ABSTRACT
The sirens can also be used as alerts or alarms. Their sound level is between 100 dB and 110 dB. For maximum loudness, the siren must be firmly attached to the enclosure or circuit board.
A sounder is a brass disc coated with piezoelectric material. It may be driven directly by a 3 V peak-to-peak square wave generated by CMOS logic. It is useful for producing a variety of ‘alert’ sounds. Sounders are made in different diameters with different resonant frequencies. For maximum effect, the sounder should be mounted firmly on the enclosure or circuit board and be driven by a signal close to its resonant frequency.
