Wednesday, 2 July 2014

27MHz TRANSMITTER with Crystal

Fig 1 shows a simple 27MHz transmitter producing a carrier.

(receiver for this circuit HERE)

The 27MHz transmitter PC board

Here is the circuit made by Lucian Papadopol
He has created capacitor values by paralleling two values.

This means it produces an unmodulated 27MHz signal and when picked up by a receiver, such as shown in fig 2, the result is a clean, noise-free reception. To increase the output of the transmitter, the 390R resistor is replaced by a 220R. This increases the current from 7mA to 12mA. The resistor could be decreased to 150R for more output.