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.

Sequential LED (CB7860E)
The UAA170 integrated circuit is not very common today. This project is for a 303 Circuits from the...
Crystal oscillator (CB23647E)
This circuit of various uses on the bench was found in Radio Electronics magazine from January 1960....
Alternating Voltage Regulator (CB1581E )
National Semiconductor suggests the figure circuit for stabilizing the peak value of an...