Abstract: An adaptive stepper for adjusting welding heat boost to compensate for deterioration (flattening) of the electrode tips of a welder. Heat boost is provided to the welder as a function of expulsion rather than by a series of linear step profiles specified by a weld engineer. An operator sets up an adaptive schedule based upon an expected resistance difference between consecutive half-cycles considered to be "normal." If differences equal to or less than the normal level are detected during a group of welds, the heat boost will be incremented by 1% after a preprogrammed number of welds have been made. If differences greater than normal are detected, indicating expulsion, the boost will be decremented immediately by 1% between increases, if decrements are allowed at the time.

Abstract: The present invention is directed to a programmable logical controller (PLC) system incorporating a universal input controller card, a universal output controller card, and a symmetrical current mirror fuse blown detector circuit. The universal input controller card is capable of tracking input voltages from 12 to 240 volts, AC or DC. The universal output controller card is capable of outputting output voltages ranging from 12 to 120 volts, AC or DC with no significant leakage current and no load resistors. The current mirror fuse blown detector circuit detects blown fuses in each output channel of the output controller card.

Abstract: A method and system is disclosed for determining the location of a member of a class of individual transmitter-receiver units distributed throughout a defined facility. A central station establishes a two-way communication channel with one or more relay stations and sends a coded message identifying a particular individual unit over the communication channel. The relay stations respond to the message by sending out wake-up signals and radiant energy inquiry signals. The individual unit identified in the inquiry signal responds with a radiant energy acknowledgment signal. Embodiments of the invention disclose the use of infrared energy or ultrasonic energy for the radiant energy. Ultrasonic signals are sent on a plurality of frequencies. The relay stations send identification signals to the central station which identify the sending relay station and indicate whether an acknowledgment signal was received.

Abstract: A synchro power amplifier and control circuit for an inductive load has a plurality of synchro leg amplifiers connected to the load. Each amplifier has an interstage transformer for deriving samples of current drawn by the load. A multiplicity of capacitors are respectively connectable in parallel with the (load) upstream of the amplifiers by switches in a circuit 10 responsive to the voltage/current phase angle of the power driving the load, to compensate for the inductance of the load.

Abstract: A voltage converter of the transformer type which incorporates at least one switching transistor coupled to control the application of current to the transformer primary and circuitry for switching the transistor off in response to the current drawn through the primary winding and the level of the input line voltage. Overcurrent shutdown may thus be tailored to approximate constant power dissipation within the voltage converter.

Abstract: A self-starting transformer-coupled FET multivibrator is constructed to avoid net dc flow in the primary winding of its transformer, driven push-pull by the multivibrator FET's.

Abstract: In a voltage conversion circuit, comprising a source of input DC voltage, an input voltage switching circuit and a transformer having a primary winding coupled in series with the switching circuit and input DC voltage for periodically receiving DC voltage thereat and having a secondary winding connected to a DC output circuit for producing a DC output voltage of a given polarity, the transformer primary normally undesirably produces a switching circuit damaging voltage spike of a polarity opposite the given polarity upon the voltage being removed from the transformer primary by the switching circuit. A voltage suppression circuit is responsive to the voltage polarity reversal in the transformer primary, which occurs when the input voltage is removed therefrom for storing the energy which would otherwise produce the voltage spike.

Abstract: A voltage conversion circuit includes a transformer having a primary winding and a secondary winding with an output terminal. The primary winding is coupled in series with a switching circuit across a source of DC potential. The switching circuit periodically interrupts the DC potential to the primary winding and upon the interruption the primary winding undesirably produces a switching circuit damaging voltage spike. A voltage suppression circuit is responsive to the voltage polarity reversal in the transformer primary, which occurs when the input voltage is interrupted thereto for transferring the energy, which would otherwise produce the voltage spike, to the converter output terminal to add energy thereto. When the switching circuit is non-operational no voltage reversals are present in the transformer and no voltage is therefore passed to the output terminal.

Abstract: A voltage converter of the transformer type which incorporates at least one switching transistor coupled to control the application of current to the transformer primary and circuitry for switching the transistor on and off to control the current through the primary winding. When the output of the converter is shorted, the switching rate undesirably increases causing potential damage to the converter. A frequency detecting circuit detects the increase in switching frequency and acts to reduce the input voltage to the converter to prevent damage thereto.

Abstract: An airborne weather radar system displays on a display screen a weather map in the form of a matrix of spots of intensity with N possible intensity levels ranging from a lowest level to a highest level where N>2 and where the intensity levels correspond to respective data signals provided by the radar system. The intensity control on the weather radar system is operator controllable to cause data signals corresponding to all intensity levels except the lowest to be converted to signals corresponding to the highest level. Therefore, only the highest and lowest intensity levels are displayed.

Abstract: A power supply which incorporates a feedback network for maintaining an output parameter at a nominal value, includes apparatus, which, upon a change in an environmental parameter provides a signal to the feedback network to alter substantially the output parameter from its nominal value. Such a power supply is useful in a cathode ray tube type display system subject to damaging voltage breakdowns at high altitudes.