Doorbell Circuit


Related Posts:

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



  1. pradnya bhagat

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

  2. pradnya bhagat

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

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

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

  5. thank u so much for u r valuble information

  6. hey
    i want its complete description
    an any one help me ?????

  7. seetharaman

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

  8. hello!
    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

  9. hi!!!!
    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

  10. keshav bargaje

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

  11. seetharaman

    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

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

  13. 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…

  14. omongin ronald eric

    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


  16. 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.

  17. 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

  18. sanjay saikia

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

  19. vignesh.s

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

    • admin

      have you adjusted the potentiometer R2??