4093 Sine Square Converter (CB26335E)

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

Voltage indicator (CIR22153E)
This circuit indicates whether the voltage to be measured is higher or lower than the zener diode...
Dual indicator (CB22136E)
Obtained from an English publication, this circuit actually needs a current limiting resistor,...
Constant Current Source (CB13073E)
Constant current sources are used in applications such as battery chargers, electrolytic tanks, etc....