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 circuit uses a photo-transistor to trigger a circuit sourcing a square signal for the output. The...
This circuit makes use of an uncommon integrated circuit. It can provide a power of 6 W when...
The circuit is from an 80's publication, but the components are current, only special type diodes...