DoorBell circuit using UM 66 IC

admin November 9, 2018 29 Comments

Doorbell Circuit


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Melody Generator using UM 66

Door Bell Circuit Using NE555


The main objective of the doorbell circuit is to convert electrical signals (input) into audio signals (output) with a single press of a switch.

The circuit given below is a modified version of the Melody Generator Circuit, whose link is given above. In the previous circuit you had to keep the switch manually pressed for making the IC play the full music.

Here if once the push button is pressed Capacitor  C1 is charged and the transistor Q2 will keep the IC playing the music till it ends. The time for the IC to play depends on discharging time of C1 which can be set by R1. Set R1 to select your time, whether full tone or a part in one press. Transistor Q2 drives the speaker. Pin 1 of UM66 is connected to the base of Transistor Q1 (BC548), so as to amplify the signal to drive the 8 Ohms speaker (K1).




The IC UM66 is a melody generator CMOS IC and can be found in sound generating objects like doorbells, musical toys for kids, telephones, intruder alarms and so on. The IC has 3 pins with terminals GND (1), Vcc (2) & Melody Output (3). The tones are generated by the corresponding electrical signals at Pin 3. The IC works on a supply voltage range of (1.5-4.5) Volts. This IC can be used in small circuits as it consumes very less power. The IC will reset after a tone is played, and will start playing from the beginning. All you have to do is reset the IC using Switch S1. The IC does not require any new components to generate the audio signals. IC has a beat & tone generator that is already built inside. The time base for it is an in-built oscillator.

The tone generator produces a particular frequency, that is the oscillator frequency factor. The beat generator has 15 different beats, out of which four of them can be selected. The tone is generated using a 62 notes ROM. Out of this 4 bits control the scale code and 2 bits are used for the rhythm code.

Different tones are available with different versions of the IC. Some common tones are “Jingle all the way”, “Santa Claus is coming to town”, and “Christmas song”.

Doorbell Circuit Diagram with Parts List

Door bell circuit

R1100K POT
Q1, Q2BC548
S1Push Button Switch
K18 Ohm Speaker
B13 Volt Battery


  • Do not give more than 4.5 V to UM 66.
  • POT R2 is not necessary and can be bypassed. But if included you can set the loudness.

We have many other Tone Generator circuits that you may like take a look:

1. Tone Generator

2. High Power Siren Circuit

3. UJT Organ Circuit

  • January 31, 2013

    how can i build this circuit on breadboard?please send reply show build circuit on breadboard or pcb.

  • January 31, 2013

    how can i build this circuit on breadboard? please show circuit on breadboard and on pcb also.

  • sushil
    January 24, 2013

    What does the meaning of 3 on 100k & 10k pot. What value should I place in these two pot.

  • srinivas
    November 2, 2012

    how does R1 vary the time of charging of c1..
    is it directly or inversely proportional

  • December 15, 2011

    I get good help

  • ranjith
    November 4, 2011

    thank u so much for u r valuble information

  • zaid
    October 24, 2011

    i want its complete description
    an any one help me ?????

  • seetharaman
    July 12, 2011

    Hi Kiran see the notes kindly delete R2 and connect speaker to + direct, without pot.

  • ramya
    July 12, 2011

    i saw the circuit it was good but i want to make reverse horn of car.please send me a simple and with loud sound because i am just a beginner of electronic.

    from ramya

  • kiran
    July 12, 2011

    i made the circuit but from the 100k pot fire sparks are coming out.please can you tell me whats wrong in the circuit.

    from kiran

  • keshav bargaje
    April 6, 2011

    i want description about music bell circuit diagram can you send the same on my email id

  • Nirmal vyas
    September 18, 2010

    i want 36 v input operated, 2-3 minit timer musical pcb digram want with parts list. can u send me on my mail id

  • seetharaman
    September 13, 2010

    Hi Maina try for 3481 series ICs HT3820, 4822, AM993-9A etc. any melody generator IC which can work from 2.7 to 5 volt can be used

  • maina
    September 13, 2010

    i cant find um66 in kenya,what equivalent ic would u recomend 4 me

  • seetharaman
    July 10, 2010

    Hi Nishanth you are right Pin no1 common, 2 supply and 3 output.
    This IC is a basic CMOS ROM with built in melody, which is prefixed and cannor be changed.

  • Nishanth
    July 9, 2010

    I need some explanation of the circuit. As far as I know the output of the IC UM66 is from 3rd pin but it is taken from 1st pin. So pls provide some explanation. Pls…

  • omongin ronald eric
    June 6, 2010

    am to get a project for my final year. i need a suggestion of what kind of project i can make am studying a diploma in Telecommunicatiun Engineering can anyone help pliz

  • April 23, 2010


  • Zach
    January 3, 2010

    I can’t find UM66 in Singapore. I’d appreciate your recommendation of an equivalent chip that can simply replace it in the same circuit. Thanks in advance.

  • Anu
    October 6, 2009

    I am building a doorbell for deaf people.A device will be tied to the deaf person’s hands…When the doorbell rings the device should vibrate so that the person knows somone is ringing the bell .Could u tell me a solution for this

  • August 23, 2009

    i feel there must be description over the diagram for better understanding. if it is their i didn’t find.

    July 30, 2009

    door bell

  • vignesh.s
    June 16, 2009

    this circuit has very low sound…!
    \do have any solution

    • admin
      June 16, 2009

      have you adjusted the potentiometer R2??

  • shankara
    November 29, 2008

    Good Info , thanks for sharing..!

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