A 3/32 inch brass rod 1 3/4 inches long is threaded to fit a hole in the top of the armature. A sliding weight, W, may be clamped in any position on the rod by means of a thumb-screw. Raising or lowering the position of the weight decreases or increases the natural period of vibration of the interrupter. Screwing the hook, M, in or out so as to shorten or lengthen it, decreases or increases the ratio of the make to the break.
Fig. 38. Diagram of Connections for an Independent Interrupter.
Fig. 38 shows a diagram of the connections of the interrupter. The standard, the thumbscrew, B, and the spring, G, form part of the primary circuit of the induction coil. The standard, the thumbscrew, S, the spring, F, and the electromagnets are placed in series with a six-volt battery and connected to the circuit breaker on the aerial switch, so that when the switch is thrown in position for transmitting, the interrupter will be set in operation.
A condenser must be shunted across the larger contacts of the interrupter in order to hasten the demagnetization of the core of the induction coil and create a higher e.m.f. in the secondary. The condenser must be suited in size to the induction coil with which the interrupter is to be used and so the following table is appended to serve as a guide.
The condensers are built up of alternate sheets of tin foil and paraffined paper. Connections are made to the sheets by means of tin foil strips which project out alternately from opposite sides as in the illustration.
The paper should be about two inches larger each way so as to leave a one inch margin on all sides of the tin foil.
Fig. 39. Construction of a Paper Condenser.