This circuit uses a parallel resonant crystal to control the frequency. The circuit is from Radio Electronics magazine, February 1993. Equivalent transistors can be used.
Indicated for discriminators adjustment in FM and VHF receivers, this circuit was found in a 90s...
This circuit doubles and reverses the polarity of voltage Ve which can be between 5 and 15 V. The...
We found this circuit in a 1968 Electronics World. The circuit uses a transistor of the time...