| [1] | Magnetic permeability is the conducting power for lines of magnetic force. |
| [2] | See hysteresis under Magnetic Detector. |
CHAPTER V. INTERRUPTERS.
We now come to what is the greatest source of trouble and annoyance in an induction coil, namely the interrupter. Too much importance cannot be attached to this instrument, for upon it depends largely the satisfactory working of the coil. The operation of an induction coil and the part played by the interrupter were fully explained in the chapter on induction coils.
An adjustable interrupter is necessary for large coils, that is, one not only whose speed may be governed, but also the time and duration of the break.
Fig. 33. Simple Interrupter.
The rapidity of oscillation of a mechanical interrupter is a very different thing from the speed of break. The ideal speed of break is instantaneous. In wireless telegraphy, very faint signals are heard more distinctly in telephone receivers if the rate of interruption at the station sending them is high. The human ear is somewhat more sensitive to sounds higher than those ordinarily produced in the telephone receivers of a wireless receptor. This seems to argue the use of a high-speed interrupter to make and break the current. But the effect on the coil must also be considered.
In the first place, where a condenser is shunted across the terminals of the secondary as is the case with a wireless transmitter, a high-speed interrupter would be very likely to set up harmful oscillations in the secondary of the coil itself.
Second, if too fast, the rise and fall of the secondary currents will be caused to run into each other, since the break will occur before the primary current has reached a maximum and the reverse secondary current has died away.