Practice code oscillator (CB21090E)

Found in Popular Electronics from the 90's, this circuit consists of an audio oscillator for Morse code practice.

Liquid level sensor (CB23807E)
This sensor was published in Radio Electronics magazine in April 1962. The two-transistor circuit...
DC Motor Control 555 (CB24908E)
Another of the many similar configurations we have in this section. This one is from a Radio...
Solenoid Current Monitor 2 (CB5400E)
This circuit like the previous one is intended for 24V x 3W solenoids being connected from the...