Franklin oscillator
The Franklin oscillator is an electronic oscillator circuit and was developed by Charles Samuel Franklin . This circuit is used to generate a frequency-stable sinusoidal oscillation .
functionality
The circuit consists of an oscillating circuit without a tap and a two-stage amplifier and in its original form consists of electron tubes in a basic cathode circuit . Transistor circuits customary today use the emitter circuit or source circuit. The coupling capacitances between the amplifier and the resonant circuit are smaller than with other oscillators. Therefore changes in temperature, supply voltage and load resistance have little influence on the generated frequency.
example
The parallel resonant circuit in the picture on the right is connected to the input of the two-stage triode amplifier via a coupling capacitor with 2 pF . The output of the amplifier is also connected to the resonant circuit with a 2 pF capacitor. The third tube, a tetrode , works as a buffer stage.