Abstract: An energy coil together with an IR receiver form a mechatronic component of an ignition lock. The component is disposed in a receptacle of the ignition lock such that, with the ignition key inserted the component, it is disposed in close proximity to an energy coil and an IR transmitter of the ignition key and it is aligned with the latter.

Abstract: An anti-theft system for a motor vehicle includes a transceiver disposed in a motor vehicle and a portable transponder. If a magnetic alternating field of the transceiver is turned on, energy signals are transmitted inductively to the transponder, where they charge an energy storing device. As soon as the alternating field is turned off, a transponder oscillating circuit oscillates at its resonant frequency. This oscillation is transmitted inductively back to the transceiver. In the process, the resonant frequency is measured. Then, the exciter frequency of the alternating field is adapted to the resonant frequency of the transponder, so that the inductive energy transmission is as effective as possible in subsequent charging operations.