Current to voltage converter (CB7332E)

This circuit is from a Popular Electronics from the 90s. The integrated circuit admits equivalents that must be tested.

Squarer Oscillator LM139 (CB4008E)
This traditional configuration that any Series 139 comparator can use is found in the 1990...
Piezoelectric Transducer Amplifier (CB13095E)
The circuit shown in the figure can be used to detect vibrations or to provide amplified acoustic...
Mini Organ (CB21653E)
This toy organ was found in Popular Electronics from January 1967. It can be constructed from...