The drop or relay controls a local circuit composed of an open-circuit battery and an ordinary vibrating bell.
Some forms of wet battery work in the same way as the dry battery, and are used like-wise for open-circuit work.
The chemicals that are used are usually different from those used in the open-circuit batteries and are much stronger.
The open-circuit battery is made in many different ways, so we only describe two of the principal ones.
It can be used, therefore, only in "open-circuit" work—such as door-bell circuits, and some forms of fire and burglar alarm.
A dry cell, Leclanché, or other open-circuit cell would not be at all suitable for a telegraph line, as it would soon polarize.
Then we reason that there is an open-circuit between F and G.
A dry battery will do, but if you use the sounder much, an open-circuit battery will soon use itself up.
|open circuit |
An electric circuit in which the normal path of current has been interrupted, either by the disconnection of one part of its conducting pathway from another, or by the intervention of an electric component, such as a transistor. Compare closed circuit.