First resistors (R1, R2) for setting a
forward current value are connected in series to light-emitting diodes (LED 1, LED 2) respectively to constitute first serial circuits (112, 113), which are connected to an input terminal (111). Second serial circuits (115, 116) are connected in parallel to the first serial circuits (112, 113) respectively. The second serial circuits (115, 116) are constituted by a combination of a
Zener diode (ZD1) and a second
resistor (R3), and another combination of a
Zener diode (ZD2) and a second
resistor (R4). When a higher
voltage than rated voltages of the light-emitting diodes (LED 1, LED 2) is applied, the Zener diodes (ZD1, ZD2) shunt current into the second serial circuit (115, 116) to allow the light-emitting diodes (LED 1, LED 2) to light up at desirable luminance levels different from each other. When a supplied power
voltage decreases, current is not shunted, so that the same
forward current flows through the light-emitting diodes (LED 1, LED 2), allowing the light-emitting diodes (LED 1, LED 2) to go off at the same timing.