Patent ID: 8508235

Claim:
An electronic device comprising a circuit board having a set of input contacts, a set of output contacts and an electrical circuit connected between the input contacts and the output contacts, and a controller, wherein the controller is configured, at least once during operation of the device, to apply a predetermined test signal, configured as at least one of a pulsed signal, an alternating current signal with a predetermined frequency and an alternating current signal with a sequence of predetermined frequencies, to the set of input contacts, to tap off a response signal at the set of output contacts, to carry out a signal analysis on the response signal, to compare a result of the signal analysis with an expected value stored in a memory of the controller, and if no match is determined between the signal analysis result and the expected value, to prevent, at least partially, further operation of at least part of the device, wherein the electrical circuit is configured as a passive network having a characteristic transfer function and comprises at least one capacitive element comprising a conductor surface which, in the installed condition, forms a capacitor with a corresponding, device-side conductor surface which, in the installed condition, is connected via a contact element to the electrical circuit, whereby the capacitance of the capacitive element in the installed condition differs from the capacitance of the capacitive element in the uninstalled condition.