. Radiography and radio-therapeutics . without at the same time producingany inverse radiation. The principle of such an apparatus isas folloM^s : Alternating current is steppedup by means of a high-tension transformerto the pressure necessary to stimulate anX-ray tube, but as continuous current is essential, the high-tension alter-nating current is converted into a pulsating continuous current by meansof a synchronous rectifier. The chief factor is therefore a high-tension rectifier which is designedon the principle of the well-known commutator employed for dynamos andmotors. This rectifier i
. Radiography and radio-therapeutics . without at the same time producingany inverse radiation. The principle of such an apparatus isas folloM^s : Alternating current is steppedup by means of a high-tension transformerto the pressure necessary to stimulate anX-ray tube, but as continuous current is essential, the high-tension alter-nating current is converted into a pulsating continuous current by meansof a synchronous rectifier. The chief factor is therefore a high-tension rectifier which is designedon the principle of the well-known commutator employed for dynamos andmotors. This rectifier is coupled mechanically and electrically with themotor, alternating in such a manner that commutation takes place insynchronism with the frequency of the alternating current. For instance,if alternating current is available having a frequency of 50 cycles per second,the rectifier will give, in the same time, one hundred continuous currentimpulses, or expressed scientificallv, the rectifier is in synchronism withthe alternating Fi(i. 2.—Outtit tor alternating or con-tinuous current. For alternatingsupply there is a difference in tliearrangement of the interrupter.(Medical Supplj- Association.) ACCUMULATORS 13 The commutation of the rectifier always occurs at the moment whenthe alternating current is at zero value, that is, at the moment of the changeof direction. When working accurately this arrangement practically pre-vents the generation of inverse current which is so harmful to the tubes. Synchronism is obtained simply and absolutely by employing a rotaryconverter which is connected to a continuous supply, and which at the sametime supplies the alternating current to the transformer and rotates therectifier which is mounted on the same shaft. Alternating- Current Hig-h-tension Rectifier.—When using thealternating current, the current for the transformer is derived direct fromthe supply, the rectifier being driven by a self-starting single-phase synchron-ous motor
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