| 摘要 |
PURPOSE:To light a plurality of light emitting diodes with a simple circuit constitution by controlling a series circuit consisting of a plurality of light emitting diodes and level shift diode with a signal source through a comparator. CONSTITUTION:A signal source 1 is connected to a comparator 21 for comparison with a reference signal and the output thereof is applied to the base of a transistor 23. Next, the light emitting diodes 3, 4 to be selectively lighted and a level shift diode 200 are series-connected between the collector and emitter of this transistor 23 and a d.c. voltage of a power source 29 is applied via current limiting resistance 27 between the point of connection of the diodes 3 and 4 and the emitter of the transistor 23. If with such constitution the transistor 23 is turned ON by the signal of the signal source 1 while a voltage is being applied to the circuuit, then the light emitting diode 3 lights and 4 does not light and if the transistor 23 is turned OFF, the above become opposite and only the light emitting diode 4 lights. |
