Linear Amplitude Modulator (CB21087E)

Found in an Analog Devices documentation from the 90s, this circuit uses a component of the time, not common nowadays.

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...