Alarm connectable to an external AC power supply for standby power and comprising battery

摘要

An alarm for detecting radiation and/or pollutants such as smoke, carbon monoxide or the like, the alarm comprises: an alarm circuit (12) including detection means (14) for detecting the radiation and/or pollutants, and an audible alarm (16); a power supply circuit (24) connectable to an external AC power supply for supplying standby power to the alarm circuit (12); and a battery (20) for supplying power to the audible alarm (16) when the alarm is energised. The power supply circuit (20) is configured to supply current to the alarm circuit (12) at a level less than that required to energise the audible alarm (16).