Abstract: A method and system of converting a wide range of DC input voltages from a DC power source to a substantially lower regulated DC output voltage is disclosed. A pulse width modulated (PWM) signal is generated from an applied DC input voltage to obtain a desired regulated DC output voltage. The PWM signal has a fixed frequency and a variable duty cycle. The PWM signal is filtered to provide a DC output voltage proportional to the amount of time the PWM signal spent in the ON or HIGH state. The duty cycle of the PWM signal is controlled based on an error signal generated by comparing an error voltage level that is proportional to the output voltage to a voltage reference. High voltage protection is provided to the controller during the period the PWM signal is in the OFF or LOW state.

Abstract: An automobile signalling system includes a programmable processing unit or computer mounted in the vehicle near the driver's station. The unit has a key board and a pre-edit screen for displaying an input from the key board. An output from the processing unit is passed to a light emitting diode display unit mounted in the rear window of the vehicle to cause the LED display unit to produce an illuminated representation of the matter appearing on the screen of the processing unit. Output from the processing unit to the display unit is controlled by the braking system of the vehicle so that a message may be displayed on the display unit only when the brakes of the vehicle are activated.

Abstract: A testing device for electrically analyzing electrical failures in high pressure sodium lighting fixtures is disclosed. The testing device is inserted in the lighting fixture after the sodium lamp has been removed and contains three indicator lights. The user of the device compares the condition of the indicator lights with a chart on the label of the device to determine the type of failure. The circuit analyzer device will give distinct indications for a defective lamp, a defective circuit starter board, and a defective ballast and capacitor, thereby allowing the user of the device to make any necessary changes in order to return the lighting fixture to service. A pair of rectifier diodes are installed in a reverse direction so that the pulse to the lamp must be at least 2500 volts in order to break over the diodes PRV rating and to light the appropriate indicating lamps.