A power supply for led traffic light

A power supply for an LED traffic light simplifies a structure without an additional dimming control circuit inside by providing the dimming control signal to the LED traffic light after rectifying and constant-voltage controlling the dimming control signal. A rectifier(10) is positioned in a tip part of a power supply device and rectifies the AC to the DC when the AC voltage is applied from a traffic signal controller(1). The rectifier passes the DC through when the direct current voltage is applied. A voltage detecting part(20) detects the voltage rectified in the rectifier and blocks the voltage supply to the LED traffic signal when the detected voltage is not the normal voltage. A constant voltage maintaining unit(30) maintains the voltage rectified in the rectifier to the proper voltage. A dummy load(60) is connected to the rear end of the rectifier. A load control part(50) prevents the current from flowing in the dummy load when the waveform is not a normal lighting signal by analyzing the waveform of the voltage rectified in the rectifier. The load control part control to flow the current in the dummy load when the waveform is the dimming control signal.