411 REFERENCE · Wikibooks
Electronics Handbook/Devices/Oscillator/Active Oscillator/Variable Frequency Oscillator or VFO/Colpitt Oscillator
Reference material by Wikibooks contributors. This retains its source identity and is not 411 news reporting.
Configuration
500px
Oscillation frequency
The ideal frequency of oscillation for the circuits in Figures 1 and 2 are given by the equation:
where the series combination of C1 and C2 creates the effective capacitance of the LC tank.
Real circuits will oscillate at a slightly lower frequency due to junction capacitances of the transistor and possibly other stray capacitances.
Colpitts oscillator