Transistor - direct current - change in current converter which, with a wellenfoermigen switching current is controlled, and in connection with a change in current amplifier for detecting and measuring of small gleichstroeme serves

摘要

1,046,447. Transistor switching and amplifying circuits. SOUTHERN INSTRUMENTS Ltd. May 2, 1963 [June 4, 1962], No. 21535/62. Heading H3T. A D.C. to A.C. signal converter for the measurement of D.C. currents comprises a pair of semi-conductor switching devices T4, T6 arranged to be both switched on and off simultaneously, each device being supplied with an input D.C. signal, their outputs being combined in such a way that residues produced in the switching process are substantially cancelled and an output signal is produced dependent on the difference between the two D.C. signals. A further pair of transistors T3, T5 may be employed, arranged so that T4 and T6 are switched on before T3 and T5 are switched off. The circuit is balanced so that residues due to capacitance and carrier storage and the ringing transients set up in transformer TR1 are minimized. The invention may be applied to a differential polarograph in which current differences between two cell circuits of the order of 10SP-10/SP amps. may be detected in the presence of standing currents several orders larger. Reference has been directed by the Comptroller to Specification 990,685.