This two-transistor circuit consists of a powerful industrial-use siren. The circuit is from a Radio Electronics from November 1963. The powerful power supply is included.
Found in 1967 Raytheon documentation, this circuit uses a company coupler consisting of a lamp and...
In a modern version this circuit can use an LED in series with a resistor in place of the lamp. The...
This circuit, when triggered, locks, and remains so until the source is switched off for a moment or...