement

  9. please sir can you give me informatio regarding working and construction for my project

  10. sir, i’m student i would like know working and storing own music by using UM 66

  11. twits4twats

    is it possible to store our own created music into um 66 if yes , how to store it… what circuit can be used. if not can any one tell me a nice way to “Design a circuit to create, play and save ringtones”


    Like Admin has stated, UM66 is designed and manufactured with those melodies. You can not reprogramme it. You need a voice recorder circuit interfaced with a amplifier circuit.

  12. is it possible to store our own created music into um 66 if yes , how to store it… what circuit can be used. if not can any one tell me a nice way to “Design a circuit to create, play and save ringtones”

    • admin

      It is not possible to store our own music in UM66.
      I will add a voice recorder circuit soon.

  13. Seetharaman

    UM66 is a 3 pin melody device. once the supply is given to pin 1 & 2 it will give continuous audio out put at pin3, which is not sufficient to drive a loud speaker, hence an additional direct coupled amplifier is added to drive a small speaker.

  14. abdulsalam

    i want the electronic copy (write up document) of this circuit by friday to complete my project work. it will help if you guys will sent every thing about this circuit

  15. Dear sir,

    could you forward me a 30second sound circuit that activated by another speaker out(alarm clock)