Single-phase switching apparatus having a voltage supply for a movement signalling device

摘要

The invention relates to a single-phase switching apparatus for a load which can be connected to the mains, having a switching arrangement for producing a supply voltage for a movement signalling device or the like which can be installed in a flush-mounted switch socket of a conventional light switch, and, for use in conventional flush-mounted switch sockets, proposes, in association with the supply of a constant supply voltage and electrical-shock protection, even when no neutral conductor is present, that the circuit arrangement has a changeover switch (15) by means of which the primary winding (63) of a transformer (64) can be connected in series with the load (62), on whose secondary winding (68) the supply voltage is picked off, and that a reverse-parallel circuit consisting of two diodes (65, 66) can alternatively be connected in series with the load (62) by means of the changeover switch (15), a sub-winding (67) of the primary winding (63) of the transformer (64) being connected in parallel with the two diodes (65, 66). The diode threshold voltage is transformed up by means of the sub-winding to the supply voltage, the impedance of the primary winding (63) at the mains frequency being a multiplicity of times greater than the resistance of the load (62). The forward resistance of the diodes (65, 66) is considerably less than the impedance of the sub-winding (67) at the mains frequency. <IMAGE>