Abstract: Generally described, one or more embodiments of the present disclosure are directed to switch assemblies and methods for switching from one state to another. In some examples, a switch assembly may switch from one electrical contact to another electrical contact by moving a conductive spring or member from a first conductive contact on a printed circuit board (PCB) to a second conductive contact on the PCB. For instance, in one embodiment, a conductive member moves within a slot in the PCB. In another embodiment, a compression force applied to a conductive spring is reduced while the conductive spring moves from a first conductive contact to a second conductive contact.

Abstract: Generally described, one or more embodiments of the present disclosure are directed to switch assemblies and methods for switching from one state to another. In some examples, a switch assembly may switch from one electrical contact to another electrical contact by moving a conductive spring or member from a first conductive contact on a printed circuit board (PCB) to a second conductive contact on the PCB. For instance, in one embodiment, a conductive member moves within a slot in the PCB. In another embodiment, a compression force applied to a conductive spring is reduced while the conductive spring moves from a first conductive contact to a second conductive contact.

Abstract: A low error, switchable measurement lead detect circuit (9) for providing accurate current measurement readings and reducing susceptibility to false measurement lead detections due to leakage current is described. A gate (14) that receives an input select voltage Vs selectively connects either a supply voltage, Vd, or ground to the input of a voltage divider (13). Vd is connected during a measurement lead detection mode of operation or open fuse detection mode of operation, and a ground is connected during a current measurement mode of operation. During the measurement lead detection mode of operation, if the pin of a measurement lead is present in a split jack (12), the voltage divider (13) divides the supply voltage, Vd. Conversely, if no measurement lead pin is present in the split jack (12), the output voltage, Vo, of voltage divider (13) equals the level of Vd.

Abstract: An improved capacitance measurement system employs a selectable constant current source which is switched into a capacitor in a charge measurement system. The capacitor produces a linear ramp voltage in response to the constant current. An analog-to-digital converter (ADC) measures the change in voltage along the ramp over a corresponding change in time. These values, together with the value of constant current, are used to calculate the capacitance. In the preferred embodiment, a multi-slope ADC is utilized for the measurement. This system offers a wide range of measurable capacitance, and is fast responding and accurate. In addition, visual feedback to the user on measurement progress can be provided, which is particularly advantageous when measuring large capacitors.

Abstract: An overvoltage and transient protection circuit with extended bandwidth is provided for the protection of a low voltage test signal path (210) such as a test signal path in a multimeter. The disclosed circuit maintains the integrity of a test signal (TS) (114) transmitted by the test signal path (210) by minimizing the effect that unwanted capacitive coupling would otherwise have on the frequency transmission capability of the circuit. During normal operation of the circuit, a test signal path isolation circuit (218) is held between the test signal (TS) (114) and an equivalent buffered guard signal (GS) 227. Held between these equivalent values (TS=GS), no (or minimal) current will be generated in the components of the test signal path isolation circuit (218) as a result of parasitic capacitance. The guard signal (65) (227) is used with guard traces (412) and guard planes (414) to isolate other parts of the test signal path in much the same way.

Abstract: An input ranging circuit for an electronic instrument that allows for measuring a.c. voltage, d.c. voltage, and d.c. resistance is provided. The voltage ranging circuit has three modes, d.c. volts, a.c. volts, and ohms, which are selected by a mode switch. A resistor network containing an input resistor, feedback resistors, a reference resistor, and divider resistors provides resistances that are ratiometrically scaled to maintain relatively tight ratio tolerances. A switch array coupled to the resistor network provides for the selected circuit configuration and divider ratio in conjunction with the mode switch. Each of the switches in the switch array may be independently controlled via control signals. In d.c. volts mode, the input voltage is divided down according to a desired voltage divider ratio. In a.c. volts mode, the voltage divider is supplemented with an a.c. amplifier configured to extend the useful bandwidth of the input ranging circuit.

Abstract: A reference voltage support circuit that interfaces with a variety of reference voltage circuit types including bandgap references, zener references, and reference amplifiers with only the interconnection details being different. The reference voltage support circuit contains a voltage source to produce a stabilized supply current for the reference voltage circuit and a unity gain voltage inverter to produce both positive and negative reference voltages from a unipolar reference voltage circuit. The current source and the unity gain voltage inverter both employ ratiometrically scaled resistor networks coupled to the negative and positive reference voltages for high stability over time and temperature.

Abstract: An isothermal block has a multi-layer thermal conductor interleaves with different layers of a printed circuit board to provide improved thermal coupling of input terminals and a local temperature sensor mounted on the isothermal block. Each of the layers of the thermal conductor is substantially thinner than substrate layers of the printed circuit board. The layers of the thermal conductor are spaced apart from the terminals so as to be electrically isolated from the terminals. Embedded layers of the thermal conductor are spaced closer to the terminals than are external layers of the thermal conductor.