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    Electronic Hysteresigraphs

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    Four instruments are described: (1) A Miller integrator using an operational amplifier with specially developed low drift circuitry and means to convert maxwell-turns to gauss by directly inserting equivalent sample area-turns in panel control. The integrating band-width is from direct current to 100 kHz. Full-scale range is essentially 1 to 106 kilomaxwell turns with 1 V output. A modification with an additional Hall probe channel is also mentioned. (2) A complete hysteresigraph with X-Y recorder and yoke permeameter for blocks of hard magnetic material. Preset calibrations are provided to check accuracy through recorder and to match special papers developed for ferrite and for alnico materials. Second quadrant plus compressed first quadrant plotting with means for correctly locating B-H curve on the recorder paper, plus comments on pole coil measuring technique are included. Another paper contains additional information on the meaning of pole coil measurements. (3) A complete hysteresigraph for soft material in toroids, solenoids, or other permeameters. This has d-c curve plotting capability with built in X-Y recorder, and output for an oscilloscope when alternating current is involved. Power supply produces up to 10 amps d-c to 10 kHz, sine, triangular and square wave with autostart for plotting initial magnetization. Computer elements enable insertion of magnetic length and turns on power winding to give oersteds directly for toroids without further calculation. Maxwell turns are similarly converted directly to gauss as in the integrator. (4) A universal magnetic testing instrument consisting of a combination of the hard and soft hysteresigraph mentioned previously without duplication of sections that can be used in common. Soft material section has power supply and instrumentation that is adaptable to many traditional types of permeameters such as Epstein, Fahy Simplex, Medium H, Burroughs, etc., when impedance is reasonable match. When H is sensed through flux change in coil in the permeameter, or with a Chattock potentiometer, an additional integrator is needed otherwise no additional equipment is needed except for oscilloscope when it is desired to display a-c loops.


    hysteresis, magnetic materials, galvanometers, integrators, vibration, amplification, magnetization, magnetic measurement, measuring instruments, flux (rate), electronic test equipment

    Author Information:

    Fredrik, AH
    president, Magnos, Inc., Harvard, Mass.

    Committee/Subcommittee: A06.01

    DOI: 10.1520/STP36853S