Vdo Adolf Schindling Ag

Vdo Aloft Schindling Ag

Axel Schafer

Klaus Rathmann

A system for the central locking of several closure points of an automotive vehicle with a remotely controlled setting member at each closure point has a central control circuit, as well as activating switches. Each switch has a neutral central position between 'closed' and 'open' positions at one or more closure points, by which the control circuit can be controlled for movement of all setting members in the same direction. A switch sequence of the invention provides for individual opening of a closure point by a process wherein the actuating switch must be brought into the 'closed' position and then immediately into the 'open' position.

Central locking device

A circuit arrangement for controlling a rotary-magnet measuring instrument (6) by an input voltage via a controlled source of current has a first amplifier (difference amplifier 1) with a first negative-feedback resistor (R.sub.2) and a first input resistor (R.sub.1). In order to linearize the approximately S-shaped characteristic curve of the rotary-magnet measuring instrument (6), the controlled source of current is developed with a characteristic curve which is defined as consisting of three straight line segments of differing slope. For this, a second amplifier (difference amplifier 8), controlled as a function of the input voltage and a semiconductor path controlled by it (2nd npn-transistor 12) which lies in series with the first input resistor (R.sub.1) are provided. One input (10) of the second amplifier is connected to a constant voltage divider (divider resistors R.sub.3, R.sub.5) and via a second negative-feedback resistor (R.sub.4), to the controlled semiconductor path and the first input resistor (at point Y). The resistances of the second negative feedback resistor (R.sub.4) and of the constant voltage divider (divider resistors R.sub.3 , R.sub.5) are small as compared the resistance of the first input resistor (R.sub.1).

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Bad Soden, Germany

Axel Schafer