A switch is disposed between a power source and an activating element for activating a passenger protection apparatus. The switch detects a vehicle collision and closes its contacts to supply activating current to the activating element. A capacitor is connected in parallel with the activating element in order to charge momentarily when the switch closes. In this manner, it is possible to activate the activating element accurately because the activating element continues to be supplied with activating current by means of the charging voltage of the capacitor, even when the switch only closes for a time which is insufficient to activate the activating element.