Autofunction voltmeter

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.

A device for measuring an input voltage, the device comprising:

• 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.