Abstract: A circuit arrangement for a light barrier for detecting absence or presence of an opaque object at a given location, includes an apparatus for transmitting a signal in response to the disposition of the object, an apparatus for receiving the signal, an apparatus for evaluating the received signal, and an apparatus for initiating a follow-up operation in response to the evaluation of the received signal. The transmitting and receiving apparatus is formed as a reflex light barrier, a digital filter is connected between the transmitting and receiving apparatus and the evaluating apparatus includes two parallel-connected bistable flip-flop circuits, wherein one of the flip-flop circuits has an inverted clock input.