This crystal oscillator generates a 20 MHz signal. Equivalent transistors such as BF494 and 2N2222 can be used. The stabilizing diodes can be 1N4148.
Found in a 1968 Mullard manual, this circuit can function as an infrared audio link. The...
This very low frequency oscillator was found in a Popular Electronics from the 90s. The circuit...
This very old circuit, from a publication from the 1970s, uses a germanium transistor and two...