Loublet Schematic

The danger always exists, when the fuel gases such as propane or gas are confined to a small area. The alarm of toxic gases figs. 1-45 utilizes a tin-oxide-semiconductor. A coil of thin wire heated by a battery 12 V via IC1 and IC2, which pulses the voltage to the coil of the sensor, saving a significant amount of energy. Diode Zener Dl provides a constant voltage to the filament coil sensor. resistance of the sensor reduces the sensor is exposed to toxic gases such as hydrogen, carbon

Carbon monoxide and propane. To reduce the resistance of the sensor, the SCR gate voltage increases. When the gate threshold voltage is reached, the SCR fires and a buzzer alarm is activated. Once activated, the bell and the switch S1 should be used to reset the alarm. Since the sensor has a good deal of thermal inertia, S1 must be off or open for about three or four minutes after the initial activation, allowing the sensor to stabilize, thus avoiding false alarms. R7 sensitivity control set to the desired value, before the activation of SCR.