Electronics Handbook/Devices/Oscillator/Active Oscillator/Variable Frequency Oscillator or VFO/Clapp Oscillator

Configuration

 * Clapp_oscillator.png

Oscillation Frequency
$$ f_0 = {1 \over 2\pi} \sqrt{ {1 \over L}             \left(   {1 \over C_0}                     + {1 \over C_1}                     + {1 \over C_2}              \right)} \. $$