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.
Found in the 1974 Ferranti transistor manual, this Schmitt trigger circuit uses general-purpose transistors...
This circuit was developed to test suspect 4001 and 4011 integrated circuits. The circuit is from...
This power source with silicon diodes at a time when valves were still used was found in Radio...