Silent alarm (CB22471E)

This circuit is from a Popular Electronics from 1992. The circuit powers an LED when triggered.

Transistor Crystal Oscillator (CB5115E)
The resonant circuit depends on the crystal frequency that can go up to a few megahertz. The...
ICL7135 Plasma Display Circuit (CB15362E)
This circuit is from the 1983 Intersil Databook. The display is plasma and must be excited by a...
Common Emitter Stage (CB4936E)
This is a typical common emitter amplifier stage configuration. The transistor can be used...