Relative impedance meter (CB7487E)

Found in a 1960 Sylvania manual, this circuit can be implemented with a modern equivalent transistor like the BC558.

Photosensor for robot follows the line (CB26018E)
This simple robot or motor control circuit using a photocell as a sensor was found in the magazine...
Light Modulator 741 (CB16810E)
This circuit uses an operational amplifier to modulate the light emitted by an LED with audio...
Transistor Monostable (CB19361E)
Equivalent transistors, such as the BC548, can be used in this circuit that we find in...