figure, are designated by the letters E, F.
The primaries H, H' of the induction coils or transformers are connected either in parallel or series with a source of direct or continuous current I, and the number of convolutions is so calculated for the strength of the current from I, that the coils J, J' will be saturated.
The connections are such that the conditions in the two transformers are of opposite character, that is to say, the arrangement is such that a current wave or impulse corresponding in direction with that of the direct current in one primary as H, is of opposite direction to that in the other primary, H', hence it results that while one secondary offers a resistance or opposition to the passage through it of a wave of one sign, the other secondary similarly opposes a wave of opposite sign. In consequence, the waves of one sign will, to a greater or less extent, pass by the way of one branch, while those of opposite sign in like manner pass over the other branch.
In lieu of saturating the primaries by a source of continuous current, they may be included in the branches C, D, respectively, and their secondaries periodically short-circuited by any suitable mechanical devices, such as an ordinary revolving commutator.
