4093 Sine Square Converter (CB26335E)

Found in a Popular Electronics from the 90s, this circuit operates up to about 5 MHz input.

Optical Gain Control (CB6324E)
This simple circuit controls the signal amplitude through a photoresistor optical coupler. The...
Or exclusive with transistor (CB7249E)
In the figure we have the way to obtain the Exclusive-OR function with 1 transistor. The circuit...
Experimental Bicycle Speedometer (CB18710E)
This circuit uses as an indicator a common micrometer type VU with 200 uA of full-scale current. The...