The first circuit is shown in figure 3 and uses a 2N2222 transistor or equivalent. This circuit can operate at frequencies in the 500 kHz range up to a few tens of Megahertz. It is a Colpitts oscillator in which the feedback is made by capacitive derivation, with the signal taken from the emitter of the transistor and reapplied to the base. The circuit is powered with a voltage of 12V and the output power is in the order of a few milliwatts. In this circuit, the crystal operates at its fundamental frequency.
