INDOOR ALARM SIREN M21 Basic features M21 is an indoor acoustic alarm siren designed for anti-burglary and anti-fire alarm systems. The source of acoustic signal is a highly effective ‘quasi’ piezoelectric transducer. The external cover is made of ABS providing high resistance to shock and mechanical damages. The siren has an anti-sabotage protection against cover-intrusion and wall removal tamper. Installation The M21 siren should be mounted on a relatively flat surface, away from easy reach to minimize the risk of sabotage. For proper installation attach the siren to the surface with screws and strut studs (screws and strut studs come in set with the siren). Attention!!! The anti-sabotage protection will be operational only when the additional screw is mounted. See figure below. Tearing the device off chips a part of the base with a micro switch thus breaking the anti-sabotage circuit. Activation methods The M21 has two activation inputs: acoustic signal input (melody 1) marked #S1 and #L/S2 for the second melody. Applying power to either input will activate the respective signal. Anti-sabotage circuit connected to SAB terminals with the housing cover shut is normally closed (NC). Technical data: Sound pressure: 109 dB/m Nominal power: 13,8 VDC Max. power consumption: 0,14A Dimensions: 85 x 123 x 28 mm Working temperature: -35°C +60°C
Mounting hole
#L/S2 GND #S1 SAB SAB
Mounting holes