Abstract: A parametric test circuit adapted for testing a device in two alternate modes of operation. In one mode, the circuit forces a voltage on the device under test and measures the current drawn. In the alternate mode, the circuit forces voltage on the device under test and measures the voltage. The same circuit components including a difference amplifier are used in both modes of operation, and they are merely reconfigured by a plurality of switches. Further, a plurality of range resistor sections are used, and the nonselected sections are prevented from interfering with the selected section by zero-biasing anti-parallel diode pairs in series with the nonselected range resistors.

Abstract: A sealed gas surface burner having a ring portion that sits on the main top around the periphery of the main top aperture through which the burner extends. The ring portion forms a substantially liquid tight seal with the main top, and has a raised shoulder to prevent liquid on the main top from running down through the burner aperture in the main top. A burner body is supported by the ring portion at spaced intervals to provide passageways from underneath the main top. A cap is supported by the burner body thereby forming a chamber which receives a mixture of gaseous fuel and primary combustion air. The mixture issues from ports in the side wall of the burner body where it is ignited to produce a cooking flame. Secondary combustion air is drawn from underneath the main top through the passageways in the burner to support combustion of the flame.

Abstract: A method and apparatus for discriminating and collecting coins wherein an inserted coin is received in a notch of a rotary disk. Upon sensing the insertion of a coin into the notch, a motor rotates the disk through a predetermined arc to a predetermined angular orientation where a decision is made whether to accept or reject the coin based on coin characteristics such as the sensed diameter of the coin and metal content. If the coin is accepted, the disk is rotated to an angular orientation where the coin falls from the notch into a coin collection box. However, if the coin is rejected, the disk is rotated in the opposite direction to an angular orientation where the coin falls into a coin return chute. Sensors are also provided to sense the presence of the coin in the notch on the way back to the initial angular orientation. If the coin failed to fall out for any reason, another attempt is made to collect the coin.

Abstract: A refrigerator door handle and a method of attaching the handle to a door panel. A door handle retainer strip includes an elongated channel having a shoulder opposite a laterally extending longitudinal groove. After the retainer strip is screwed to the door panel, a rail on the back of the handle is inserted into the channel. The rail has a laterally extending tongue that is received in sliding engagement in the groove as the handle is moved laterally. The handle is then secured or locked in that position within the channel of the retainer strip by driving screws between the shoulder and the rail at the ends of the handle.

Abstract: A high speed clock recovery system that provides a precise 90.degree. phase shift at the incoming NRZ data rate by using a series of differential inverters and controlling their delays in accordance with the corresponding delays of differential inverters of a ring oscillator that is part of a phase-locked loop. More particularly, the incoming NRZ data and the phase shifted data are fed to an exclusive OR that provides an output signal including a frequency component of the originating clock of the NRZ data. The phase-locked loop further includes a phase detector which is responsive to the output of the exclusive OR and the ring oscillator. Thus, once the loop locks, the ring oscillator is synchronized to the frequency of the originating clock for the NRZ data. By slaving the differential inverters of the phase shifter and the ring oscillator to the same delays, the phase shifter provides a dynamically adjusted delay of precisely 90.degree. at the originating clock frequency of the incoming NRZ data.

Abstract: A method and apparatus for discriminating coins based on their metal or ferrous content. Coins are transported by a rotary mechanism that stops when a coin is accurately positioned with respect to an adjacent metal sensor. The metal sensor is then activated to provide a measurement signal of the coin in the repeatable stationary position. A plurality of measurements may preferably be taken and averaged to increase the accuracy.

Abstract: A subranging analog-to-digital converter wherein, during a first phase, a differential analog input voltage is held by a track and hold circuit and is fed to a low resolution flash ADC to provide the most significant bits (MSBs). During a second or recirculating phase, flash ADC output segments corresponding to the MSBs are fed to respective current switches of a current DAC to produce complementary analog conversion currents that are coupled to the track and hold circuit. In response to the complementary DAC currents, the output stage of the track and hold circuit is used to subtract a voltage corresponding to the MSBs from the input voltage without the use of a separate subtractor. Further, the DAC current switches provide equal currents during the first or MSB phase to deactivate the subtraction function during the first phase.

Abstract: A power divider couples a received signal to a pair of signal channels. The first channel includes a pulse signal processor coupled to the power divider through a band reject filter. The second channel includes a continuous wave signal detector and processor coupled to the power divider through a bandpass filter. The bandpass and band reject filters are responsive to a control signal for tuning the center frequencies of the respective pass band and reject band to a frequency within a predetermined range of frequencies. The continuous wave signal detector and processor determines the frequency of a detected continuous wave signal using the first channel, and tunes, by producing the above-mentioned control signal, the center frequencies of the bandpass and band reject filters to the frequency of the detected continuous wave signal. The band reject filter rejects the continuous wave signal in the first channel.

Abstract: A method and apparatus for spinning and draining an automatic clothes washer after a wash or rinse cycle. After the water is pumped down, the spin drive and drain pump are activated with an on and off schedule of increasing on times, but constant off times. For example, the spin drive and drain pump may be activated for on times of 10, 15, 20, etc. with interleaved off times of 5 seconds. The off times of the drain pump allow suds in the drain pump to be purged, and thereby increase the steady state flow rate of the drain pump.

Abstract: A solderless audio connector plug including a handle, a plug body, and a conductive sheath having fingers flared outwardly with the free ends pointing inwardly. In assembly, the end of a coaxial cable is inserted through a bore in the handle, and then inserted into the sheath. The plug body is then screwed to the handle, and, as the two are drawn together, the sheath is forced into the bore of the handle. The bore tapers downwardly pushing the fingers inwardly to pierce the outer insulation layer of the coaxial cable. Further, a pointed end of a tip rod is aligned within the plug body to make contact with the center conductor of the coaxial cable. In such manner, electrical continuity is established between the outer conductor and the plug body, and also between the center conductor and the tip rod.

Abstract: A moisture content measuring apparatus and method wherein a sensor station produces calibration data corresponding to measurements of light at two different wavelengths reflected from a material, and the calibration data is then transferred to a hand held computer. The moisture content of a sample of the material is measured and input to the hand held computer. The process is repeated after changing the wetness of the material, and the hand held computer creates a table correlating reflection data to moisture content. The table is transferred to the sensor station which then continuously generates signals representing moisture content in response to real time reflection data and the table. The cost effectiveness of the sensor stations readily facilitates the use of a dedicated sensor station at each of a plurality of conveyors carrying different materials to be combined into a composite of predetermined proportions by weight.

Abstract: A pin driver amplifier having a complementary pair of transistors with a pair of resistors coupled between the respective emitters. A node between the resistors is coupled through an output series resistor to an output terminal adapted for connection of a transmission line that conducts driver pulses of predetermined voltage levels and timing to a device under test. A capacitor is tied between the emitters to provide a substantially constant reverse termination impedance for the transmission line thereby reducing reflections. Also, an RC network is coupled between the output terminal and ground to further reduce reflections. The amplifier transistors are driven by respective buffer transistor emitters that are tied together by a capacitor to make the positive and negative going drive capabilities for the amplifier transistors more equal. Further, capacitors are coupled between the amplifier collectors and ground to provide a bypass for parasitic inductance in the supply voltage wires.

Abstract: A digital-to-analog converter switch provides substantially equal propagation delays for both high-to-low and low-to-high transitions of the binary input signal. A ground path transistor and an output transistor are connected to a common node and operated in different states of conduction as determined by the gate voltage on the ground path transistor. A substantially constant current is fed to the node and is either switched through the output transistor or the ground path transistor. In order to compensate for unequal propagation delays in switching the current on and off through the output transistor, additional mimic transistors are provided between the binary input signal and the gate of the ground path transistor. Therefore, transitions in both directions involve one fast and one short propagation delay.

Abstract: Method and apparatus for bending serpentine heat exchanger tubes using a split bend die having a relatively short upper die section with a straight back end. After the tube is bent in conventional manner using a clamp die and a pressure die, the bend die is split along a shaft and rotated through a predetermined angle to position the straight back end substantially parallel to a straight segment of the tube at the output of the bend die. The input segment of the tube is then moved next to the shaft in preparation for rotating above the input segment to raise the output segment above the upper section of the bend die. Such lateral motion reduces the segment spacing required for clearance of the upper section. Other features for reducing the spacing are providing an indentation on the shaft, angling the back end with respect to the sides to provide a minimum length, and truncation an upper portion along the back end.

Abstract: A marine autopilot having a deadband feature to reduce ineffectual rudder movement and unnecessary wear on the rudder and associated drive apparatus. In a first deadband operation, four deadband values are computed based on various parameters in order to provide optimum system performance and circuit redundancy. The deadband values are a function of the maximum allowable heading error, the maximum allowable angular velocity of the vessel, and the vessel speed. A second deadband operation compensates for noise introduced into the autopilot system by the speed sensor, compass, and roll sensor.

Abstract: A fishfinder having a real time or A-scope display with a numerical readout indicating the diameter of the transducer beam on the bottom of the water body. Further, an indicia indicating the position of the boat and downwardly diverging lines corresponding to the transducer beam are overlaid on the display.

Abstract: A transmitter/receiver system is provided wherein a transmitter of such system produces a transmitted signal frequency modulated in accordance with the level of a modulating signal and a receiving antenna has an output thereof coupled to a receiver through a switch means, for coupling or inhibiting signals received by the receiving antenna from passing to the receiver selectively in accordance with the level of the modulating signal.

Abstract: A circuit for increasing the slew rate of linear amplifier circuits. The circuit comprises two NPN and PNP transistor pairs arranged so that when the voltage level difference between the amplifier output and input voltage exceeds the base to emitter voltage of such transistors, the circuit is activated. The circuit provides a current proportional to such voltage difference in order to speed up the charging or discharging of the slew rate determining capacitance.

Abstract: A track and hold circuit for producing an output voltage having a level related to the voltage level of an input voltage fed to the circuit during a track mode and for maintaining the level of the output voltage constant during a hold mode. The circuit includes a current source and a capacitor with the capacitor being charged with the current or discharged selectively in accordance with the level of the input voltage relative to the level of the output voltage to produce at the capacitor the voltage related to the voltage level of the input voltage. Current from the current source is directed away from the capacitor during the hold mode in order to reduce the effect of charge stored during the track mode from slowing the transition from track mode to hold mode operation.

Abstract: A gas surface range having a downdraft ventilation system with automatic shut off during ignition. A relay is activated by current flowing to the spark coil of the electrical igniter, and has contacts connected in series with the blower motor of the downdraft system. Thus, the downdraft system is disabled during attempted ignition, and is automatically enabled at the completion of ignition.