MW Transmitter

Circuit Diagram
mw_transmitter
Components Required
  1. Resistors
    1. R1 (68 kilo ohms , 1/2W)
    2. R2 (82 ohms , 1/2W)
  2. Transistors
    1. T1 (BF194)
  3. Capacitors
    1. C1 (0.22 mfd, 50V)
    2. C2 (0.005 mfd, 50V)
  4. Gang capacitor
    1. G1 (2x type)
  5. Ferrite rod
    1. FR1 (15 cm long, 8 mm diameter)
  6. Antenna
    1. At1 (Antenna coil of medium wave radio receiver )
  7. Miscellaneous
    1. Battery, Dry cell 6V
    2. LS ( Loudspeaker, 8 ohms, 6 cm diameter)
    3. S1 ( Slide switch, single pole)
    4. Radio receiver ( for testing)
    5. PCB or Breadboard
    6. Flexible Wire
    7. Soldering rod etc..
Principle and Working

This transmitter can be used as an inter-room radio telephone. The communication range of this transmitter is 5 meters only, but the range can be increased to 10-12 meters by installing a 2.5m long antenna horizontally at a height of about 3 meters.

The transmitter begins to work when S1 is switched on. The audio of this transmitter can be heard on a MW band domestic radio receiver placed at some distance. The audio can be heard any where between 1200 to 1600 kHz range. The frequency of the transmitter can be adjusted by gang capacitor to get clear reception, and to change the transmission frequency.