What is a trembler switch?

A trembler switch operates by vibrations. Vibrations cause the switch mechanism to complete or interrupt an electrical circuit. It can be used to trigger and alarm, turn on lights or many other devices. A simple trembler uses a metal can (soup can) with a small hole in the top and a weight suspended from a bare wire through the hole with a weight attached to the end of the wire (the hole must be large enough so the wire does not make contact with the can). The other end of the wire is connected to a battery (or other power source). The other pole of the battery is connected to the can. When vibrations cause the weight to move enough to cause the bare wire going through the hole in the top of the can to contact the can the circuit is completed.