Electricity: electrical systems and devices – Control circuits for electromagnetic devices – Systems for magnetizing – demagnetizing – or controlling the...
Patent
1982-11-16
1984-07-24
Goldberg, E. A.
Electricity: electrical systems and devices
Control circuits for electromagnetic devices
Systems for magnetizing, demagnetizing, or controlling the...
361178, 7386112, 7386117, G01F 158
Patent
active
044620608
ABSTRACT:
A driver for the excitation coil in the electromagnet of an electromagnetic flowmeter, wherein the fluid to be metered is conducted through a flow tube to intersect the transverse magnetic flux field created by the electromagnet. The driver includes an a-c line rectifier whose output is coupled to the coil by a pair of switching transistors, the control electrodes of which are connected to the output of a comparator having first and second input terminals. Applied to the first terminal of the comparator is an alternating square wave voltage, each cycle of which has a positive and a negative gating pulse such that the transistors are alternately actuated, the arrangement being such that the rectified output is applied by the transistors to the coil with a polarity which is alternately reversed. The comparator includes a positive feedback loop connected between its output and the first terminal to produce a pulsatory output so that during each negative and positive gating interval, the coil is excited by a train of pulses whose duty cycle is varied in a manner regulating current flow through the coil to maintain a substantially constant current level.
REFERENCES:
patent: 3783687 (1974-01-01), Mannherz et al.
patent: 4144751 (1979-03-01), Yokoyama
patent: 4204240 (1980-05-01), Schmoock
patent: 4325261 (1982-04-01), Freund, Jr. et al.
patent: 4339958 (1982-07-01), Shauger
patent: 4370892 (1983-02-01), Schmoock
Ebert Michael
Fischer & Porter Company
Goldberg E. A.
Jennings Derek S.
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