Clack Clack Electronic Bell

Circuit Diagram
clack_clack_electronic_bell
Components Required
  1. Resistors
    1. R1 (100 ohms , 1/2W)
    2. R2 (470 ohms , 1/2W)
  2. Transistors
    1. T1 (AC126)
    2. T2 (LS100)
  3. Capacitors
    1. C1 (0.22 mfd, 50V)
    2. C2 (0.22 mfd, 50V)
  4. Preset
    1. Vr1 (2 mega ohms)
  5. Miscellaneous
    1. Battery 6V or Dry cell (6 x 1.5)
    2. LS ( Loudspeaker, 8 ohms, 6 cm diameter)
    3. S1 ( Slide switch, single pole)
    4. TR1 (Transformer)
    5. PCB or Breadboard
    6. Flexible Wire
    7. Soldering rod etc..
Principle and Working

This is a very simple electronic bell. Here the transistor TR-1 acts as a low frequency oscillator. Transistor TR1 also acts as a pre-amplifier. Oscillations generated from TR-1 is fed to the transistor TR2 which is a small audio amplifier. Preset Vr1 can be used to vary frequency, which will change the output tone of the bell.