‘The bells, the bells!’ Spare a though for the fictional Quasimodo living up in the tower of Notre Dame, the noise of the bells driving him slowly mad and deaf.  Would it be the same if he had to listen to sirens?

Almost all alarms pre 1980 used bells, a 6” standard dome bell, both inside and outside. Now though sirens have replaced the humble bell as the weapon of choice for most installations. Bells being reserved for fire alarms. But if you think about it, the main purpose of a bell in a fire alarm is to get let the occupants know there is (possibly) a fire and to get them out asap!

If you have ever been anywhere near a standard 6” dome bell, going full tilt, it tends to get your attention pretty quick, you’re not going to hang around, especially when your teeth start to vibrate.

When you are designing your alarm system give some thought to making plenty of noise inside when the alarm activates. Nothing is more unsettling to a burglar than a major racket taken place. Consider using two internal sounders, maybe a bell and a siren or ever two sirens  or two bells, make lots of noise. Just make sure the control panel you are using has enough power to run them, if not consider a bigger panel or even a separate power supply, switched using a relay.

Making lots of noise will minimise the amount of time the burglar will spend on the premises, less time less things get stolen.

Check the section in the How to Guide on Electromagnetic Bells and Internal Sounders.