Abstract: The conversion circuit adapts a legacy radio to play digital broadcasts using a sensing circuit coupled to a control device of the legacy radio to produce a control device position signal. A processor detects changes in this position signal and interprets a pattern of predetermined changes in position signals to generate at least digital radio broadcast scan command. The conversion circuit also includes a digital radio receiver that performs a scan operation in response to the scan command and supplies the processor with a channel list of detected digital stations. The processor associates each of the detected digital stations to a different positional setting of the control device. The processor also interprets different positional settings of the control device as a content selection commands, which it uses to cause the receiver to select a particular content component for playback through an audio amplifier.

Abstract: The conversion circuit adapts a legacy radio to play digital broadcasts using a sensing circuit coupled to a control device of the legacy radio to produce a control device position signal. A processor detects changes in this position signal and interprets a pattern of predetermined changes in position signals to generate at least digital radio broadcast scan command. The conversion circuit also includes a digital radio receiver that performs a scan operation in response to the scan command and supplies the processor with a channel list of detected digital stations. The processor associates each of the detected digital stations to a different positional setting of the control device. The processor also interprets different positional settings of the control device as a content selection commands, which it uses to cause the receiver to select a particular content component for playback through an audio amplifier.

Abstract: Galvanic corrosion of the fuel sender immersed in the corrosive fuel mixture is minimized by supplying the sender with current that periodically switches polarity. The switching rate is selected to prevent or greatly minimize irreversible oxidation buildup. The vehicle body computer responds to current flow through the sender without regard to the alternating polarity drive signal. The switched polarity sender module can thus be employed without necessitating modification of the sender or body computer components.

Abstract: The motor drive circuit has an instrumentation amplifier with a programmable gain set by selectively blowing fuses during initial circuit calibration. The quasi-sawtooth waveform of a relaxation oscillator is compared with the amplified and conditioned signal produced by a pressure responsive Wheatstone bridge circuit. The result of this comparison is a drive signal which controls the pump motor speed. Radio frequency interference is minimized by storing the motor drive current in a capacitor located near the motor. Further interference is minimized by a reactive matching circuit which combines with the motor impedance to result in a purely resistive load.

Abstract: The circuit senses abrupt change in motion of an electromotively-driven part such as the onset of valve seating in a solenoid-operated valve. A constant current source supplies power to the solenoid coil and a pulse detector circuit monitors the voltage across the coil and determines the time rate of change of that voltage. A change in the algebraic sign of the time rate of change in voltage indicates that valve seating has occurred.

Abstract: The power door lock interlock circuit senses the presence of an ignition key in the ignition and also senses when a door is open. When these conditions are met, the power door lock is placed in an interlock condition whereby pressing the power door lock button causes the horn to sound instead of locking the doors. The circuit is thus useful in preventing the driver from accidentally leaving the ignition key in the ignition and accidentally locking all doors. All doors may be unlocked in the usual fashion and all doors may be locked in the usual fashion provided the interlock condition has not been met.

Abstract: The airflow sensor uses a flow sensing bridge having a thermal element which senses airflow as a function of electrical energy applied to the bridge. Energy is applied to the bridge to maintain the thermal element at a constant temperature and constant resistance. A differential amplifier monitors the balanced and unbalanced state of the bridge and controls the application of energy to the bridge to maintain a balanced state. A microcomputer with analog to digital converter senses the level of energy applied to the bridge and converts this energy level to a digital signal indicative of airflow. The raw digital signal is corrected using calibration lookup tables and thermal compensation correction tables in the microcomputer memory circuits. The microcomputer outputs a variable frequency signal indicative of the measured mass airflow. In the alternative to the differential amplifier, the bridge may be balanced using the microcomputer in a sample and hold voltage to current converter configuration.

Abstract: The power door lock interlock circuit senses the presence of an ignition key in the ignition and also senses when a door is open. When these conditions are met, the power door lock is placed in an interlock condition whereby pressing the power door lock button causes the horn to sound instead of locking the doors. The circuit is thus useful in preventing the driver from accidentally leaving the ignition key in the ignition and accidentally locking all doors. All doors may be unlocked in the usual fashion and all doors may be locked in the usual fashion provided the interlock condition has not been met.

Abstract: The programmable telephone screening device routes an incoming call to a selected telephone device, depending on preestablished device priorities and upon access codes dialed by the caller. The device provides call hold, call forwarding and automatic dialing and is capable of testing the telephone utility network to determine DTMF and pulse dialing compatability. The device generates ringer signals for directly energizing the ringer circuits of standard telephone devices.