The Electro Bug is capable of operating as a standard semi-automatic key for use in radio, but was designed specifically for use in wired commercial current-loop telegraph service.
The defining feature of the Electro Bug is the electromagnet inside the prominent black box. (Pole pieces can be seen on the front and rear of the box.) Its function is very much like that of a common electric bell. When making dits, a set of contacts turn the electromagnet on and off at regular intervals, alternately attracting and releasing the pendulum arm. The result is an endless stream of dits.
A rheostat allows for the adjustment of current through the electromagnet to compensate for the current flow in different wired systems, and also acts as a circuit closer.
The attached video, produced by Jim Wades, WB8SIW, explains the operation in detail.
It has been suggested that the T-shaped carry handle would allow the device to be turned on its side and used as a straight key. This, however, could position the finger piece high enough above the desk top to make operation uncomfortable for the user.
A stripped-down, purely mechanical version–the Electro Bug Junior–omitted the electromagnet assembly, and operates essentially as a standard mechanical bug to compete directly with Vibroplex.
