Abstract: An emergency-lighting device for operating a light-source, in particular an LED, comprises an energy storage unit, a charging circuit, to be supplied with a mains supply voltage (Uin), for charging the energy storage unit during charging operation, the charging circuit comprising a potential separation, and also a driver circuit, supplied by the energy storage unit during emergency-light operation, for operating the light-source. Furthermore a control unit is provided which is designed for monitoring the state of the mains supply voltage (Uin) during charging operation and, when an emergency condition is detected, for activating emergency-light operation, the control unit ascertaining the state of the mains supply voltage (Uin) on the basis of operating variables of the emergency-lighting device which are measured on the output side of the charging circuit.

Abstract: The transmission branch of an interface circuit has a transformer. On the input side there are applied to the transformer, for example from a controller, high-frequency impulses. The output side of the transformer controls a switch, such as for example a power transistor, which modulates the desired digital signals onto a connected bus line.

Abstract: A control circuit for an operating device for lighting devices, wherein a return signal is supplied to an input of the control circuit by the lighting device, and the control circuit has an error detection block that recognizes at least two different types of lighting device errors by means of the return signal applied at said input.