Freeze Alarm (CB14454E)

The circuit of a 1968 publication can be implemented with more modern transistors such as BC548 for NPN and BC558 for PNP.

10 meter bamd receiver (CB23937E)
This 5-transistor receiver was obtained from an article in the February 1969 Radio Electronics magazine....
Computer Voice (CB9859E)
The oscillation of the relay causes the applied audio signal to deform and start to resemble the...
10W Amplifier (CB23878E)
Using period transistors, this 10 W amplifier was found in Radio Electronics magazine from May...