Optical sensor for PC (CB20548E)

This circuit was found in a PC documentation from 1996. It can be used as a shield with modern microcontrollers.

Capacitance multiplier (CB7803E)
We found this circuit in an old Popular Electronics. The circuit can be applied to other...
27 MHz Converter (CB16876E)
With this circuit it is possible to receive the signals from the 11-meter band (27 MHz) in a...
60 V Bidirectional Motor Control (CB19568E)
We found this circuit in an American publication from the 90s. The transistors must be provided with...