fast opto-isolator

fast opto-isolator When a computer drives external equipment, it is often required that the earths between them are electrically isolated from one another. The simplest way of effecting this is by an isolating transformer. When, however, the system works at high frequencies, it is much better to use an opto- isolator as proposed here because that is capable of following the fast data transfer. The opto-isolator is driven via a TTL gate. The transistor in the opto- isolator drives comparator IC,. The trigger threshold of this device is set with P,. Low-pass filter R2-C, prevents spurious triggering of the comparator by noise pulses.