Smoke-detector

  
This circuit comes from U.S. Patent 3, 778,800, granted to BRK Electronics in Aurora, IL. The circuit provides a smoke detector with an alarm for both smoke and low batteries. The R6/R7 voltage divider monitors the battery and will turn Q2 and Ql off when the battery voltage falls too low. The smoke-detector chamber will also cut Ql off when it senses smoke.
Smoke-detector - schematic

Ql via Q3, triggers SCR Dl and sounds the alarm. Capacitor Cl provides feedback that causes the alarm to sound intermittently. The smoke detector and low-battery circuits sound the alarm at two different rates.




Leave Comment

characters left:

New Circuits

.