Autofunction voltmeter
First Claim
1. In a measuring device for an input voltage, which device has an input voltage means for receiving the input voltage, an AC to DC converter means for providing a DC output voltage, and a measurement and display means;
- a circuit structure for changing operating function between AC and DC measuring and display modes, which circuit structure is operatively connected with the input voltage means, the AC to DC converter means, and the measurement and display means, the circuit structure comprising;
comparing means connected for comparing a portion of the input voltage with a first reference voltage and for providing an output signal having states indicative of the result of the comparison,controlled switching means responsive to the output signal of said comparing means for connecting and disconnecting the output voltage of the AC to DC converter means to and from, while at substantially the same time disconnecting and connecting the input voltage from and to, the measurement and display means,whereby input voltages are automatically measured and displayed as AC voltages with AC to DC conversion whenever the input voltages have an AC component of a particular relation to the first reference voltage.
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Accused Products
Abstract
Circuitry for use in a voltage measurement and display device provides automatic function change for measurement of AC or DC voltages. Voltage measurement in a predetermined mode (DC, for example), is assumed. Upon detection of an input voltage component exceeding a predetermined threshold of the other mode, (AC, for example), the measurement function is changed to that other mode. Upon detection of a component in the other mode, in a range between the predetermined threshold and a second (preferably lower) threshold, an annunciator is activated to alert the user to the presence of the other mode (AC) voltage, for manual activation of a function-selecting switch if desired. Thus, in a specific embodiment, automatic function changeover is provided upon detection of AC components exceeding a predetermined threshold, along with activation of an AC annunciator. Alternatively, in the presence of low magnitude AC ripple voltage components on a DC voltage being measured, the annunciator is activated to attract the operator'"'"'s attention, with measurement continuing in the DC function.
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Citations
15 Claims
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1. In a measuring device for an input voltage, which device has an input voltage means for receiving the input voltage, an AC to DC converter means for providing a DC output voltage, and a measurement and display means;
- a circuit structure for changing operating function between AC and DC measuring and display modes, which circuit structure is operatively connected with the input voltage means, the AC to DC converter means, and the measurement and display means, the circuit structure comprising;
comparing means connected for comparing a portion of the input voltage with a first reference voltage and for providing an output signal having states indicative of the result of the comparison, controlled switching means responsive to the output signal of said comparing means for connecting and disconnecting the output voltage of the AC to DC converter means to and from, while at substantially the same time disconnecting and connecting the input voltage from and to, the measurement and display means, whereby input voltages are automatically measured and displayed as AC voltages with AC to DC conversion whenever the input voltages have an AC component of a particular relation to the first reference voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
- a circuit structure for changing operating function between AC and DC measuring and display modes, which circuit structure is operatively connected with the input voltage means, the AC to DC converter means, and the measurement and display means, the circuit structure comprising;
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12. In a measuring device for an input voltage, the device having an input voltage means for receiving a voltage to be measured, an AC to DC converter means operatively connected to the input voltage means for providing a DC output voltage, and a measurement and display means having function annunciator means for indicating the nature of the measured voltage as AC or DC;
- a circuit structure for activating a specific annunciator to indicate measurement of a specific type of voltage, the circuit structure being operatively connected with the input voltage means, the AC to DC converter means, and the measurement and display means;
the circuit structure including;first means for measuring a first type of voltage; second means for measuring a second type of voltage; control means connected to one of said first and second measuring means for controlling the specific annunciator to operate in a first mode when said first type of voltage is being measured, in a second mode when said second type of voltage is being measured, and in a third mode when a voltage having a small component of said first type is being measured. - View Dependent Claims (13, 14)
- a circuit structure for activating a specific annunciator to indicate measurement of a specific type of voltage, the circuit structure being operatively connected with the input voltage means, the AC to DC converter means, and the measurement and display means;
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15. A device for measuring an input voltage, the device comprising:
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an input voltage means for receiving the input voltage; an AC to DC converter operatively connected to the input voltage means for providing a DC output voltage; a comparing means operatively connected with the AC to DC converter for comparing the converter DC output voltage with a first reference voltage and providing a comparing means output signal indicative of the result of the comparison; a measurement and display means for converting a received voltage to a man-readable display indicative of the magnitude thereof, the measurement and display means including an annunciator for indicating whether AC or DC voltage is being measured; controlled switching means responsive to the comparing means output signal for selectively connecting the measurement and display means with one of the AC to DC converter and the input voltage means, while substantially simultaneously disconnecting the measurement and display means from the other of the input voltage means and the AC to DC converter, the controlled switching means being operatively connected with the measurement and display means and the comparing means; and
,an annunciator control means operatively connected to at least one of the input voltage means and the AC to DC converter for controlling the annunciator to operate in a first mode when the AC voltage is being measured, in a second mode when DC voltage is being measured, and in a third mode when DC voltage having a small AC component is being measured, the annunciator control means being operatively connected with the measurement and display means.
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Specification