. Dental and oral radiography : a textbook for students and practitioners of dentistry . its principles are the same (Fig. 15). In a way it isa double induction coil with the secondary of one coilacting as the primary of the other coil. An alternatingcurrent is utilized in the primary of the first coil and bymeans of the secondary of this same coil is stepped upto a high voltage. This stepped-up current is thencarried to a condenser. As the current leaves the con-denser, it is oscillating at a great rate of frequency andpasses into the primary of the Tesla, or second, coilwhere it induces a cu
. Dental and oral radiography : a textbook for students and practitioners of dentistry . its principles are the same (Fig. 15). In a way it isa double induction coil with the secondary of one coilacting as the primary of the other coil. An alternatingcurrent is utilized in the primary of the first coil and bymeans of the secondary of this same coil is stepped upto a high voltage. This stepped-up current is thencarried to a condenser. As the current leaves the con-denser, it is oscillating at a great rate of frequency andpasses into the primary of the Tesla, or second, coilwhere it induces a current in the secondary of this the terminals of the last secondary, it is carried tothe x-ray tube. The principles involved in this type ofapparatus are shown in Fig. 15. Like the current of the induction coil, the current fromthe Tesla coil is high in voltage and low in amperage, butunlike the current from the induction coil it is not uni-directional, but is alternating in character. For this rea-son, it is considered by some as being less desirable for X-RAY MACHINES .r)3. -o- -o- VVWV AAA <Uj VW\M/WWWW AAAAAAAM Fig. 15.—Diagram of the high frequency coil. T, alternating current transformer:C, condenser; G, spark gap; R, oscillation transformer; D, high tension discharge gap;X, high frequency 5c-ray tube. 54 DENTAL AND ORAL RADIOGRAPHY radiographic purposes. However, this apparently ob-jectionable feature is overcome by using an x-ray tubeconstructed in such a way as to cut out one wave of thecurrent and thereby produce practically the same resultas where a unidirectional current is used. These coils have the advantage of being less cumber-some, require less space and are less expensive than theother form of apparatus, but they cannot be dependedupon to do the character of work that the powerful in-duction coil or interrupterless transformer will this fact, this type of apparatus un-doubtedly has a place in the x-ray laboratory of the den-tis
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