The optoelectronic isolation circuit between TTL and relay

Published:2011/5/28 0:43:00 Author:chopper | Keyword: TTL, relay, optoelectronic isolation circuit | From:SeekIC

In this circuit,it uses photocoupler to make the circuit between TTL and relay gain the isolation of 100GΩ,and eliminates the effect to TTL circuit from noise of relay as well as spike voltage.When the input signal of TTL is high,Q1 is conducted,and LED has no current.And there is no light incidenting to detectors.At this time,photoelectric diode has the bigest resistance value of 5GΩ.Therefore,Q2 is inconductive,so is Q3.Thus,no current passes through the coil of relay.



Reprinted Url Of This Article:
http://www.seekic.com/circuit_diagram/Amplifier_Circuit/The_optoelectronic_isolation_circuit_between_TTL_and_relay.html

Print this Page | Comments | Reading(3)