Abstract: For determining the air mass flow in the intake pipe of an internal combustion engine by means of an electrical bridge, normally the current flowing through the current measurement resistor when balancing the bridge is evaluated as an indirect measure of the air mass flow. The primary measured quantity for the air mass flow is, however, the power converted at the air flow measurement resistor around which the air flows so that the indirect measurement always includes an error. To reduce this measurement error, the invention utilizes the evaluation of the sum of the voltage across the current measurement resistor and the voltage or a partial-voltage across the air flow measurement resistor as a measure of the air flow.

Abstract: An IC fault analysis system which is capable of accurately correlating mask layout data and/or net listing data associated with CAD (computer aided design) data developed in the IC design and an image obtained by a non-contact type tester such as an electron beam tester.

Abstract: An automatic transistor checking method is provided, whereby an unknown, bipolar transistor may be typed, pinned and checked for forward DC gain, H.sub.fe. The method is suitable for portable instruments, because the method uses little battery current to perform the H.sub.fe measurement. The method automatically determines transistor type (NPN or PNP) and pinout, making it suitable for quick checking of batches of unknown devices.

Abstract: An instrument and method for measuring chemical properties, the instrument having electrodes suitable for immersion in a chemical solution. A voltage source and a current-sensing circuit are connected to the electrodes to measure the current produced in the solution in response to a voltage applied to the electrodes to determine a value of the chemical in the solution. The instrument and method further include background compensation for offsetting the value of the analyte by an amount which is reflective of the background value of the solution. The background value is stored in an internal memory of the instrument so that when new experimental measurements are taken, the measurements are immediately offset by the background portion of the new experimental measurements. This allows operation of the instrument at high gain levels, resulting in a broad dynamic range and greater useful precision in the output signal.

Abstract: A system (100) performs concurrent testing and lead verification of an electronic component (104) having two leads (126 and 128). The system includes circuitry (114 and 116) for determining a sum of amounts of contact resistances between first (132) and second (134) probes and one of the leads by producing a current (I.sub.1) that propagates through the first probe, the lead of the component, and the second probe. The sum of the contact resistances is proportional to the difference in voltage between the leads. If the difference exceeds a limit, then the sum of the amount of contact resistances is excessive. The system also includes circuitry (110) for determining a value of a parameter of the component while the sum of the amounts of contact resistances is being determined. The circuit for determining the sum of the contract resistances and the circuitry for determining the value of the parameter are electrically isolated from each other so that they do not influence each other.