The device presented here is a model of the electromagnetic relay invented around 1850 by the Swiss watchmaker Mathäus Hipp (1813-1893), which took the place of those previously used in the entire Swiss telephone network and which allowed a reduction in the number of relays from 23 to 11.
The need to use an automatic repeater in telegraphy derived from the fact that when the electricity that carried a message arrived at the telegraph receiver at the end of a long line it was sometimes so weak that it would fail to make it work. In such cases, it was of little use to increase the power of the generator supplying the line. The discovery of the electromagnetic relay allowed Charles Wheatstone (1801-1875) in 1858 to solve this problem in a quite simple way by introducing a device that opened and closed an electrical circuit under the action of a weak current in arrival. This circuit, powered by a local generator, was capable of supplying a sufficiently intense current to allow the receiver to work (the typical function of a repeater relay).
An electromagnetic relay is essentially made up of an electromagnet whose mobile armature is fixed to one of the arms of a lever. When electricity circulates through the electromagnet, the armature is attracted by a circuit breaker which has contacts fixed at the extremity of the other arm of the lever and closes another circuit. ...continues