Abstract: A power failure indicator circuit for a pulse width modulated power supply compares the averaged voltage of the pulse width modulated signal to an input reference voltage to determine if power failure of the supply will occur. The reference voltage corresponds to a predetermined proportion of the maximum average voltage of the pulse width modulated signal. In a preferred embodiment, the pulse width modulated signal is inverted and filtered to generate an averaged signal corresponding to the DC input voltage to the modulator within the pulse width modulated power supply. A comparator compares the averaged signal voltage to the reference voltage to determine if the averaged signal voltage level has fallen below the reference voltage level. If the averaged signal voltage level does drop below the reference voltage level, the comparator generates a signal warning of power failure of the power supply.

Abstract: A new and efficient method for attaching an optical fiber to a substrate to form a structurally secure optical fiber package is disclosed. The method first involves coating an optical fiber with an external layer of gold. A silicon retaining member is then provided having a groove therein sized to retain and receive the coated optical fiber. The silicon retaining member and optical fiber are then positioned on a substrate preferably constructed of alumina. Deposited on the substrate is at least one metal pad having an external gold layer on which the silicon retaining member is placed. The optical fiber, silicon retaining member, and substrate are then heated at a temperature sufficient to form a silicon/gold eutectic alloy between th silicon of the retaining member and the gold layers of the optical fiber and pad. Such heating involves a temperature of at least 370.degree. C. Heating is preferably accomplished using a resistor secured to the underside of the substrate.

Abstract: A probe for a logic analyzer includes a replacement plug assembly comprising those portions of probe equipment which must be specifically adapted to accommodate a selected microprocessor, and a buffer probe assembly comprising those portions of probe equipment which are adapted for use with a wide variety of microprocessors. The replacement plug assembly and the buffer probe assembly are mechanically joined and electrically coupled by a square pin connector so that the replacement plug assembly may be removed from the probe and replaced with a differently configured replacement plug assembly when a different microprocessor is to be probed. Thus only a portion of the probe is changed to retarget the probe for different microprocessors.

Abstract: A lumped-parameter, electrical delay line having shunt capacitance including variable-capacitance diodes. A tuning voltage applied to the diodes provides electrically variable delay at low jitter and stable insertion delay.

Abstract: A current source utilizes N+1 transistors to produce N output currents of magnitudes proportional to a variable reference current. Each transistor emitter is resistively coupled to a common potential and each transistor base is driven by a common control voltage, offset by a separately adjustable amount for each transistor. The control voltage is produced by an amplifier having a grounded inverting input and a non-inverting input coupled to the collector of a first of the transistors and resistively coupled to a variable reference voltage source. The reference voltage source is adjusted to produce a desired reference current in the collector of the first transistor and the magnitude ratio of an output current produced in the collector of each of the N remaining transistors to the reference current is controlled by adjusting the ratio of emitter resistance of the first transistor to the emitter resistance of the remanining transistors.

Abstract: A circuit for converting an input logic signal to an output logic signal having differing high and/or low logic voltage levels includes an output transistor and a load resistor coupling a collector of the output transistor to a supply voltage. The emitter of the output transistor is grounded. An input stage clamps a base of the output transistor to ground when the input signal voltage level is low, thereby turning the output transistor off and allowing the load resistor to pull the output signal, produced at the output transistor collector, up to its high logic level. When the input signal is high, the input stage unclamps the base of the output transistor from ground and a feedback stage responsive to the output signal supplies feedback current to the base of the output transistor, which feedback current increases with the magnitude of the output logic signal. The feedback current turns on the transistor, thereby increasing load current through the load resistor so as to reduce the output signal level.

Abstract: A modularized packaging system for enclosing circuit components of an electronic instrument. That system includes one or more "C" frame modules each having top, bottom and side wall portions interconnected one to the other orthogonally. In addition, there is provided interconnection means for interconnecting, side by side, as many of the "C" frame modules as desired with a side panel provided for closing the outwardly facing open sides, if any, of the outermost "C" frame modules. To complete the package, front and rear end assemblies are provided to close those portions of the interconnected "C" frame modules.

Abstract: A touch panel has panel scanning signals selectively applied to the four sides of a touch sensing surface of the panel so as to establish alternating current voltage gradients in desired directions across the touch sensing surface. When the panel is touched, touch signals result and are utilized by a touch location circuit in determining the location of touch. The impedence touch current resulting from a user's touch may also be determined and used. The touch panel circuit automatically adjusts the frequency of the applied panel signals to shift this frequency away from fixed frequency interference spectra, such as due to cathode-ray tube flyback signals, in the environment in which the touch panel is used. The touch location thereby minimizes the effects of such spectra on touch location determinations.

Abstract: A touch panel has panel scanning signals selectively applied to the four sides of a touch sensing surface of the panel so as to establish alternating current voltage gradients in desired directions across the touch sensing surface. When the panel is touched, touch signals or currents result and are utilized by a touch location circuit in determining the location of touch. The impedance touch current resulting from a user's touch may also be determined and used. The touch panel circuit automatically compensates for changes in impedance touch current, such as result when users touch the panel with ungloved and gloved fingers. An analog multiplier is included in the touch location circuit to improve noise rejection. Auto nulling and automatic frequency adjustment is included in the touch panel device, together with overcurrent protection circuitry.

Abstract: A power amplifier circuit for driving an inductive load comprises a capacitor coupled between first and second circuit nodes, a first unidirectionally-conductive device having a first terminal coupled to the first circuit node, and a transistor having its collector coupled to the second terminal of the first unidirectionally-conductive device and having its emitter coupled to the second circuit node. The direction of conduction of the first unidirectionally-conductive device is the same as the direction of conduction through the collector-emitter path of the transistor. The circuit also comprises a second unidirectionally-conductive device connected in parallel with the first unidirectionally-conductive device for conducting current in the opposite direction from the direction of conduction of the first unidirectionally-conductive device.

Abstract: A method for mounting electrical components or wires having connections both on and off circuit boards is provided in which the component is machine inserted and flow soldered along with other parts. Leads to be connected off the board are inserted into dummy holes, i.e., holes having no metallic pads or plating, so that these leads are not bonded to the board during the flow solder process. In the final assembly stage, the unbonded leads are raised from the board and electrically and mechanically connected to a terminal of an off-board component.

Abstract: A method of mounting support pads to rigid instrument casings, e.g. of metal or plastic. The pads are formed with flange portions designed to be force fit through a hole in the casing. The hole is provided with a key way or cutout. The corner that is formed at the juncture with the hole is outwardly angled and the opposite corner is inwardly angled. The flange of the pad is inserted under the outwardly angled corner and the pad is turned to wrap the flange around and under the hole edge.

Abstract: A high frequency coaxial switch has a coaxial connector mounted on a housing to provide electrical access to a cavity within the housing, the cavity being small to suppress moding. The coaxial connector is electrically connected to a microstrip conductor on a hybrid circuit board within the cavity, and switching is accomplished by compensated contact striplines which electrically make or break contact with the microstrip conductor.

Abstract: A precision remotely-switched active attenuator comprises a differential amplifier configured with a pair of operational amplifiers that stabilize bias voltages in the differential amplifier and cause more or less signal current to be diverted from an output in accordance with the value of a selectable resistor. Circuit gain can be varied from unity to zero, depending upon the value of the selectable resistor.

Abstract: A method of manufacturing printed circuit boards includes injection molding a polymer component which may include a substrate for a printed circuit, forming circuit runs and circuit pads on the substrate with conductive adhesive, placing circuit components onto the circuit pads and curing the conductive adhesive. The adhesive may be silkscreened onto the polymer substrate. This process obviates the need for the large number of expensive manufacturing steps necessary to produce conventional etched fiberglass printed circuit boards.

Abstract: A circuit for use with a vectorscope to indicate SC/H phase of a composite video signal comprises an oscillator for generating a continuous wave signal at subcarrier frequency and having its phase locked to the horizontal sync point of the video signal, and a switch for connection between the output terminal of the filter of the vectorscope and the second inputs of the demodulators of the vectorscope and for connection also to the oscillator, for alternately connecting the subcarrier burst from the filter of the vectorscope and the sync locked continuous wave from the oscillator to the demodulators.

Abstract: An inverse assembly method for converting binary executable microprocessor code into corresponding assembly language mnemonics provides for the storage of all the possible binary codes and corresponding assembly language mnemonics in a plurality of tables set up in a decision tree form which corresponds to the format of a user document provided by the manufacturer of a target microprocessor. The instructions and data information contained within the executable code acquired from the taret microprocessor are distinguishably tagged prior to being stored in an acquisition memory. The code from the acquisition memory, in binary or hex form, indexes a primary table which contains a plurality of entries containing a binary value which may have a mask portion, each entry containing a plurality of actions having an optional string to be displayed, optional parameter masks and an optional table to call.

Abstract: A control panel supports and positions interchangeable subunit electronic devices and provides a neat and uniform outwardly facing surface. When subunit electronic devices are disconnected from the control panel, cover plates extend and conform to the uniform outwardly facing surface. Hinged support members "lock" in an over center position to rigidly support each cover plate. Electrical connectors protruding from each subunit electronic device "unlock" the hinged support members from the over center position when the subunit electronic device is urged toward the cover plate.

Abstract: An apparatus and method are disclosed which permit selection of colors for display, and easy modification of displayed colors. The apparatus includes a microprocessor, a ROM with a stored program, a RAM with midifiable color data a CRT display for displaying color images, and a keyboard with a cursor-positioning key for identifying a pixel of a displayed color image, and a color menu and H (hue), L (lightness), S (saturation) color modification keys. In response to actuation of one or more of the color modification keys, the microprocessor, under control of the stored program, modifies the stored color data, and uses the modified color data to control the color guns (red, green, blue) of the CRT to modify the color of the identified pixel.

Abstract: A carrier tray for circuit board assemblies. A metal plate is provided (by spot molding) with non-conductive plastic rails. Fastening means are molded into the rails to accommodate variations of circuit board assemblies. Locating posts in combination with resilient locking fingers and circuit board edge receiving slots are formed in the rails to provide a fastening system that is independent of separate fasteners and tools therefor. Lifting levers, also molded into the upper rail, provide for easy removal of the carrier tray from its interconnected position in a card cage.