Patent US2193784A successfully refreshed from Google Patents.
US3746984A
Expired / Lapsed
US
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Autopolarity voltmeter circuit
Assignee: Triplett Corp
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Filing: 1970-09-08
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Granted: 1973-07-17
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Expires: 1990-09-08
Abstract
Abstract A highly-sensitive circuit for an electrical instrument for causing the indicator on a meter to read linearly upscale for positive or negative DC signals, AC signals, or a combination of AC or DC signals applied to the input of the circuit. The input signal to be measured is provided to an input circuit which includes a resistive divider network in circuit with a null control circuit for selecting the range of input signals. A selected proportion of the input signal is applied to the input of a field effect transistor (FET). The output from the FET is applied to the input of a transistor having its output in circuit with a bridge network. The bridge network includes a pair of oppositely poled diodes in circuit with fixed resistors so that a first diode conducts for positive signals and a second diode conducts for negative signals from the transistor. A meter is connected in circuit with the diodes and is arranged so that the indicator on a meter reads upscale whether the output of the amplifier comprises positive or negative DC signals or AC signals or a combination of both. A feedback circuit includes a resistive network in circuit with the bridge for selecting the appropriate circuit sensitivity for the function to be performed by the circuit. The output from the resistive network in the feedback path is connected to a pair of transistors connected in a Darlington configuration, the output of which is connected to the FET. The input circuit also includes a switching circuit for providing a coupling capacitor in series circuit with the input signals to block DC when AC signals are being measured, and to provide a low pass filter in circuit with the input signals when DC signals are being measured. The circuit according to the invention may be also be used to measure resistance and current. The method of using the circuit of the invention is also disclosed wherein the indicator on the meter is caused to indicate a null reading in the absence of an input signal to the circuit by adjusting the null control circuit and sensing the indicator on the meter until a null is reached. The null control circuit may also be used to provide a storage feature for the circuit.
Inventors
- 👤 W Cerveny
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 02:14
CPC Classifications
G; G01; G01R; G01R15/00; G01R15/08; G01R15/09
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
190 words
A high input impedance circuit for an electrical instrument capable of receiving an input signal which is either positive or negative with respect to a datum signal level and providing a unidirectional physical representation thereof for either polarity comprising: input means for receiving said input signal indicative of a sensed parameter to be measured; means for amplifying said input signal to provide an output signal which is a representation of said sensed parameter; output means, comprising a meter which includes means for providing said unidirectional physical representation of the magnitude of a signal applied to said meter irrespective of the polarity of the applied signal, for receiving said output signal from said amplifying means and applying said output signal to said meter in such a manner that said physical representation is unidirectional with respect to a datum signal level for output signals which are either positive or negative or a combination thereof with respect to a second datum signal level; and means for indicating whether said input signal is positive or negative with respect to said datum signal level by altering the magnitude of the physical representation on said meter.
Claim 2
Dependent Claim
190 words
A high input impedance circuit for an electrical instrument capable of receiving an input signal which is either positive or negative with respect to a datum signal level and providing a unidirectional physical representation thereof for either polarity comprising: input means for receiving said input signal indicative of a sensed parameter to be measured; means for amplifying said input signal to provide an output signal which is a representation of said sensed parameter; output means, comprising a meter which includes means for providing said unidirectional physical representation of the magnitude of a signal applied to said meter irrespective of the polarity of the applied signal, for receiving said output signal from said amplifying means and applying said output signal to said meter in such a manner that said physical representation is unidirectional with respect to a datum signal level for output signals which are either positive or negative or a combination thereof with respect to a second datum signal level; and means for indicating whether said input signal is positive or negative with respect to said datum signal level by altering the magnitude of the physical representation on said meter.
Claim 3
Dependent Claim
28 words
The circuit as defined in claim 1 wherein said input means includes a device for sensing a parameter to be measured and providing an output signal indicative thereof.
Claim 4
Dependent Claim
45 words
The circuit as defined in claim 1 wherein said output means includes a first unidirectionally conductive device and a second unidirectionally conductive device, each of which is connected in circuit with said amplifying means for receiving said output signal and in circuit with said meter.
Claim 5
Dependent Claim
48 words
The circuit as defined in claim 3 wherein each of said unidirectionally conductive devices is a diode arranged so that one of said diodes conducts for an output signal having a first polarity and the other of said diodes conducts for an output signal of a second polarity.
Claim 6
Dependent Claim
97 words
The circuit as defined in claim 4 wherein said indicating means includes a first switch in circuit with said one diode and a second switch in circuit with said other diode for selectively shunting the output signal from said amplifying means across the diode with which the switch is associated, whereby closure of one of said first switch and said second switch without changing the representation on said meter indicates that said input signal is positive and the closure of the other switch indicates that said input signal is negative by changing the representation on said meter.
Claim 7
Dependent Claim
23 words
The circuit as defined in claim 5 wherein said output means further includes a balance resistor in circuit with each of said diodes.
Claim 8
Dependent Claim
36 words
The circuit as defined in claim 6 wherein the output meAns further includes means for selecting one of a plurality of resistances, each of which corresponds to a sensing function to be performed by the circuit.
Claim 9
Dependent Claim
40 words
The circuit as defined in claim 1 further including voltage feedback means in circuit with said output means and said amplifying means and said circuit is characterized as having an input impedance in the order of better than 10 megohms.
Claim 10
Dependent Claim
51 words
The circuit as defined in claim 8 wherein said feedback means includes selectively variable resistance means and feedback amplifier means in circuit therewith, said variable resistance means being in circuit with said output means and said feedback amplifier means is in circuit with said variable resistance means and said amplifying means.
Claim 11
Dependent Claim
31 words
The circuit as defined in claim 9 wherein said feedback amplifier means includes a pair of transistors connected in a Darlington configuration to couple the output means to the input means.
Claim 12
Dependent Claim
62 words
The circuit as defined in claim 10 wherein said amplifying means includes a field effect transistor having a gate, a source, and a drain, the gate of said field effect transistor being connected in circuit with said input signal and the source of said field effect transistor being connected in circuit with the output of one of said pair of Darlington-connected transistors.
Claim 13
Dependent Claim
34 words
The circuit as defined in claim 1 further including means for varying the said physical representation of said meter so that said physical representation is set at a predetermined position for a predetermined condition.
Claim 14
Dependent Claim
32 words
The circuit as defined in claim 12 wherein said predetermined condition is the absence of an input signal to the circuit and said predetermined position is a null reading on said meter.
Claim 15
Dependent Claim
32 words
The circuit as defined in claim 12 wherein said predetermined condition is the absence of an input signal to the circuit and said predetermined position is a predetermined reading on said meter.
Claim 16
Dependent Claim
33 words
The circuit as defined in claim 12 wherein said predetermined condition is the presence of a first input signal to the circuit and said predetermined condition is a null reading on said meter.
Claim 17
Dependent Claim
190 words
In a circuit for an electrical instrument of the multimeter type which is capable of at least receiving an input signal which is either positive or negative with respect to a datum signal level and providing a unidirectional physical representation of the magnitude of said input signal irrespective of the polarity of said input signal and which includes a source of input signals, means for amplifying an input signal to provide an output signal, and a meter which includes an indicator, the improvement comprising autopolarity means for causing said indicator to read upscale for output signals having either positive or negative components or a combination thereof, said means comprising a bridge network which includes a pair of diodes, each of said diodes being in circuit with a resistance so that a diode and a resistance comprise each leg of the bridge network, said meter being connected between the respective junctions common to a diode and a resistance, said autopolarity means including means for indicating whether said input signal is positive or negative with respect to said datum signal level by altering the magnitude of the physical representation on said meter.
Claim 18
Dependent Claim
190 words
In a circuit for an electrical instrument of the multimeter type which is capable of at least receiving an input signal which is either positive or negative with respect to a datum signal level and providing a unidirectional physical representation of the magnitude of said input signal irrespective of the polarity of said input signal and which includes a source of input signals, means for amplifying an input signal to provide an output signal, and a meter which includes an indicator, the improvement comprising autopolarity means for causing said indicator to read upscale for output signals having either positive or negative components or a combination thereof, said means comprising a bridge network which includes a pair of diodes, each of said diodes being in circuit with a resistance so that a diode and a resistance comprise each leg of the bridge network, said meter being connected between the respective junctions common to a diode and a resistance, said autopolarity means including means for indicating whether said input signal is positive or negative with respect to said datum signal level by altering the magnitude of the physical representation on said meter.
Claim 19
Dependent Claim
60 words
The circuit as defined in claim 16 wherein said bridge network includes a terminal for receiving said output signal, a first diode having its anode in circuit with said first terminal and its cathode in circuit with said meter, and a second diode having its cathode in circuit with said first terminal and its anode in circuit with said meter.
Claim 20
Dependent Claim
25 words
The circuit as defined in claim 17 further including a variable impedance in circuit with said first diode and said second diode through said resistances.
Claim 21
Dependent Claim
64 words
The circuit as defined in claim 1 wherein said input means includes: a capacitor for coupling said input signal to said amplifying means; a low pass filter for filtering AC Components from said input signal; and switching means for selectively inserting either said capacitor or said low pass filter in circuit with said input signal when AC or DC signals respectively are being measured.
References Cited (Backward Citations)
US1254620A
Cited
US1689660A
Cited
US2364687A
Cited
US2764737A
Cited
US2870408A
Cited
US3211995A
Cited
US2944215A
Cited
US2939067A
Cited
US3311826A
Cited
US3398369A
Cited
US3421982A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-07-16 | 1977-01-15 | 1977-07-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-16 | 1981-01-15 | 1981-07-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-16 | 1985-01-15 | 1985-07-17 | $7700.00 | Window Closed / Lapsed |