42 kHz oscillator (CB21805E)

This circuit was used as an eraser for old tape recorders. The circuit is from a 1960 Mullard transistor manual.

Photo controlled triac (CB8312E)
This circuit was found in an Electronics World of 1968. It can be applied to any modern triac and...
Listening Monitor and 27 MHz Field Meter (CB19602E)
This circuit is from a documentation from the 70s. The transistors are types of germanium of the...
Audio Preamplifier (CB6479E)
Obtained from a 1996 documentation, this circuit uses common components and has a voltage gain of 200...