### Reference Circuit

The following Colpitts Oscillator is built around a 2N3904 transistor. I verified its operation for various frequencies from 250 kHz to 1.5 MHz. The inductor is 20 turns of insulated 22 AWG wire on a 1.5 inch diameter cardboard core (the turns are as closely wound as practical, taking about 1.0 inches axially along the core). I measure the inductance as approximately . Capacitor values for the LC tank (lower left of schematic) are presented in a table.

Capacitor Value | Observed Frequency |
---|---|

The oscillator gave best performance at capacitor values 33 nF and 22 nF.