| 摘要 |
<p>PURPOSE:To improve noise resistance by series-connecting a Zener diode to a LED with polarities made opposite mutually. CONSTITUTION:Zener diode 5 has a low Zener voltage as compared with the voltage of power supply 1 and conducts, with switch 2 closed, to feed a current to LED3 in the forward direction, so that LED3 will emit light. Even if noises are induced at connection line 11, the LED remain conducted when the peak value of noises is below the sum of the Zener voltage and forward voltage of the LED. As a result, the noise blind sector expands remarkably and the noise resistance also improve.</p> |
