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公开(公告)号：US4321530A
公开(公告)日：1982-03-23
申请号：US56729
申请日：1979-07-11
IPC分类号： G01R15/12 , G01R19/145 , G01R15/08 , G01R19/16
CPC分类号： G01R19/145 , G01R15/125
摘要： A digital multimeter having a tone generating circuitry and operable in a tone mode of operation for providing an audible indication when a measured electrical characteristic has a predetermined relationship with a reference value. The audible indication may be provided when a voltage level exceeds a preselectable limit, such as 1 or 2 volts. Predetermined limits for resistance values may also be selected for actuation of the audible tone. The device may be utilized as a conventional multimeter when the tone mode is non-operative.
摘要翻译： 一种数字万用表，其具有乐音产生电路，并且可以在音调操作模式下操作，以便在测量的电特性与参考值具有预定关系时提供可听见的指示。 当电压电平超过预置极限（例如1或2伏特）时，可以提供可听见的指示。 还可以选择电阻值的预定极限以用于致动可听音。 当音调模式不工作时，该装置可以用作常规的万用表。
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公开(公告)号：US4520310A
公开(公告)日：1985-05-28
申请号：US389723
申请日：1982-06-18
CPC分类号： G01R15/125 , G01R15/09
摘要： 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.
摘要翻译： 用于电压测量和显示设备的电路可以对AC或DC电压的测量提供自动功能更改。 假设在预定模式（例如DC）中的电压测量。 当检测到超过另一模式的预定阈值的输入电压分量（例如，AC）时，测量功能被改变为该另一模式。 在另一模式中检测到组件时，在预定阈值和第二（优选较低））阈值之间的范围内，激活报警器以警告用户存在其他模式（AC）电压，以便手动激活 如果需要的话功能选择开关。 因此，在具体实施例中，在检测到超过预定阈值的AC分量以及AC信号器的激活时，提供自动功能切换。 或者，在测量的直流电压上存在低幅度交流纹波电压分量的情况下，信号器被激活以引起操作者的注意，测量继续在直流功能中。
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3.发明授权Digital thermometer using a dual slope A/D converter without a high precision voltage source 失效数字温度计使用双斜率A / D转换器，没有高精度电压源
公开(公告)号：US3978471A
公开(公告)日：1976-08-31
申请号：US562194
申请日：1975-03-26
申请人： Austin T. Kelly
发明人： Austin T. Kelly
摘要： A measuring device such as a digital thermometer uses dual slope analog-to-digital converter techniques but elminates the usual need for a high precision voltage source. An input capacitor is connected through novel switching to the temperature responsive arm and the temperature insensitive arm of a resistance bridge, to the low precision voltage source and to the output of the integrator and detector amplifiers. The switching sequence is such that long term changes in the voltage source and in the amplifier offset and drift are cancelled out during measurement cycles, thereby providing highly accurate measurements without the usual need for an expensive high precision voltage source.
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4.发明授权
公开(公告)号：US3958236A
公开(公告)日：1976-05-18
申请号：US534149
申请日：1974-12-18
申请人： Austin T. Kelly
发明人： Austin T. Kelly
摘要： A dual slope analog-to-digital converter, which has an autozeroing circuit for cancelling out integrator and detector offset and drift, is additionally provided with a circuit for injecting a voltage of selected polarity and magnitude to offset the input voltage of the converter such that the input voltage can be measured with respect to a nonzero reference line.
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