To operate in a harmonic of the crystal frequency, tuned to a trimmer in the resonant circuit of the transistor collector, we have the circuit of the figure. The transistor used is the 2N2222 or equivalent that can oscillate at the desired frequency. The supply of this circuit is also made with a voltage of 12V. We warn that in these high frequency oscillating circuits, preference should be given to the use of ceramic capacitors and even mica in the most critical functions.
