In sometimes we have to relay sound signal from the one circuit goes to again the one circuit. By the separation Ground depart may because , want the safety from the high voltage. From the one circuit flows to come Ground.

This circuit solves a problem by live opto copper meet sound frequency the crazy low about 1% this circuit also electric low many current about 10mA only. Lead circuit this example goes to use such as apply to TV the past generation that have no transformer make extend a contract at the sound reaches power Amplifier outside can get into trouble.

When use this circuit can separate power supply depart TV circuit get. For fining all detail please see in the circuit please yes.