GB720151A - Improvements relating to impedance measuring devices - Google Patents
Improvements relating to impedance measuring devicesInfo
- 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
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring 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.
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)
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 |
-
1952
- 1952-06-18 GB GB1532052A patent/GB720151A/en not_active Expired
Cited By (1)
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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