Abstract: An electronic disconnect circuit protects an electronic device, such as a radio, installed in a motor vehicle from overvoltage condition in which the normal internal protection is inadequate. A normally closed relay includes 2 sets of terminals connected in the ground conductor and in the voltage conductor of the power cable connected to the electronic device. The relay coil is connected through a diode which becomes conductive if the voltage in the ground conductor rises above the voltage in the other conductor, thus protecting the radio or similar electronic device from a reversal of polarity as would occur when a battery charger or similar device is improperly connected to the vehicle. A switching transistor responds to an over voltage condition to turn on the relay coil when an over voltage condition occurs, such as during a high voltage jump start or a high voltage transient condition.

Abstract: An audio-visual system for a motor vehicle includes multiple viewing/listening stations, one station for each passenger. Each station includes a video monitor mounted in the back of the seat immediately in front of the user and includes an audio headphone terminal in a control panel adjacent each viewing station. The control panel includes a multiple position switch, which is connected to a distribution box for switching between multiple program sources for transmission to each viewing station. Accordingly, the user at each viewing station can independently switch between the program sources.