AC-DC CONVERSION CONSTANT CURRENT CIRCUIT

PURPOSE:To dispense with full-wave rectification by a method wherein a constant current is outputted through a reverse voltage checking element, smoothed and converted into a DC voltage and the opposite ends of a smoothing element are connected to a load circuit. CONSTITUTION:By the operation of a reverse voltage checking diode 16, a constant current is outputted to a smoothing capacitor 17 only when a positive voltage is impressed on an emitter E of a transistor 14 for control, In order to ensure the same amplitude of the constant current as usual, an AC voltage AC2 is made larger than a usual transformed AC voltage by regulating transformation in an AC power supply part 11 The AC voltage AC2 is given from the AC power supply part 1 to a constant current circuit 3, the transistor 14 for control in the constant current circuit 3 operates supply the constant current to the smoothing capacitor 17, only when the positive voltage is impressed on a terminal (a). and thereby the constant current of a DC component is supplied to a load circuit 4. In other words, it is unnecessary to execute usual full-wave rectification for supplying the constant current to the load circuit, and thus lessening of the number of components and reduction of the cost can be attained.