Motorcycle headlight monitor (CB9117E)

This simple circuit was found in Popular Electronics from the 1980s. The circuit uses an LED as an indicator.

High Q Notch Filter (CB15639E)
This high Q “rejector” or notch filter rejects signals whose frequencies are in the range...
Basic two-gate oscillator (CB22399E)
This circuit was found in documentation from the 90's, having an LC compensation network. The...
Pulse Triggered Monostable (CB25672E)
This two-transistor circuit was found in the January 1994 issue of Electronics Now magazine....