Circuit Diagram
Components Required
-
Resistor
- R1 (68K , 1/2W)
- R2 (82 ohms , 1/2W)
-
Transistor
- T1 (BF194)
-
Capacitor
- C1 (0.22 uf, 50V)
- C2 (0.005 uf, 50V)
-
Gang capacitor
- G1 (2x type)
-
Ferrite rod
- FR1 (15 cm long, 8 mm diameter)
-
Antenna
- At1 (Antenna coil of medium wave radio receiver )
-
Miscellaneous
- Battery, Dry cell 6V
- LS ( Loudspeaker, 8 ohms, 6 cm diameter)
- S1 ( Slide switch, single pole)
- Radio receiver ( for testing)
- PCB or Breadboard
- Flexible Wire
Principle and Working
This transmitter can be used as an inter-room radio telephone. The communication range of this transmitter is few meters only, but the range can be increased to by installing a 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 (Medium Wave) band domestic radio receiver placed at some distance. The audio can be heard anywhere 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.