Abstract: A start circuit (1) includes a series connection of a glow switch (10) and a safety switch (12), which are each provided with an enclosed space (10a, 12a), with a pair of current conductors (10b, 10c resp. 12b, 12c) which enter the enclosed space and with a bimetallic element (10e resp. 12e) which is arranged in the enclosed space and which is connected with one (10c resp. 12c) of the current supply connectors. The enclosed space (10a) of the glow switch (10) is provided with an ionisable filling. The glow switch (10) is opened in cold state. The safety switch is closed in cold state. The start circuit (1) comprises a heat source (11) for opening the safety switch (12). The start circuit further comprises a heat source for keeping the safety switch (12) open which is formed by an ionisable filling in the enclosed space (12a) of the safety switch (12).

Abstract: A circuit arrangement for operating a discharge lamp (LA), provided with input terminals (K1, K2) for connection to a supply voltage source. A rectifier (D1-D4) is coupled to the input terminals for rectifying a supply voltage delivered by the supply voltage source. A capacitor (C2) is coupled to the rectifier and a DC-AC converter (III) is coupled to the capacitor and is provided with terminals for accommodating a discharge lamp. The circuit arrangement is also provided with a circuit I (R1-R6. T1, T2, C1, V, VI, VII) for detecting periodic current pulses having an amplitude greater than a given value W1 and with a circuit II (IIa, S1) coupled to the circuit I for changing the operational state of the circuit arrangement. As a result, damage to the circuit arrangement is prevented when the circuit arrangement is used in combination with a dimmer unsuitable for the circuit arrangement.