| 摘要 |
PURPOSE:To enable an LED to be lit with a cell having an electromotive force lower than the forward voltage, by composing a series circuit of a cell, a coil and a switch element, and by charging and discharging the coil by means of the switching element. CONSTITUTION:A cell 1a, a coil 6 and NPN transistor 4 are connected in series. An infrared LED 3 and the coil 6 are connected in series in the direction corresponding to the direction in which forward current is caused to flow by the self electromotive force of the coil 6 when the transistor 4 as a switching element is open or OFF. In the above construction, the peak current IT/2 of current iD of the infrared LED 3 can be arbitrarily set either by selecting a suitable value for a self inductance L of the coil 6 or by properly setting an ON time of the transistor. Accordingly, a cell having an electromotive force lower than the required forward voltage can be used for actuating a light-emitting diode with predetermined forward current. |
