Thus, the nature of the secondary winding must be decided  according to the balance of those two factors deemed most  suitable for the work to be undertaken. The relation is not  really so simple as here stated, other factors complicating it;  but discussion of those is not essential to a working under-  standing of the coil. Beference to the previous discussion of  the most suitable current for exciting X-ray tubes (on p. 63)  will explain the interest and importance of this point.

2. Strength of the primary current is, of course, under  our direct control. Use of very heavy currents compels con-  sideration of special points concerning self-induction of the  primary winding, but those do not come within the purpose of  this section, since such currents are prohibited by the use of  a vibrating break.

With such a break it is said that a current of much more  than 20 volts cannot well be used, since the platinum contacts  will wear away too quickly and will have a tendency to stick,  thus endangering the primary winding.

We have had good results with a current of 24 volts, and,  with careful working, had little or no trouble; but probably  we were very near the margin of the safe limit.

No related posts.