A current detection circuit includes: a resistor in a current path; first and second signal transmission units that transmit signals of first and second terminal sides of the resistor; a first difference operation unit that executes a difference operation on the signals transmitted by the first and second signal transmission units; a noise-capturing transmission unit starting point; third and fourth signal transmission units connected with the noise-capturing transmission unit starting point; a second difference operation unit that executes a difference operation on the signals transmitted by the third and fourth signal transmission units; and a summing operation unit that executes a summing operation on the first and second difference signals, wherein the first signal transmission unit and the fourth signal transmission unit are disposed close to each other and the second signal transmission unit and the third signal transmission unit are disposed close to each other.

A current detection circuit includes: a resistor in a current path; first and second signal transmission units that transmit signals of first and second terminal sides of the resistor; a first difference operation unit that executes a difference operation on the signals transmitted by the first and second signal transmission units; a noise-capturing transmission unit starting point; third and fourth signal transmission units connected with the noise-capturing transmission unit starting point; a second difference operation unit that executes a difference operation on the signals transmitted by the third and fourth signal transmission units; and a summing operation unit that executes a summing operation on the first and second difference signals, wherein the first signal transmission unit and the fourth signal transmission unit are disposed close to each other and the second signal transmission unit and the third signal transmission unit are disposed close to each other.

A device for averaging a sensed current includes a sampling circuit that samples at least two sampling points of each cycle of a front-end alternating current (AC) sensed signal. The two sampling points is substantially symmetrical with respect to a midpoint of each respective cycle of the front-end AC sensed signal. The device also includes a timing circuit that controls a timing of the sampling circuit to sample the front-end AC sensed signal on the at least two sampling points based on a timing signal generated by the timing circuit. The device further includes an averaging circuit that averages the two sampling points for a given cycle of the front-end AC sensed signal to produce an average sensed current.

Systems and methods that provide a portable, verified voltage source that allows safe testing of separate contact and non-contact voltage measurement devices. A proving unit of the present disclosure selectively provides a known or specified direct current (DC) voltage, a contact alternating current (AC) voltage, and a non-contact AC voltage, which voltages may be fixed or may be user-selectable. The proving unit may include a visual indicator and/or an audible indicator that provides the user with an indication confirming that the proving unit is supplying the selected output voltage within the specifications of the proving unit, so the user will know that the proving unit is operating normally and is ready for testing the operation of a contact or non-contact voltage measurement device. If the proving unit cannot provide the specified voltage output, the indicator(s) provides a signal to the user that the proving unit is currently non-functional.

An absence of voltage indicator has an isolation circuit, an FM modulator attached to the isolation circuit, a reference oscillator, and a mixer attached to the reference oscillator and the FM modulator, wherein the output of the mixer is the difference of the two signals. In one embodiment, the FM modulator includes a variable capacitor which varies in response to a voltage in parallel to a fixed capacitor and an inductor in parallel to the capacitors.

An absence of voltage indicator has an isolation circuit, an FM modulator attached to the isolation circuit, a reference oscillator, and a mixer attached to the reference oscillator and the FM modulator, wherein the output of the mixer is the difference of the two signals. In one embodiment, the FM modulator includes a variable capacitor which varies in response to a voltage in parallel to a fixed capacitor and an inductor in parallel to the capacitors.

It is described an electronic device (1) for measuring an electric quantity, comprising: an analog-digital conversion module (2) configured to digitally convert time portions of an analog signal (S.sub.M(t)) to be measured alternated with time portions of a reference analog signal (S.sub.R(t)), for supplying respective first (D.sub.SM) and second pluralities (D.sub.SR) of digital values and a digital processing module (3) configured to: calculate a first mean amplitude (A1) of the first pluralities of digital values, and a second mean amplitude (A2) of the second pluralities of digital values; the first and second mean amplitudes being proportional to a mean gain value of the analog-digital conversion module (2); supply a ratio value (V.sub.RT) of the first mean amplitude to the second mean amplitude, representative of a measured amplitude of the analog signal (S.sub.M(t)) to be measured.

It is described an electronic device (1) for measuring an electric quantity, comprising: an analog-digital conversion module (2) configured to digitally convert time portions of an analog signal (S.sub.M(t)) to be measured alternated with time portions of a reference analog signal (S.sub.R(t)), for supplying respective first (D.sub.SM) and second pluralities (D.sub.SR) of digital values and a digital processing module (3) configured to: calculate a first mean amplitude (A1) of the first pluralities of digital values, and a second mean amplitude (A2) of the second pluralities of digital values; the first and second mean amplitudes being proportional to a mean gain value of the analog-digital conversion module (2); supply a ratio value (V.sub.RT) of the first mean amplitude to the second mean amplitude, representative of a measured amplitude of the analog signal (S.sub.M(t)) to be measured.

A current sensing apparatus may include a common mode core surrounding two or more current conductors and a current sensing element proximate the common mode core.

A current sensing apparatus may include a common mode core surrounding two or more current conductors and a current sensing element proximate the common mode core.