This circuit was found in an Electronic Experimenter Handbook from the 90's. The coil can be formed by 4 turns of wire 28 with 0.5 cm diameter without core for the FM band.
This circuit was found in an Electronics World of 1968. It can be applied to any modern triac and...
This circuit is from a documentation from the 70s. The transistors are types of germanium of the...
Obtained from a 1996 documentation, this circuit uses common components and has a voltage gain of 200...