Cerberus Ag

Otto Meier

Andreas Scheidweiler

Felix Huber

Bernhard Durrer

Peter Gruber

A surveillance device, e.g. a fire alarm or an intrusion detector, includes a mount having a connector block, and an insert having a sensor assembly, a printed circuit board with evaluation electronics, and an electrical contact to the connector block. The printed circuit board is a plug-in card with a contact strip. For insertion, with the mount disposed at a horizontal surface, for example, the insert is first moved vertically and then displaced horizontally. In the horizontal displacement, an electrical connection is established between the contact strip and the connector block.

Automatic surveillance device

Control panel for a terminal

Terminal for detecting, signaling and evaluating various hazard

An ionization chamber with two electrodes having a variable spacing and with a radioactive source for the ionization of the electrode gap therebetween includes an adjusting mechanism for the positional adjustment of one of the electrodes relative to the other. The mechanism is such that a spring element presses the adjustable electrode against at least one point of the adjusting mechanism. Several arrangements are disclosed for adjustably mounting a cup-shaped electrode in the housing of the chamber in such a manner that it is readily adjustable and will not undergo spurious readjustment as a result of vibration of shock.

Adjustable ionization chamber

To render an ionization-type sensing element essentially immune to changes in ambient conditions, principally temperature or operating voltage, while still using low-current draining circuits to sense response of the ionization chamber of the sensor, the threshold response level of a field effect transistor (FET) is arranged to have approximately the same temperature response characteristic, within the range of ambient temperature considered, as the ionization cell so that the overall circuit or system combination of the cell and FET amplifier will have a response which is essentially independent of ambient temperature or similar conditions. The source path of the FET is connected to a voltage divider which is so dimensioned that the voltage division ratio (R.sub.2 /R.sub.1) is related to the temperature coefficient (.alpha.) of the base-emitter voltage of the FET and the temperature coefficient (.beta.) of the measuring ionization cell chamber:

Growing community of inventors

Hombrechtikon, Switzerland

Otto Meier