JPS6242320B

An ionization smoke detector containing at least one ionization chamber operated at an extra low voltage or potential. The ionization chamber contains a sensor employing a measuring electrode and a counter electrode. Ambient air has practically free access to the ionization chamber and there are provided one or more radioactive sources for generating ions, a supply voltage source and an electrical circuit for triggering an alarm. The smoke detector possesses increased operational reliability since circuit elements are provided which enable signal reporting to a central station by means of a low-voltage of about 200 volts, however the sensor is operated at an extra low voltage.