The circuit is from 80s Siliconix documentation. The integrated circuit is from the company and is not common today. It can be used operational equivalent more common in our times.
Found in a Popular Electronics from the 80's, this circuit triggers an SCR keeping an LED on when...
This circuit was found in a 1994 documentation. Speed measurement pulses are obtained by a reed...
I found this Vox circuit or acoustic receiver as it was originally called, in a 1973 publication. The...