‘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 it seems sirens have replaced the humble bell as the weapon of choice for most installations.

Most people commonly think of motion detector lights as excellent additional security for your house. However there are many instances where the can also be used indoors. These light sources can be very cost effective and can be energy efficient. There is also the 'cool' factor of walking into a room, garage, basement, etc and the lights simply come on and then switch off once you leave. How cool is that!

Generally speaking, alarm bells used for intruder alarm systems have a dome size of between six and nine inches, the bigger the louder. As will most other devices in alarm systems they work on 12vDC and draw about 180mA. Again the bigger the bell the more current it will draw. Check when installing to ensure you have a big enough back up battery. (see section on power supplies and batteries).