UM66 Musical door bell alarm circuit- Melody generator

This circuit is suitable for musical bell in doors, home security alarm systems,  burglar alarms etc. The main part of this alarm circuit is an UM66, which is a melody generator IC.  It is a very small IC that almost looks like a transistor, it has an inbuilt tone and a beat generator. This IC is programmed to generate certain frequencies.When power is turned on, the melody generator is reset and melody begins from the first note.
Many versions of UM66T are available which generate tones of different songs. The power (Vcc) for this circuit should not exceed 3V or else it may lead to the damage of our UM66 IC. If you want to join this circuit to other circuits, sharing a common Vcc which is greater than 3V then a zener diode voltage regulator can be employed. This is a very simple battery powered melody generator circuit. Feel free to leave a comment in the comment box below for any doubts. 

Circuit Diagram

Components Requiered

  1. UM66 Musical IC
  2. Resistor 100Ω
  3. Transistor BC547
  4. Speaker
  5. 3V Battery

Working

  • When power is switched On, UM66 starts to generate the melody current.
  • The output from the UM66 IC has no sufficient power in order to drive a speaker. So we are using an NPN transistor as an amplifier.
  • The operating voltage of UM66 is 1.5V to 3V. The supply voltage should not exceed 3V, If is happens, the IC will damage.

Components Pin out

i-St@r Lab

Here is the assembled form of above circuit in i-St@r Lab. The Zener diode is used for protecting UM66 from high voltage

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