GB720151A - Improvements relating to impedance measuring devices - Google Patents

Improvements relating to impedance measuring devices

Info

Publication number
GB720151A
GB720151A GB1532052A GB1532052A GB720151A GB 720151 A GB720151 A GB 720151A GB 1532052 A GB1532052 A GB 1532052A GB 1532052 A GB1532052 A GB 1532052A GB 720151 A GB720151 A GB 720151A
Authority
GB
United Kingdom
Prior art keywords
capacity
voltage
electrode
impedance
rectifier circuits
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
GB1532052A
Inventor
John Ernest Fielden
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Fielden Electronics Ltd
Original Assignee
Fielden Electronics Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Fielden Electronics Ltd filed Critical Fielden Electronics Ltd
Priority to GB1532052A priority Critical patent/GB720151A/en
Publication of GB720151A publication Critical patent/GB720151A/en
Expired legal-status Critical Current

Links

Classifications

    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R27/00Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
    • G01R27/02Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Measurement Of Resistance Or Impedance (AREA)

Abstract

720,151. Capacitance measurement; detecting changes in the proximity or nature of surrounding objects. FIELDEN (ELECTRONICS), Ltd. Sept. 17,1953 [June 18, 1952], No. 15320/52. Class 37. The impedance to be measured causes a difference voltage to appear across two rectifier circuits whereupon a motor responsively to this voltage drives a variable impedance in one of the rectifier circuits until the difference voltage is zero. The extent to which the variable impedance is adjusted is a measure of the unknown impedance. The rectifier circuits are fed with low-frequency (e.g. mains) modulated oscillations. The invention is described with reference to capacitance measurement. In the embodiment shown pick-up coils L2, L3 receive from a Hartley oscillator A radiofrequency oscillations modulated at mains or supply frequency and L2 is connected to a capacity electrode by a screened lead B. The coils L2, L3 respectively feed series-connected junction-earthed load resistors R1, R1A through rectifiers X1-X3 and X4-X6 preceded by phase-adjusting combinations L4, C5 and L5, C6 and variable capacitors CV1 and CV2, CV3. The R.F. carrier is filtered out by C1, C2 and normally equal and opposite voltages demodulated at supply frequency appear across R1, R1A. The capacity of the electrode varies with changes in the proximity or the nature of the surrounding objects and CV1 is scaled in appropriate units. To condition the apparatus for use, CV1 is set to maximum capacity with the test electrode at minimum capacity and CV2, CV3 giving coarse and fine control respectively are adjusted until zero voltage exists across the outers of R1, R1A. If the electrode capacity increases the R1 voltage exceeds that of R1A and the difference via transformer/amplifier/transformer T1/D/T2 operates reversible motor M and the latter adjusts CV1 to zeroize the difference voltage. The motor M is damped by D.C. drawn from rectifier E. The apparatus may be used for measuring the capacity of a test capacitor connected across CV1.
GB1532052A 1952-06-18 1952-06-18 Improvements relating to impedance measuring devices Expired GB720151A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB1532052A GB720151A (en) 1952-06-18 1952-06-18 Improvements relating to impedance measuring devices

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB1532052A GB720151A (en) 1952-06-18 1952-06-18 Improvements relating to impedance measuring devices

Publications (1)

Publication Number Publication Date
GB720151A true GB720151A (en) 1954-12-15

Family

ID=10056995

Family Applications (1)

Application Number Title Priority Date Filing Date
GB1532052A Expired GB720151A (en) 1952-06-18 1952-06-18 Improvements relating to impedance measuring devices

Country Status (1)

Country Link
GB (1) GB720151A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3175151A (en) * 1959-05-21 1965-03-23 Bertram Mccarthy Electrical circuit means for sensing an intermittent change in capacity between a probe and earth

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3175151A (en) * 1959-05-21 1965-03-23 Bertram Mccarthy Electrical circuit means for sensing an intermittent change in capacity between a probe and earth

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