Chopper-Operated Electromagnetic Flowmeter

Author

Abel, Francis L.

Author_Institution

Dept. of Physiology, University of Wisconsin Medical School, Madison, Wis.; Postdoctoral fellow, Wisconsin Heart Assoc., 1958-1959.

Issue

4

fYear

1959

Firstpage

216

Lastpage

219

Abstract

The problem of design of a square-wave electromagnetic flowmeter may be simplified by the use of a mechanical chopper as the gating device. Such an instrument has been assembled using commercial components costing less than $1000. A commercial 400-cycle chopper amplifier, Offner model 190, was modified to perform the sampling. Carrier signal was provided by Tektronix 162 and 161 generators. Proper synchronization with the chopper is obtained by use of the 161 delay control. Magnet assemblies were made of ferrite toroidal cores and platinum electrodes, cast in epoxy resin and powered directly by a Heathkit 70-watt amplifier. Using a carrier frequency of 400 cps, good frequency response, stability, and signal-to-noise levels were attained. Calibration curves are linear for forward and backward flow. Sensitivity was sufficient to record blood flow levels of 1 ml per minute.

Keywords

Assembly; Choppers; Costing; Delay; Electromagnetic devices; Frequency synchronization; Instruments; Sampling methods; Signal generators; Toroidal magnetic fields;

fLanguage

English

Journal_Title

Medical Electronics, IRE Transactions on

Publisher

ieee

ISSN

0097-1049

Type

jour

DOI

10.1109/IRET-ME.1959.5007969

Filename

5007969