| 摘要 |
An alarm system to detect combustion products such as smoke, gas and the like, has one or more alarm signal sending units and an alarm signal receiving unit interconnected by wiring to the sending units. Each alarm signal sending unit has a sensing or response element to detect the presence of vapors or smoke and the like and provide a signal; the sending unit also includes an amplifier non-continuously brought to its current-carrying state for amplifying an output signal of the response elements responding to a change of the surrounding physical condition. The alarm signal sending units are suitable for being connected in large numbers in parallel with a common alarm signal receiver unit, because the amplifier in each sending unit has a high impedance and dissipates low power. A smoke-sensing element of the ion type and necessitating no repeater is expediently included in the alarm signal sending device.
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