Current regulating circuit for diagnostic x=ray generator - using transistor threshold switch for on=off switching of heating transformer

摘要

The circuit controls the current for the X-ray tube in accordance with the threshold setting of a switch. This receives a signal corresponding to the instantaneous value of the effective heating current and its output controls the ON-OFF switching of the heating transformer (5). The signal representing the effective heating current is supplied by a series circuit with a squaring device (11) providing the square of the voltage across a measuring resistor (10) in the heating circuit (6...10) and an integrator (13) which is reset every half cycle. The measuring resistor (10) is connected across the DC diagonal of a rectifier bridge (9), with the AC diagonal lying in series with the heating circuit (6...10). The squaring device (11) pref. comprises a difference amplifier, while the threshold switch comprises a switching transistor (7) connected via a diode bridge (8) to the primary (6) of the heating transformer (5).