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They are all in circuit one with another, and a wire connects the ends of each coil to corresponding metal bars on the commutator C. These bars are insulated from each other on the spindle X of the armature. Now, as each coil passes through the magnetic field in turn, a current is excited in it. Each coil therefore resembles an individual cell of a voltaic battery, connected in series.
The deflective repulsion exhibited by B will, when its circuit is completed by the commutator and brushes, as described, act to place its plane at right angles to that of C; but being then open-circuited, its momentum carries it to the position just past parallelism, at which moment it is again short-circuited, and so on. It is capable of very rapid rotation, but its energy is small.
It occurred to me, however, that the rapid alternations of the exciting current from the dynamo, and the consequent speed of magnetic molecular rotation, gave the latter a certain momentum, and that by widening the insulating strips of the first or main current commutator, and proportionately increasing the width of conducting surface in the shunt commutator up to certain limits, this effect would be increased.
It consists of a single armature core with a motor winding and a generator winding on it and each of these has its own commutator. Where the low voltage current flows into one of the windings it drives its as a motor and this in turn generates the higher voltage current in the other winding. Get a 100 watt 350 volt motor-generator; it is shown at F and costs about $75.00. The Panel Cut-Out.
In the "shunt-wound" machine the field magnets are excited by diverting a small portion of the main current from the armature through them, by means of a "shunt" or loop circuit. Thus in figure 42 where C is the commutator and b b' the brushes, M is a shunt circuit through the magnets, and E is the external or working circuit of the machine.
This current is purely a secondary effect, of short duration, and only occurs once at each break of the commutator. The motor is of such a size that when supplied with a continuous current of proper strength the induced electrical effect in the shunt circuit will light one incandescent lamp.
I chased a whole row of things one after another battery, buzzer, oil or gasoline in the cylinders, defective insulation, commutator, water in the carburettor, choked feed-pipe, and all it did was to cough in a dreary, tow-me-home-to-mother sort of way, "If the captain had known anything about engines and could have made it start, I expect I would have married him and lived happy ever afterward.
Those who have facilities for carrying out experiments may prove it in the following manner: E, in the inclosed drawing, is an electro-magnet whose brushes press on two metallic bands, B and B, fixed to but insulated from the spindle, A. The band, B, is in electrical circuit with the shunt commutator, S, and the main commutator, M; while the band, B, is in contact with shunt commutator, S, and main commutator, M. This contact is made by conducting rods, as indicated.
The insulating strips in the commutator are sufficiently wide to demagnetize the whole of the machine before reversibility in the armature takes place, and this demagnetization sets up a direct induced current, which is caught in a shunt circuit by the aid of a second commutator, which only comes into action when the first commutator goes out.
The electromotor was invented by Professor Jacobi; it virtually consisted of two disks, one of which was stationary, and carried a number of electromagnets, while the other disk was provided with pieces of iron serving as armatures to the pole pieces of the electromagnets, which were attracted while the electric current was alternately conveyed through the bobbins by means of a commutator, producing continuous rotation.
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