Detection of products of combustion

Claim 2

In a warning device having a power source, means for detecting a predetermined condition and thereupon emitting a signal, an amplifier having a power input connected to said source and a signal input connected to said detecting means for amplifying the signal, a trigger device connected to the amplifier to be triggered upon reception of the predetermined amplified signal, and an alarm unit connected to said trigger device to be energized when the latter is triggered, the improvement comprising, in combination with rate of change detecting means, a plurality of capacitor banks adapted to be connected selectively to the amplifier power input, and switch means for selectively adding said capacitor banks to the amplifier power input to vary the time constants and thus the detecting sensitivity of the device.

Claim 3

In a device as set forth in claim 3, said switch means comprising a plural position switch including a plurality of positions for selectively adding capacitor banks to the amplifier input and a further position for bypassing said trigger device and directly connecting said Alarm unit to the power source, said switch means in its said further position in the absence of an alarm serving to test the operability of the alarm, and following an alarm serving to trip said trigger device and thereby reset the same.

Claim 4

In a device as set forth in claim 4, wherein the device includes a load unit connected to the primary source; a supervisory circuit comprising a secondary power source, a capacitor in series with said secondary source, means coupling said capacitor to one side and said secondary source to the other side of said load unit to sense the voltage drop thereacross, second trigger means responsive upon charging of said capacitor for connecting said alarm unit in series with said secondary source, said capacitor being charged by said secondary source when the voltage drop across said load unit falls below a predetermined value and when charged triggering said second trigger means, said second trigger means during discharge of said capacitor causing said secondary source to energize said alarm unit, whereby the alarm unit emits periodic alarms of short duration when the output of the primary source falls below a predetermined value.