This is a very common circuit in the days of xenon flashes for cameras. This is from a Radio Electronics magazine from November 1965. It uses an SCR and has manual triggering.
This circuit is originally recommended as hearing aid or stethoscope. The output transducer is a...
Originally suggested by Popular Electronics to control Christmas lights, this circuit can...
The purpose of this circuit is to detect output signals from a transmitter for the frequency range...