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| Number | Title | Issue Date |
| 5479643 | Virtual machine programming system A system for programming a computer provides a set of software-based virtual machines each for instructing a computer to carry out a selected operation. Each virtual machine is represented by a virtual front panel displayed on a screen and each virtual fr... | 12/26/1995 |
| 5432706 | Multimeter having min/max time stamp A min/max time stamp for a multimeter provides display of minimum and maximum measured values recorded since enabling a min/max function. The minimum and maximum values, as well as a present value, may be displayed, together with the relative or absolute ... | 07/11/1995 |
| 5418450 | Coupling circuit for a measuring instrument A coupling circuit for a multimeter adapted to perform multiple measurements includes a thermistor and constant current sources in series between an instrument input terminal and an instrument circuit adapted to source current for ohms measurements. Varis... | 05/23/1995 |
| 5418464 | Thermocouple open circuit detection with tone frequency signal application and spectral analysis An improved open circuit detector for testing a thermocouple for an open circuit condition. The detector includes a generator for providing and sourcing a tone signal to the thermocouple, wherein the tone signal has a known frequency and amplitude. A moni... | 05/23/1995 |
| 5382910 | Dual time base zero dead zone time domain reflectometer A dual time base, zero dead zone time domain reflectometer repetitively launches a predetermined number of stimulus pulses into a transmission system in synchronism with clock signals from a first time base, providing a measurement cycle. The duration of ... | 01/17/1995 |
| 5379176 | Protective input circuit for an instrument A protective circuit for the input of a multimeter is provided with series connected thermistors partially shunted by a varistor whereby overload voltage is distributed between the thermistors enabling protection at higher voltage levels. Shunt connected ... | 01/03/1995 |
| 5365513 | Token ring local area network testing apparatus for matching its speed to ring speed A token ring local area network (LAN) testing apparatus is provided. The apparatus includes hardware and software that enables it to determine whether the testing apparatus is able to send frames into the token ring at a correct ring speed. The apparatus ... | 11/15/1994 |
| 5343164 | Operational amplifier circuit with slew rate enhancement A low power operational amplifier adjusts its output slew rate by providing additional bias current to its differential amplifier stage when the amplitude of the differential input signal exceeds a given threshold. The additional bias current provides an ... | 08/30/1994 |
| 5332963 | High input impedance buffer with low feedback resistance A high input impedance AC buffer for use in an instrument that does not require high frequency compensation or calibration. An op-amp receives an input signal that is to be measured via a high resistance input resistor and produces an output signal propor... | 07/26/1994 |
| 5325365 | In a memory emulation test apparatus, a method of and system for fast functional testing of memories in microprocessor-based units A memory emulation test system is provided with a method of and system for fast functional testing of memories, such as boot ROMs, in microprocessor-based assemblies. The emulative test system includes a synchronization circuit which automatically re-arms... | 06/28/1994 |
| 5321403 | Multiple slope analog-to-digital converter A multiple slope integrating analog-to-digital converter (ADC) includes many improvements and refinements which eliminate timing and non-linearity errors which accumulate due to a large number of switching operations that occur over an integrate cycle. Th... | 06/14/1994 |
| 5309428 | Token ring local area network testing apparatus for phase jitter testing A token ring local area network (LAN) testing apparatus is provided. The apparatus is able to conduct a phase jitter measurement without disruption of normal token ring operation. The apparatus transmits a frame that includes phase jitter test data. This ... | 05/03/1994 |
| 5291073 | Thermal power sensor A thermal power sensor for providing an output signal that is linearly related to the amount of power derived from a power source over a first range and that is square law related to the amount of power derived from a power source over a second range whic... | 03/01/1994 |
| 5227984 | Instrument with continuity capture feature An instrument having a continuity test feature wherein a change in continuity state from open-to-short or short-to-open is captured and displayed. A comparator provides continuity state information for a circuit under test. A storage device receives the s... | 07/13/1993 |
| 5218290 | Multi-function, multi-mode switch for an instrument A multi-function, multi-mode switch for an instrument that changes the instrument between primary and secondary functions and between first and second modes of operation within the primary and secondary functions. The instrument changes from the first mod... | 06/08/1993 |
| 5216387 | Noise reduction method and apparatus for phase-locked loops Method and apparatus for improving the signal-to-noise ratio of a divide-by-N phase-locked loop includes a variable divider circuit to provide a plurality of feedback signals of substantially equal phase. Each of the plurality of feedback signals includes... | 06/01/1993 |
| 5206796 | Electronic instrument with EMI/ESD shielding system An electronic instrument is provided with a shielding system consisting of two metallic shields press fitted into plastic instrument case parts without the need for any additional parts to provide electrical and mechanical attachment. In one embodiment, a... | 04/27/1993 |
| 5206650 | Charge-controlled integrating successive-approximation analog-to-digital converter A charge-controlled integrating successive-approximation analog-to-digital converter first stores a charge proportional to an unknown voltage in a manner similar to a dual-slope integrating ADC, and thereafter a successive-approximation binary search sequ... | 04/27/1993 |
| 5196980 | Low impedance, high voltage protection circuit A low impedance overvoltage protection circuit includes a first MOSFET having a drain connected to an input signal and a source connected to a drain of a second MOSFET, the source of the second MOSFET being coupled to the output. The gates of the first an... | 03/23/1993 |
| 5195096 | Method of functionally testing cache tag RAMs in limited-access processor systems A method of functionally testing cache tag RAMs in processor systems where the kernel is typically inaccessible. A test program first determines whether a fault exists at all within the cache tag RAM. If a fault is determined to exist, the faulty RAM loca... | 03/16/1993 |
| 5187647 | Electronic instrument keypad assembly with Z-axis oriented electrical interconnect A keypad structure includes a stiff backing element and an elastomeric cover that have between them a first membrane on which is defined a shorting conductive layer, a second membrane on which is defined a main conductive layer, the second membrane on whi... | 02/16/1993 |
| 5186634 | Electrical contact having spring-biased tabs for mounting to a circuit board An electrical contact having one or more spring-biased tabs for mounting to a circuit board precludes the need for additional mechanical fasteners and obviates any additional manufacturing steps, except for soldering. The tabs are formed and shaped to pro... | 02/16/1993 |
| 5146390 | LCD support bracket An LCD support bracket formed by a plurality of resilient contilever beams projecting from a support to the lower edge of the LCD panel. The opposite edge of the LCD panel is supported by an elastomeric interconnection member that electrically connects th... | 09/08/1992 |
| 5142221 | Automatic function selecting multimeter A digital multimeter having automatic function selection capability includes a signal type detector and an analog-to-digital converter formed as an application specific integrated circuit. The signal type detector has a comparator circuit that compares th... | 08/25/1992 |
| 5136251 | Capacitance measurement The capacitance of an unknown capacitor is measured with multimeter instrumentation employing a dual slope analog-to-digital converter. The initial voltage across the capacitor is measured and the capacitor is cyclically charged until the capacitor reache... | 08/04/1992 |
| 5136590 | Kernel testing interface and method for automating diagnostics of microprocessor-based systems An improved testing apparatus and method for testing the kernel of a microprocessor based unit under test (UUT) in which connection to the UUT is made at both the memory connection socket and at the microprocessor with the microprocessor being in place an... | 08/04/1992 |
| 5122627 | Asymmetrical electrical switch actuator An actutator for a multiple-position electrical switch includes an actuator member having a cam surface formed on its undersurface along each edge. Two pairs of cam followers formed at the end of respective resilient beams slide along the cam surface. The... | 06/16/1992 |
| 5119019 | Automatic function selecting multimeter Disclosed is a digital multimeter having an automatic function selection capability. The device includes a sensing circuit connected to its input to respond to the type of analog signal which is sensed and to provide logic signals which are characteristic... | 06/02/1992 |
| 5097198 | Variable power supply with predetermined temperature coefficient A power supply having an amplifier connected to first and second feedback circuits is provided in which the nominal output of the power supply is a function of the first and second feedback circuits and the temperature coefficient of the power supply is a... | 03/17/1992 |
| 5090918 | Isothermal termination block having a multi-layer thermal conductor 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... | 02/25/1992 |
| 5073757 | Apparatus for and method of measuring capacitance of a capacitive element An apparatus for and a method of measuring capacitance employs a charge measuring system. While a capacitive element, which may be an unknown capacitor, is charged completely to a predetermined voltage, a charge proportional to the capacitance of the capa... | 12/17/1991 |
| 5068852 | Hardware enhancements for improved performance of memory emulation method Addition of gated buffers which are accessible by the test apparatus microprocessor for receiving status information and the signals on some of the lines of the data bus of a microprocessor-based system under test provides the capacity for self testing, a... | 11/26/1991 |
| 5045817 | FM deviation control of direct digital synthesizers In a direct digital synthesizer providing a frequency modulated output the modulation input is bit shifted and the rate of the direct digital synthesizer phase accumulation is controlled to provide enhanced FM deviation resolution.... | 09/03/1991 |
| 5043655 | Current sensing buffer for digital signal line testing A current sensing buffer 26 for driving a digital signal line of a unit under test 12 is composed of current mirror circuits in series with output switching transistors supplying test signals to the digital signal line. The current mirror circuits 66, 72 ... | 08/27/1991 |
| 5028874 | Ratiometric measurement circuit with improved noise rejection A noise rejection circuit improves the signal-to-noise ratio of a ratiometric measurement circuit. A first operational amplifier produces a scaled-up voltage proportional to a low reference voltage. The scaled-up voltage is applied to a series connected r... | 07/02/1991 |
| 5027373 | N-pi phase/frequency detector A digital phase/frequency detector circuit in a phase locked loop comprises multiple bistable devices which are clocked up and down respectively by input and references digital signals to generate square waves. The duty ratio corresponds to the phase/freq... | 06/25/1991 |
| 5027063 | Vacuum-actuated test fixture for testing electronic components A miniature vacuum-actuated test fixture for testing individual components or localized areas of circuit boards includes a probe module having an array of probes carried by a piston, and a separable registration module which may be visually aligned over a... | 06/25/1991 |
| 4998072 | High resolution direct digital synthesizer The frequency resolution of a direct digital synthesizer is increased by varying the phase increment used to accumulate wave lookup table addresses between two integer values. The time periods during which the larger integer value is employed is proportio... | 03/05/1991 |
| 4992673 | Fast settling voltage to frequency converter for high speed analog to digital conversion A circuit arrangement reduces the time necessary for a voltage-to-frequency converter to provide a new output frequency in response to a change in input voltage levels. A current source provides additional input current to the input integrating node of th... | 02/12/1991 |
| 4991916 | Method and apparatus for automatically biasing a push-pull amplifier Method and apparatus are disclosed for automatically biasing a push-pull amplifier. Generally, the auto-biasing circuit of the present invention includes a resistor circuit for sensing the supply current to the push-pull amplifier. A control circuit respo... | 02/12/1991 |
