Abstract: A circuit for a power amplifier includes a main amplifier stage having an operational amplifier (110), a buffer NPN transistor (126) and an NPN transistor (127) connected in a totem pole configuration, and a buffer PNP transistor (133) and a PNP transistor connected in a totem pole configuration. The transistors regulate the voltage to the components directly connected to the operational amplifier (110 ). A sampling resistor (137) located between a speaker (140) and an output of the power amplifier measures the current. The sampling resistor (137) is inside a negative feedback loop so that an output resistance will be near zero. A protection circuit includes a high common mode rejection difference amplifier that level shifts the sampling resistor voltage to a ground reference voltage. A precision rectifier full wave rectifies the current signal so that the current signal can he compared to a maximum current.

Abstract: An instrument measures the LED junction temperature directly by taking advantage of the linear relationship between the forward current driven through the LED, the forward drop of the LED, and the junction temperature to determine the LED junction temperature. Calibration is conducted by placing two LEDs from the same family in ambient temperature and passing a small test current through each of the LEDs to obtain the forward drop of the LED at ambient temperature. The LED under test is then placed in an environmentally-controlled chamber where the temperature is raised a known amount above ambient temperature. Known low and high voltage values are associated with the ambient temperature and the environmental chamber temperature, causing the LED under test becomes a calibrated thermometer that can measure its own junction temperature due to the linear relationship between the forward drop and the junction temperature.

Abstract: The development port or Debug port of a microprocessor on an intelligent daughterboard is used for downloading code or configuration information from a motherboard for use in boot-up. In various aspects, the code or configuration information can include information used for configuring a port, other than the development port, and/or for configuring a memory controller, such as for a daughterboard DRAM. Use of the Debug port makes it possible to reduce or eliminate the need for storing boot-up code or configuration information on a daughterboard ROM, or other non-volatile memory, thus reducing cost and space requirements, power consumption and the like.

Abstract: An instrument measures the LED junction temperature directly by taking advantage of the linear relationship between the forward current driven through the LED, the forward drop of the LED, and the junction temperature to determine the LED junction temperature. Calibration is conducted by placing two LEDs from the same family in ambient temperature and passing a small test current through each of the LEDs to obtain the forward drop of the LED at ambient temperature. The LED under test is then placed in an environmentally-controlled chamber where the temperature is raised a known amount above ambient temperature. Known low and high voltage values are associated with the ambient temperature and the environmental chamber temperature, causing the LED under test becomes a calibrated thermometer that can measure its own junction temperature due to the linear relationship between the forward drop and the junction temperature.

Abstract: An energy balanced weld controller includes a mid frequency direct current power supply and a weld switch that turns the current to weld caps on or off. The weld caps are used to produce a weld on workpieces. The tip voltage and the weld current are multiplied to generate a voltage which is converted to a frequency. The output represents the amount of energy provided to the weld and is provided to a frequency counter that counts the amount of energy delivered to the weld. A magnitude comparator compares the energy delivered to the weld to a target energy. When the energy delivered to the weld equals the target energy, the magnitude comparator sends a high signal to the weld switch to terminate the weld.

Abstract: A light emitting diode (LED)has an integrated heat sink structure for removing heat from an LED junction and for dissipating heat from the junction to the ambient air. The anode and the cathode both either act as or are coupled to a thermally conductive material which acts as the heat sink. In one embodiment, the heat sink forms a mounting configuration that allows air to circulate around multiple surfaces to maximize heat dissipation. As a result, the LED junction temperature remains low, allowing the LED to by driven with higher currents and generate a higher light output without adverse temperature-related effects.

Abstract: An instrument measures the LED junction temperature directly by taking advantage of the linear relationship between the forward current driven through the LED, the forward drop of the LED, and the junction temperature to determine the LED junction temperature.

Abstract: A light emitting diode (LED) designed to be used in conjunction with a heat sink includes an anode portion and a cathode portion formed from a thermally conductive material. The anode and cathode portions have a relatively large surface area to allow efficient heat dissipation. The cathode portion has a reflector cup formed thereon for supporting an LED chip. The LED structure allows the LED junction temperature to remain low, even as the LED chip is driven with higher currents, thereby allowing the LED to generate a higher light output without adverse temperature-related effects.

Abstract: A light emitting diode (LED) has an integrated heat sink structure for removing heat from an LED junction and for dissipating heat from the junction to the ambient air. The anode and the cathode both either act as or are coupled to a thermally conductive material which acts as the heat sink. In one embodiment, the heat sink forms a mounting configuration that allows air to circulate around multiple surfaces to maximize heat dissipation. As a result, the LED junction temperature remains low, allowing the LED to by driven with higher currents and generate a higher light output without adverse temperature-related effects.

Abstract: A magnetic sensor for a magnetic anomaly detector includes a bobbin made from a layered printed circuit board material. A plurality of non-ferrous leads are attached to the bobbin for providing external connection to the sensor. A metal strip is attached to the bobbin. The strip is made from a material having a high permeability. First and second coils are wound around the bobbin and over the metal strip. The bobbin interconnects the first and second coils.

Abstract: A variable resistor/bar graph driver multiplexer uses a resistor network for obtaining a variable resistance and a constant current source. The resistor network contains a plurality of switches such that each switch corresponds with a particular resistor when depressed, thereby providing one of a plurality of output voltages. The output voltage is received by a receiver containing a bar graph driver circuit and a plurality of PNP drivers and relay coils corresponding to the switches at the transmitter. The relay coils will turn on depending on the switch pushed at the transmitter. This multiplexer circuit allows a large amount of switch position information and multiple to be transmitted over only two signal lines rather than the large number of lines used in conventional multiplexers. The multiplexer circuit can also be implemented using analog-to-digital converters and digital-to-analog converters at the receiver.

Abstract: A magnetic anomaly detector for detecting the presence of ferrous metal objects such as firearms, knives, or other weapons. The detector contains a square wave generator, a sensor for sensing ferrous metal objects, a sensor amplifier, a main amplifier, and a display. When a ferrous metal object is detected by the sensor, the resultant anomaly in the magnetic field causes portions of a pulse train being input to the sensor amplifier extend past a preset threshold, causing an average input value of an integrator to change. The integrator then forces the average input value of the waveform to zero over an extended period of time to compensate for the changes in the magnetic field. The value at the integrator input represents the magnetic anomaly. The anomaly is also visually displayed in an LED bar graph display for easy detection of weapons by the operator.

Abstract: A fault tolerant communication system for transmitting a serial data signal through multiple wires regardless of whether one of the wires is open circuited, shorted to ground, shorted to a positive power supply. The system includes at least two communication lines. Each communication line is provided with identical data signals. The outputs of the communication line are adapted such that the active levels of each of the respective data signals appear within a predetermined voltage range. At least two detecting means are coupled to the communication lines. Each of the detecting means transmits one of the respective data signals only if the active levels of at least one of the respective data signals is within the predetermined voltage range. A fault is detected when the active level of any of the data signals is outside the predetermined voltage range. Combining means are coupled to each of the detecting means for combining the respective data signals from the detecting means into a single data signal.

Abstract: Provided is a magnetomoter apparatus for measuring low-level magnetic fields. The magnetometer utilizes a coil-pair wound on cores of a high permeability material. These coils are driven to magnetic saturation by an energizing circuit, and develop a uniquely shaped distortion spike in their back emf having an amplitude which is directly related to the ambient magnetic field. The resulting back emf of the coils can be compared and processed to generate a measurement of the ambient magnetic field.

Abstract: Provided is a magnetomoter apparatus for measuring low-level magnetic fields. The magnetometer utilizes a coil pair wound on cores of a high permeability material. These coils are driven to magnetic saturation by an energizing circuit, and develop a uniquely shaped distortion spike in their back emf having an amplitude which is directly related to the ambient magnetic field. The resulting back emf of the coils can be compared and processed to generate a measurement of the ambient magnetic field.

Abstract: This invention provides an automatic current interruption to protect the audio power amplifier circuitry when current conditions above the capacity of the power amplifier are encountered. The circuit monitors the current supplied to the power amplifier and utilizes a transistor to interrupt power amplifier output. Power output is latched in its interrupted state until reset and is capable of quickly and effectively shutting down power supply output.

Abstract: A method and circuit for supplying power from a constantly available power source (20) to an audio power amplifier (14) for a speaker (12) utilizing input leads (16,18) having an audio signal. A pre-amplifier (24) is used for amplifying the audio signal having a difference in potential between the input leads (16,18). A switch (58) powers the audio power amplifier (14) and pre-amplifier (24) from the power source (20) in response to a control signal. The method and circuit is characterized by sensing (26) the existence of a diminished audio signal by determining a greater difference than the predetermined difference between the input leads (16,18) to produce the control signal which operates a relay driver transistor (62) which, in turn, operates a relay switch (66) to supply power to the pre-amplifier (24) and power amplifier (14).

Abstract: An electrical timing circuit for controlling the activation and deactivation of an electrical load by setting a predetermined time period for which the load will be on and for providing one or more short warning periods wherein the load is deactivated prior to the expiration of the predetermined time period. The invention may be used as a switch for a light whereby the light may be actuated to remain on for an hour, but just prior to the expiration of hour period the light will momentarily go off for one or more warning periods prior to the light being turned completely off so that the switch may be reactuated to start another timing period. Momentary switches (12) control a set-reset circuit (16) which sends a signal to a NAND gate (18). A timing circuit (20) is responsive to the momentary switches (12) to provide a plurality of time spaced-signals.

Abstract: An amplifier circuit for a speaker 12. The circuit includes an operational amplifier 16 connected to a supply rail 24 and a supply rail 26 through a regulator 28 and a regulator 30. The circuit is characterized by a P channel MOS-FET 32 having a source 34 connected to the rail 24 and a drain 36 connected to the speaker 12 and a gate 38, and an N channel MOS-FET 40 having a source 42 connected to the rail 26 and a drain 44 connected to the speaker 12 and a gate 46. A NPN stage 48 is responsive to the output 56 of the amplifier 16 for establishing a voltage differential between the gate 38 of the MOS-FET 32 and the rail 24 to drive the MOS-FET 32 into conduction. A PNP stage 50 is responsive to the output 56 of the amplifier 16 for establishing a voltage differential between the gate 46 of the MOS-FET 40 and the rail 26 to drive the MOS-FET 40 into conduction. The stages 48, 50 are connected to ground 52.

Abstract: An airflow sensor for a constant temperature anemometer comprises a copper foil resistor mounted on a polyimide foil which is supported in the airstream to be measured. The support preferably is a flat frame having an aperture over which the foil sensor is mounted so that the airstream can strike the sensor on both sides of the film. Airflow directors mounted upstream of the sensor are placed at an angle to direct the airstream toward each side of the film at a definite angle to obtain a positive cooling effect of the film by the airstream and consistent airflow. The sensor assembly is mounted in a duct with the plane of the sensor along the longitudinal axis of the duct for measurement of the flow through the duct. Another embodiment has a diamond shaped body mounted in an airflow such that a straight airflow impinges upon two forward sides of the body at a specific angle.