BELLS [Electric]

BELLS [Electric]

• A range of Electric Bells for use in school laboratories.

(Wikipedia excerpt: .."...An electric bell [B] is a mechanical or electronic [B] that functions by means of an electromagnet. When an electric current is applied, it produces a repetitive buzzing, clanging or ringing sound. Electromechanical [B] have been widely used at railroad crossings, in telephones, fire and burglar alarms, as school [B] , door [B] , and alarms in industrial areas, since the late 1800s, but they are now being widely replaced with electronic sounders. An electric [B] consists of one or more electromagnets, made of a coil of insulated wire around an iron bar, which attract an iron strip armature with a clapper..

Electric [B] are typically designed to operate on low voltages of from 5 to 24 V AC or DC. Before widespread distribution of electric power, [B] were necessarily powered by batteries, either wet-cell or dry-cell type.[2] [B] used in early telephone systems derived current by a magneto generator cranked by the subscriber. In residential applications, a small bell-ringing transformer is usually used to power the doorbell circuit. So that [B] circuits can be made with low-cost wiring methods, [B] signal circuits are limited in voltage and power rating.[3] [B] for industrial purposes may operate on other, higher, AC or DC voltages to match plant voltages or available standby battery systems.[4]....")

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