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Hall Switch Threshold Meter

IP.com Disclosure Number: IPCOM000045178D
Original Publication Date: 1983-Feb-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Holloway, JF: AUTHOR [+2]

Abstract

It is desirable to have a measuring instrument which will simultaneously read the positive switching threshold and negative switching threshold and the hysteresis of a magnetically actuated switch, such as a Hall switch, which may be used as a commutation signal generator in a brushless DC motor. The two threshold voltages and hysteresis will be displayed on three digital voltmeters, The scale factors can be selected so that the voltmeters can be read directly in gauss.

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Hall Switch Threshold Meter

It is desirable to have a measuring instrument which will simultaneously read the positive switching threshold and negative switching threshold and the hysteresis of a magnetically actuated switch, such as a Hall switch, which may be used as a commutation signal generator in a brushless DC motor. The two threshold voltages and hysteresis will be displayed on three digital voltmeters, The scale factors can be selected so that the voltmeters can be read directly in gauss.

The measuring instrument should include a magnetic field generator, a threshold sample pulse generator and a switching threshold sample and hold circuit.

Referring to Fig. 1, the magnetic field to actuate the Hall switch under test is produced by driving a magnetic coil with a 60 Hz current obtained from a step- down transformer T1, connected to the 60 Hz power line. The magnet has an air gap into which is inserted the Hall switch under test. The coil current is limited by resistor R1 in series with the magnetic coil. The magnetic field strength, which is proportional to the current through the coil, is measured by the voltage drop across resistor R2 and a portion of potentiometer P1. Potentiometer P1 is adjusted to produce the correct scale factor. This voltage will be termed "gauss" voltage hereafter.

The two signals from the magnetic field generator, which are shown in Fig. 2, consist of the digital output signal from the Hall effect switch under test and the gauss voltage (GV), which is an analog 60 Hz signal proportional t...