| 摘要 |
<p>PURPOSE:To enable the protection of load and the protection of power source to be performed by series-connecting a parallel circuit of a voltage dividing resistance and a constant voltage element to the series circuit of a light emitting diode and a current limiting resistance so that the detection signal chanes sharply at the abnormality. CONSTITUTION:When current flows in a current detecting resistance 1, current flows in a light emitting diode 3 by a current limiting resistance 5 and a voltage dividing resistance 12, causing a photo transistor 4 to conduct and voltage to be generated across the resistance 6. When the current flowing in the detecting resistance 1 increases and the voltage across the voltage dividing resistance 12 reaches the conduction voltage of a diode 13 for constant voltage, current begins to flow in the diode 13 and the voltage across the voltage dividing resistance 12 no longer increases, resulting in that the voltage increaments are all applied to the current limiting resistance 5 and light emitting diode 3. Hence, when the current flowing in the detecting resistance 1 exceeds this value, the output voltage sharply increases, thus the protection of the power source or load at the abnormality may be rapidly accomplished.</p> |
