Document Type and Number:
Japanese Patent JPS5412829
Kind Code:
B2
Abstract:
The unbalance of a measuring bridge is measured by means of a frequency variation or period variation of an oscillator. The measuring bridge may, for example, be a four-arm strain-gage bridge. In order to assure a linear conversion of the unbalance, which represents the quantity to be measured, into a frequency or period variation two control loops are required. One loop injects an unbalance compensation current into the bridge via a null balancing system. The variations in the latter system cause a variation of the frequency of an oscillator via, for example, the resistance variation of a photo-sensitive resistor. The second loop ensures that a second equivalent impedance in the frequency-determining network influences the oscillator in the same way, so that the square root of the two impedances yields the linear relationship. The invention indicates how by the choice of the oscillator the control loops can be simplified, for example, by using multiplier circuits as variable potentiometers, and how in a simple manner either a frequency variation or a period variation can be obtained as a measuring result.
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Application Number:
JP3341373A
Publication Date:
May 25, 1979
Filing Date:
March 23, 1973
Export Citation:
International Classes:
G01R17/16; G01D5/243; G01R19/25; G01R19/252; G01R19/255; H03B5/26; H03B5/38; H03B27/00