| 摘要 |
PURPOSE:To obtain a stable constant-voltage characteristic, and to scarcely cause a measuring error, by connecting in parallel two systems of series circuits consisting of a resistance and a light emitting diode, connecting a load in parallel with one light emitting diode, and setting the light emission start voltage of the other light emitting diode to high voltage. CONSTITUTION:A series circuit of a resistance 12 and an LED13, and a series circuit of a resistance 15 and an LED16 are connected in parallel, a load circuit 17 is connected to the LED16 in parallel, and as for the LED13, its light emission start voltage is set higher than the voltage of the LED16. Also, in an area (a), a current flows to the load circuit 17, and does not flow to the LEDs 13, 16. When the voltage is in an area (b), the LED16 is light emitted. Also, when the voltage is in an area (c), drop voltage in the forward direction of the LED16 shows a stable constant-voltage characteristic. When the voltage further rises and exceeds the light emission start voltage of the LED13, the LED13 is light emitted to display that the constant-voltage is supplied to the circuit 17. |
