Combustible gas detector

Claim 1

AN APPARATUS FOR THE DETECTION AND MEASUREMENT OF CONCENTRATION OF A COMBUSTIBLE GAS IN THE ATMOSPHERE WHICH COMPRISES A WHEATSTONE BRIDGE COMPRISED OF A PAIR OF SIMILAR PLATINUM FILAMENTS CONNECTED AS TWO ADJACENT LEGS THEREOF AND A PAIR OF RESISTORS CONNECTED AS THE OTHER TWO ADJACENT LEGS THEREOF, ONE OF SAID RESISTORS BEING ADJUSTABLE FOR BALANCING SAID BRIDGE, ONE OF SAID PLATINUM FILAMENTS BEING COMPLETELY ENCLOSED FROM THE ATMOSPHERE AND THE OTHER OF SAID FILAMENTS BEING EXPOSED TO THE ATMOSPHERE, MEANS FOR CONTINUOUSLY DRAWING SAMPLES OF THE ATMOSPHERE OVER SAID EXPOSED FILAMENT, MEANS FOR APPLYING AN ALTERNATING CURRENT BETWEEN THOSE ENDS OF SAID FILAMENTS WHICH ARE NOT ADJACENTLY CONNECTED TOGETHER FOR HEATING SAID FILAMENTS AND ENERGIZING SAID BRIDGE, AMPLIFIER MEANS FOR AMPLIFYING THE ALTERNATING CURRENT SIGNAL PRODUCED BY UNBALANCE OF SAID BRIDGE, MEANS FOR CAUSING SAID AMPLIFIER ALTERNATING CURRENT SIGNAL TO ACTUATE A GAS ALARM WHEN IT HAS REACHED A PREDETERMINED VALUE, AND DISABLING MEANS FOR PREVENTING AN ABNORMALLY HIGH SIGNAL CURRENT PRODUCED BY BRIDGE UNBALANCE RESULTING FROM A BURNED OUT FILAMENT FROM ACTUATING SAID GAS ALARM WHICH COMPRISES A PAIR OF DIODES CONNECTED BETWEEN THE INPUT OF SAID AMPLIFIER AND THE CONTROL ELECTRODE OF AN ELECTRONIC AMPLIFYING MEANS CONTAINED WITHIN SAID AMPLIFIER, THE CONDUCTION THRESHOLD OF EACH OF SAID DIODES BEING GREATER THAN THE UNBALANCE SIGNAL VOLTAGE RESULTING FROM BRIDGE UNBALANCE CAUSED BY A HIGH GAS CONCENTRATION AND LOWER THAN THE UNBALANCE SIGNAL VOLTAGE CAUSED BY A BURNED OUT FILAMENT, WHEREBY SAID DIODES PREVENT A NORMAL UNBALANCE SIGNAL VOLTAGE FROM DISABLING SAID AMPLIFIER, AND WHEREBY AN ABNORMALLY HIGH SIGNAL VOLTAGE RESULTING FROM A BURNED OUT FILAMENT CAUSES SAID DIODES TO BECOME CONDUCTIVE AND TO PERMIT A DISABLING VOLTAGE TO BE APPLIED TO THE CONTROL ELECTRODE OF SAID ELECTRONIC AMPLIFYING MEANS, PREVENTING THE ACTUATION OF SAID GAS ALARM.

Claim 2

AN APPARATUS FOR THE DETECTION AND MEASUREMENT OF CONCENTRATION OF A COMBUSTIBLE GAS IN THE ATMOSPHERE WHICH COMPRISES A WHEATSTONE BRIDGE COMPRISED OF A PAIR OF SIMILAR PLATINUM FILAMENTS CONNECTED AS TWO ADJACENT LEGS THEREOF AND A PAIR OF RESISTORS CONNECTED AS THE OTHER TWO ADJACENT LEGS THEREOF, ONE OF SAID RESISTORS BEING ADJUSTABLE FOR BALANCING SAID BRIDGE, ONE OF SAID PLATINUM FILAMENTS BEING COMPLETELY ENCLOSED FROM THE ATMOSPHERE AND THE OTHER OF SAID FILAMENTS BEING EXPOSED TO THE ATMOSPHERE, MEANS FOR CONTINUOUSLY DRAWING SAMPLES OF THE ATMOSPHERE OVER SAID EXPOSED FILAMENT, MEANS FOR APPLYING AN ALTERNATING CURRENT BETWEEN THOSE ENDS OF SAID FILAMENTS WHICH ARE NOT ADJACENTLY CONNECTED TOGETHER FOR HEATING SAID FILAMENTS AND ENERGIZING SAID BRIDGE, AMPLIFIER MEANS FOR AMPLIFYING THE ALTERNATING CURRENT SIGNAL PRODUCED BY UNBALANCE OF SAID BRIDGE, MEANS FOR CAUSING SAID AMPLIFIER ALTERNATING CURRENT SIGNAL TO ACTUATE A GAS ALARM WHEN IT HAS REACHED A PREDETERMINED VALUE, AND DISABLING MEANS FOR PREVENTING AN ABNORMALLY HIGH SIGNAL CURRENT PRODUCED BY BRIDGE UNBALANCE RESULTING FROM A BURNED OUT FILAMENT FROM ACTUATING SAID GAS ALARM WHICH COMPRISES A PAIR OF DIODES CONNECTED BETWEEN THE INPUT OF SAID AMPLIFIER AND THE CONTROL ELECTRODE OF AN ELECTRONIC AMPLIFYING MEANS CONTAINED WITHIN SAID AMPLIFIER, THE CONDUCTION THRESHOLD OF EACH OF SAID DIODES BEING GREATER THAN THE UNBALANCE SIGNAL VOLTAGE RESULTING FROM BRIDGE UNBALANCE CAUSED BY A HIGH GAS CONCENTRATION AND LOWER THAN THE UNBALANCE SIGNAL VOLTAGE CAUSED BY A BURNED OUT FILAMENT, WHEREBY SAID DIODES PREVENT A NORMAL UNBALANCE SIGNAL VOLTAGE FROM DISABLING SAID AMPLIFIER, AND WHEREBY AN ABNORMALLY HIGH SIGNAL VOLTAGE RESULTING FROM A BURNED OUT FILAMENT CAUSES SAID DIODES TO BECOME CONDUCTIVE AND TO PERMIT A DISABLING VOLTAGE TO BE APPLIED TO THE CONTROL ELECTRODE OF SAID ELECTRONIC AMPLIFYING MEANS, PREVENTING THE ACTUATION OF SAID GAS ALARM.