Abstract: A brake control unit provides a properly oriented brake control display irrespective of whether the brake control unit is installed in a normal or inverted mode. The brake control unit determines whether a brake control signal is asserted when the brake control unit is connected to a vehicle power supply. If so, the brake control display is inverted. Alternatively, the brake control unit determines orientation by monitoring a position sensitive device. The brake control unit is also capable of determining and displaying the status of a brake load on the brake control display. In addition, the brake control unit is capable of determining and displaying an output voltage of the brake control unit on the brake control display.

Abstract: An electrical charging circuit for applying a controlled charge to a receiving device, such as a battery, and particularly such as a battery carried on a towed vehicle such as a trailer for actuating the trailer brakes during emergency situations such as unexpected disconnection from the towing vehicle, i.e., break-away. In a basic sense, the charging circuit includes a voltage potential-responsive element or component for sensing the charged level of the receiving device coupled to the circuit and enabling or disabling the circuit charging operation, together with a variable-conductance circuit component for producing a generally constant charging voltage output to the receiving device over a wide range of applied voltages but also operable to provide a first amount of current flow to the receiving device at a given applied voltage and temperature but a second a limited amount of current flow when the voltage across the charging circuit is sufficiently large.

Abstract: A vehicle brake controller includes a variable pulse-width modulator operating at a constant frequency and with a variable pulse width to provide control pulses to a MOSFET element which actuates vehicle braking. The controller further includes a visual indicator which displays different colors to representatively indicate the amount of current applied to the brakes, and also to indicate whether an operable connection exists between the electronic controller and the vehicle brakes.

Abstract: An improved electronic controller for electrically actuated vehicle brakes includes a triple sloping integrator for providing a control signal to a pulse with modulator controller. The circuit further includes a protection circuit for protecting electrical devices in the electronic controller from an inadequate electrical ground. Where the electronic controller includes an inertial sensor, the electronic controller includes a current control device for controlling the current flow through the inertial sensor. The electronic controller also includes a device for disabling the inertial sensor.

Abstract: An electronic controller for outputting pulses of current to actuate towed vehicle brakes includes a trigger point inertial sensor for varying the gain thereof. The trigger point inertial sensor includes a switch connected to the controller for switching the gain between two levels. In the preferred embodiment, the inertial sensor and switch comprise a mercury switch supported on a platform which is rotatable to adjust the switching threshold of the inertial sensor, and to adjust for the mounting position of the brake control.

Abstract: A battery charger is disclosed for charging a battery from a vehicle electrical system. The battery charger includes switching devices and a storage element for providing a supply from the vehicle electrical system. The regulator is connected to the switching devices and the storage element for regulating a voltage applied to the battery. The regulated voltage is controlled to have a first value during charging and a second value after the battery is charged.

Abstract: A towed vehicle conversion and isolation circuit is disclosed for coupling dual stop and turn indicator lamps on a towed vehicle to towing vehicles having either dual stop and turn lamps or separate stop and turn lamps. Additionally, the circuit provides a small load to the towing vehicle signaling circuit and isolates the towed vehicle indicator lamps from the towing vehicle signal circuits. Furthermore, the circuit may be coupled to the towed vehicle brake coils to illuminate the towed vehicle lamps responsive to manual actuation of the towed vehicle brake for providing energizing current to the indicator lamps.

Abstract: A field disturbance monitor system which senses changes in a reflected signal caused by animate objects compared to inanimate objects in the same zone. The system employs a microprocessor which controls the system. A transmitter transmits a pulses microwave signal in response to a control signal from the microprocessor. A receiver receives a return signal which represents a reflection of the transmitted signal. A sample and hold circuit senses and holds the magnitude of the pulsed signal. Analog to digital conversion is obtained, whereby a ramp generator generates a ramp voltage which is compared with the magnitude of the received signal by a comparator. The microprocessor measures the time it takes the ramp voltage to rise to the magnitude of the detected signal. The microprocessor continuously computes a recursive short term average and compares this average value with a recursive long-term average. Deviations between the two time periods are the result of a disturbance within the monitoring field.

Abstract: A vehicle brake controller includes a variable pulse-width modulator operating at a constant frequency and with a variable pulse width to provide control pulses to a MOSFET element which actuates vehicle braking. The controller further includes a visual indicator which displays different colors to representatively indicate the amount of current applied to the brakes, and also to indicate whether an operable connection exists between the electronic controller and the vehicle brakes.

Abstract: A freely-flexing cantilever-type inertial sensor is suspended from one end so that its other end may move in response to inertial forces, for example, as a result of braking in a towing vehicle. The pendulum blade is secured to a rigid support structure in a manner whereby the opposite sides of the pendulum, which is preferably of multiple-layer construction and is elastically-deformable, may freely shift longitudinally with respect to one another upon lateral flexure of the pendulum in response to inertial forces. Preferably, this is accomplished by utilizing an adhesive connection directly between the rigid support and the adjacent side of the pendulum, whereby only that layer closest to the support is directly secured to it. The support for the pendulum preferably includes a self-hinge by which the position of the pendulum-supporting portion may be changed with respect to that of a base portion, in order to current for non-verticality in the actual operating environment.

Abstract: The specification relates to electronic controllers for braking systems, such as those used to actuate the brakes on towed vehicles in response to commands from the towing vehicle. The controller is responsive to an inertial sensor and/or manual control, and is completely independent of the towing vehicle brake light circuit. The controller includes a constant frequency variable pulse-width modulator which interacts with the towed vehicle braking system through a power MOSFET switch, which is preferably of N-channel configuration, that comprises the control element for the braking current supplied to the electromagnets that actuate the towed vehicle brakes. The controller advantageously includes a dual-slope integrator which provides a comparatively slow and gradually increasing control voltage to the variable pulse-width modulator, but discharges comparatively quickly to insure fast brake disengagement, in response to the inertial sensor or manual control.

Abstract: A power supply for a gas discharge lamp includes a current regulator for regulating the current supplied to a lamp and current steering means for steering current from the current regulator in alternating directions through an isolation transformer primary winding, the secondary winding of the transformer being connected with a lamp through an arc striking circuit. The frequency of alternating the current through the transformer is controlled as a function of the lamp voltage in order to regulate the volt-second product of the transformer through all portions of a lamp operating cycle including arc striking. This reduces saturation of the transformer and allows a much smaller transformer to be used. In a preferred embodiment, the current regulation and steering functions are performed in a bridge circuit having FET switches in each leg and in which the transformer primary spans the sides of the bridge.

Abstract: A system for producing alternating electromagnetic fields for use in theft detection and surveillance systems, including an arrangement of field-generating inductance coils for disposition on opposite sides of a passage to be monitored by the electromagnetic field produced by such coils. In a preferred such arrangement, upper and lower coils are used on each side of the passage and such coils are mutually distinct from one another and separately energizeable so as to generate separate components of a resulting composite electromagnetic field. The upper and lower coils in each such set are preferably disposed in coplanar alignment with one another but have at least portions of one coil overlapping portions of the other, so as to enhance uniformity in the resulting electromagnetic field. The array of separately-energizeable coils provides for resultant flux vector variation in the magnetic field along three mutually orthogonal axes as a function of coil drive excitation phase variation.

Abstract: A voltage-agile, controlled output, regenerative-feedback power supply control circuit in which a power source is switched by a pair of controlled switch elements so as to supply a selective amount of output power to a load while also selectively completing a regenerative power feedback path, the switch elements preferably constituting FET switches of which a first is connected between the power source input and the circuit power output point and the second is connected between the circuit power output point and the circuit ground conductor. The gate terminals of the first and second FET switches are connected to receive generally opposite types of control signal representations of the level of circuit output power under load in relation to no-load output power.

Abstract: The specification discloses a digital/analog signal analyzer for an electromagnetic surveillance system. Included is a notch filter having a switched capacitor filter controlled by a phase lock loop for nulling a time-varying driving frequency from the received signal. The analyzer further includes structure for digitizing the received signal and for implementing a recursive filter to enhance digital feature extraction. The recursive filter in turn includes structure for delaying a read address for subsequent use as a write address to facilitate the rapid updating of data in memory. Also included is a digital-to-analog converter assembly having a pair of piggy-backed digital-to-analog converters to produce an analog signal dependent upon both a mantissa and an exponent of a digital number in scientific notation.

Abstract: Methods and apparatus for producing alternating electromagnetic fields for use in theft detection and surveillance systems include individual series-type electrical drive circuits for separately energizing each of the field-generating coil windings with maximum efficiency and control, and transformer-type coupling between the different field-generating coil drive circuits to effect balanced and equalized current flow in the different coil windings and thereby enhance both drive efficiency and field uniformity. Additionally, a current-sense winding provides for monitoring of field coil current flow, and for feedback control of the magnitude and/or frequency of the coil excitation drive. In a preferred embodiment, the fields are generated by at least two coils on each opposite side of the field, and the coils are separately energized through separate but commonly-coupled drive circuits.

Abstract: Improvements in theft-detection or surveillance systems of the type in which an alternating electromagnetic field is established across a doorway or other portal and is monitored to detect the presence within the field of a marker or tag member comprising a small strip of permalloy or like material of high permeability hidden or otherwise carried on merchandise or other articles and objects to thereby "mark" such merchandise or objects, i.e., to make them readily detectable even though hidden from view. More particularly regarded, the improvements in accordance herewith reside in signal-processing electronic circuitry which increases detection sensitivity and accuracy while at the same time reducing erroneous detection results.

Abstract: In an electromagnetic passage surveillance system, first and second receiver means are employed in mutually-spaced locations across a guarded portal to detect perturbations in an electromagnetic field extending across the portal, resulting from presence within the field of a high-permeability, low-coercivity marker. From the outputs of such receivers a sum signal and a difference signal are produced, and the high-order harmonics of the sum signal are emphasized to produce a first analysis signal while the low-order harmonics of the difference signal are emphasized to produce a second analysis signal. The ratio of the first analysis signal to the second, and thus the ratio of high-order to low-order harmonics, is used in logic and processing circuitry to dynamically vary the detection threshold by which the presence of a marker is determined.