RF or even switching transistors like the 2N2222 can be used in this circuit. The capacitors are ceramic and the frequency is determined by the crystal.
This simple circuit that senses energy cables (alternating current) through the field produced was found...
This interesting game was found in a 1987 publication, but it is very simple and can be easily...
This circuit was found in a 2006 documentation. Its purpose is to control a servo system in which...