Abstract: A power regulation device and method for a model railway system is provided. The device comprises inputs that connect to a supply of a digital command control (DCC) waveform and to a track section to be powered by the DCC waveform. The device comprises a current measuring circuit that measures current flow associated with the DCC waveform supplied at the inputs. A switch is connected between the inputs and outputs that are in turn connected to respective rails of the track section. A controller is provided that analyzes a current measurement signal produced by the current measuring circuit and controls the switch to disconnect supply of the DCC waveform to the outputs when a true over-current condition is detected. The device may also comprise an auto-reversing function to accommodate reverse loop track sections.

Abstract: A power regulation device and method for a model railway system is provided. The device comprises inputs that connect to a supply of a digital command control (DCC) waveform and to a track section to be powered by the DCC waveform. The device comprises a current measuring circuit that measures current flow associated with the DCC waveform supplied at the inputs. A switch is connected between the inputs and outputs that are in turn connected to respective rails of the track section. A controller is provided that analyzes a current measurement signal produced by the current measuring circuit and controls the switch to disconnect supply of the DCC waveform to the outputs when a true over-current condition is detected. The device may also comprise an auto-reversing function to accommodate reverse loop track sections.

Abstract: An improved coupler for model trains is disclosed that provides for remote control vertical movement of a moveable coupler box. The improved coupler allows cars of a train to be coupled or uncoupled at any location along the track. An NMRA compliant DCC control system located on board a linkable car is used to receive the remote control signal, and a circuit, motor, and linkage are provided to translate function commands into up and down vertical movements of the moveable coupler box. Addressing is provided to control which car of the train is to be decoupled.

Abstract: A method and apparatus determines a quantity of liquid in a tank when at least one liquid sensor is inoperative. In a first embodiment, a plurality of tables are stored in memory which are grouped by identities of the possible inoperative sensor or sensors. One group of tables is selected based on the identified inoperative sensor or sensors. Then, that one group of tables is accessed, and the quantity of liquid in the tank is calculated based on the readings of the operative sensors. In a second embodiment, a first plurality of tables stores quantity readings for each sensor as if all sensors are operable. A second plurality of tables includes one table for each possible configuration of inoperative sensor or sensors. When the inoperative sensor or sensors are identified, one particular table in the second plurality is accessed and a quantity amount is then added to the liquid quantities determined from the first plurality of tables to provide a total liquid quantity in the tank.

Abstract: Apparatus and method for determining capacitive and resistive values of an electrical component, such as a fuel level determining probe, includes a waveform generator for subjecting the probe to a time-varying waveform that includes a linearly varying ramp portion and a fixed, constant portion. A selectively controlled sample and hold circuit senses the voltage potential of the probe in response to a zero-crossing detector during the linearly varying ramp portion of the waveform to provide information indicative of the capacitive value and again senses the voltage potential at selected time thereafter during the fixed portion of the waveform to provide resistive value information. The output of the sample and hold is provided to an analog-to-digital converter which provided digital information to a stored-program controlled processor which provides the desired output information.

Abstract: A liquid level sensor system well suited for sensing the level of fuel in aircraft fuel tanks includes a plurality of capacitive sensors which provide an output capacitance that is a function of the fraction of the sensor wetted by the fuel. A plurality of sensors are positioned in the liquid-containing tank with each sensor having a first and at least a second probe-specific liquid-quantity profile corresponding to a first and at least a second attitude of the tank. The capacitance of the sensors are determined as function of the length of the respective sensor wetted by the liquid. A memory is provided with a first and second sets of address locations containing liquid-quantity profile information for the sensors for their respective first and second attitudes. The memory is addressed by determining an address offset as a function of the attitude of the system, the relative location of the profile information for the sensor, and the fraction of the sensor wetted by the liquid.

Abstract: Apparatus for the ratiometric measurement of a quantity of liquid in a tank includes first and second capacitors disposed in a tank and responsive to an AC excitation signal. The output signal from the first capacitor corresponds to the quantity of liquid in a tank, while the output signal of the second capacitor corresponds to an empty tank condition. First and second rectifiers are respectively coupled to the first and second capacitors. Preferably, the rectifiers are each a diode pair of opposite polarity diodes. The output signal from each rectifier is thus a current signal. A first current-to-voltage converter is coupled to both the first and second rectifiers and provides a first voltage signal corresponding to the first and second rectified signals. A second current-to-voltage converter is coupled to the second rectifier and provides a second voltage signal corresponding to the second rectified signal.

Abstract: Apparatus for use with a densitometer having a probe with an output and a probe driver for driving the probe includes a loop circuit coupled between the probe output and the probe driver. An amplifying circuit is coupled in the loop circuit to amplify the signal provided by the probe. A phase/gain control device is also coupled in the loop circuit between the amplifying device and the probe driver. The phase/gain control device controls the loop circuit to provide a loop gain of at least one and a substantially zero degree phase shift between the probe driver and the probe output signal. The amplifying device includes an op-amp which is preferably coupled to a shielded cable carrying the probe output signal. The shield conductor and one input of the op-amp are held at ground potential, and the op-amp acts to hold the center conductor at ground potential also. With the center conductor held at ground potential, the output signal from the probe varies with current, not voltage.

Abstract: A system for independently determining the capacitance and resistance of a capacitive sensor, in which the sensor and a reference capacitor are sequentially energized from two alternating voltage sources of different frequencies, and average sensor and reference capacitor current valves at the two frequencies are measured and supplied to a computer which periodically calculates the sensor capacitance and resistance.

Abstract: A capacitive probe detection system is described which incorporates a synchronous switching system to switch the current flow through a capacitive probe to a signal integrating circuit only during the whole of every positive half cycle of the current flow attributable to the capacitive component of the probe. In this way that current due to the resistive component of the probe and to spurious noise pulses is eliminated by the integrator when performing its integrating action.

Abstract: A circuit for detecting failure of a segment in a digital display which includes a comparator connected to the energizing circuit for the display segments so that when a segment fails and is addressed, the comparator output is changed to provide a blanking signal which is fed by a circuit to the blanking input of the display driver for blanking the display. The energizing circuit for the display includes lamp test means, which, after display blanking, is actuated to energize all of the segments thereby permitting identification of the failed segment. Release of the lamp test means activates a timer circuit for providing an override signal for overriding the blanking signal to return the display to normal operation for a predetermined period of time following which the display will be blanked again when the failed segment is again addressed.

Abstract: A full height compensation circuit for a capacitive type probe of the type used to measure the mass of fuel in a tank which includes a probe capacitor for immersion in the fuel connected to a source of power for supplying current to the probe capacitor, the probe capacitor current being summed with a current corresponding to the capacitance of the fuel tank in the empty state to provide an output voltage, the output voltage being positively integrated to a predetermined value as determined by the number of pulses counted by a counter, following which the counter is actuated to count down the number of pulses required to return the integrated output voltage to zero, and the number of pulses counted down providing a digital number output proportional to the mass of fuel sensed by the probe capacitor.

Abstract: A capacitive proximity sensor for use in hostile environments comprises a ceramic substrate, and two conductive regions formed on the substrate and having opposed edges defining a narrow gap therebetween. The gap configuration is such as to maximize the fringing of electric flux lines outwards from the substrate when one conductive region is energized from a high frequency source. The other conductive region is connected to remotely located signal conditioner operative to maintain said other region at virtual ground and thereby eliminate signal error due to cabling capacitances. On approach of a flux-shielding body to the sensor, the sensor output current to the signal conditioner will decrease as a function of the proximity of the body. The sensor can be used as a simple proximity sensor or incorporated in a shaft torque measurement system operative down to zero r.p.m.

Abstract: A liquid-level gauging system comprises a capacitive probe arranged in a liquid storage tank and electrically connected into timing circuitry of a pulse generator to render the period of the pulse output produced by the generator directly proportional to the probe capacitance and thus proportional to the level of liquid in the tank. The generator pulse output is used to gate a counter receiving pulses from an oscillator whereby, for each cycle of the generator output, an accumulated count is produced in the counter which is proportional to the cycle period. This count is a proportionate measure of the liquid level. The count can be used as an address code for a read-only memory such that the memory output is the number stored in the memory at the address represented by the count value. Suitable programming of the memory can thus give any desired relation between count value and memory output and therefore any desired relation between memory output and tank liquid level.