Electronic detector for smoke - has dual ionisation chamber with two independent alarm circuits and smoke simulator for testing

摘要

The smoke detector is electronic and is powered by a 24 V. battery, stabilised at 15 V. It uses the phenomenon of air ionisation due to a source of alpha rays, emitted from radio-active sources fitted to the upper inner metal surfaces of two ionisation chambers. A filter permits smoke to enter the lower chamber and the carbon particles capture free electrons. The current in this lower chamber is reduced, the voltage increases and the alarm activated. A test circuit is also incorporated, enabling the presence of smoke to be electronically simulated.