In one implementation, a circuit can include a reference pin and an operational amplifier that can include an output pin, an inverting input pin and a non-inverting input pin. The inverting input pin can be electrically coupled to the output pin via a first impedance and to the reference pin via a second impedance. The non-inverting input pin can be electrically coupled to the reference pin via a third impedance and can be configured to receive a detection signal. The reference pin can be configured to receive a detection reference signal associated with the detection signal.

Embodiments of the invention are directed to using a DC multimeter configured for checking device amperage. A DC voltmeter is electrically-connected in series with the DC multimeter. A linear circuit is electrically connected in series between the DC multimeter and the DC voltmeter. A device under test is electrically-connected between positive and negative terminals of the DC voltmeter.

A technique for testing an electronic UUT by a test apparatus includes obtaining multiple DFTs of a test signal received from the UUT with the test apparatus configured differently for obtaining each DFT. The resulting DFTs include both valid content representing the test signal and invalid content introduced by the test apparatus. The improved technique suppresses the invalid content by generating a corrected DFT, which provides minimum magnitude values for corresponding frequencies relative to the test signal across the multiple DFTs.

The invention involves a multimeter with a meter probe module and phasing probe module capable of wireless communication, proximity measurements, and accurately reading phase degrees. The meter probe module and the phasing probe module can communicate wirelessly, via a wired cable interface, or any combination thereof. The meter probe module and phasing probe module have unique radio frequency serial numbers that allow the probe modules to only communicate with its paired partner probe module while ignoring all other probe modules. The multimeter has a measurement point capable of taking direct contact measurements. The multimeter also has a measurement point capable of taking a voltage measurement without directly contacting the object to be measured. This is accomplished by taking voltage readings from the electric field of the air surrounding said object. The improved multimeter may allow an operator to more safely gather accurate information about an object being measured.

A method for in-situ measuring electrical properties of carbon nanotubes includes placing a first electrode in a chamber, wherein the first electrode defines a cavity. A growth substrate is suspend inside of the cavity, and a catalyst layer is located on the growth substrate. A measuring meter having a first terminal and a second terminal opposite to the first terminal is provided. The first terminal is electrically connected to the first electrode, and the second terminal is electrically connected to the growth substrate. A carbon source gas, a protective gas, and hydrogen are supplied to the cavity, to grow the carbon nanotubes on the catalyst layer. The electrical properties of the carbon nanotubes are obtained by the measuring meter.

A method for in-situ measuring electrical properties of carbon nanotubes includes placing a first electrode in a chamber, wherein the first electrode defines a cavity. A growth substrate is suspend inside of the cavity, and a catalyst layer is located on the growth substrate. A measuring meter having a first terminal and a second terminal opposite to the first terminal is provided. The first terminal is electrically connected to the first electrode, and the second terminal is electrically connected to the growth substrate. A carbon source gas, a protective gas, and hydrogen are supplied to the cavity, to grow the carbon nanotubes on the catalyst layer. The electrical properties of the carbon nanotubes are obtained by the measuring meter.

An overvoltage detection circuit coupled to an external power supply via a voltage supply line and comprising a transistor comprising first terminal coupled to the voltage supply line, second terminal coupled to the first terminal via a resistor, the second terminal coupled to a parasitic capacitor, the transistor configured to receive an overvoltage spike from the external power supply on the first terminal, and provide an output voltage on third terminal of the transistor to indicate detection of the overvoltage spike when it has a duration less than a time constant based on the resistor and the parasitic capacitor and amplitude that exceeds a threshold voltage of the transistor. The overvoltage detection circuit further comprises a monitor circuit configured to receive the output voltage from the transistor and provide a digital signal providing a notification of the detected overvoltage spike from the external power supply on the voltage supply line.

An electronic test measurement system can include a device under test (DUT) and an electronic test instrument that includes a signal input configured to receive an electrical signal from the DUT, a cooling mechanism, and a processor. The processor can be configured to determine a frequency at which the cooling mechanism should operate, cause the cooling mechanism to operate at the determined frequency, select a filter based on the determined frequency, and apply the filter to the electrical signal to reduce interference with the electrical signal resulting from mechanical vibrations of the cooling mechanism.

A digital multimeter stores multiple sequential measurements of physical or electrical parameters. Each of the sequential measurements has a name including an automatically generated descriptor. The descriptor for each sequential measurement may indicate a relative position of the measurement within the sequence. For instance, the descriptor may indicate whether the measurement was obtained before or after other measurements in the sequence.

An analytical gateway device receives measurement data comprising one or more measurement values from one or more measurement devices. The gateway device selects a measurement application from a plurality of measurement applications available for execution (e.g., on the gateway device or some other computing device) based at least in part on the measurement data. For example, the measurement application can be selected based on measurement type information. The measurement type information may include one or more measurement units associated with the measurement values. The gateway device may cause a user interface (or some other information) associated with the measurement application to be presented on a display (e.g., a display of the gateway device or some other computing device in communication with the gateway device).