Hi there, Martin. The standard approach is to use an audio isolation transformer. I=20 have had very good success with issues such as what you are describing. Shameless plug: my company sells little isolation transformer modules=20 for not much money. These use a semi-custom transformer from=20 Datatronics and really do work very well. I think that cost is=20 around Can $25 in singles (soon to increase due to supplier cost=20 increases) plus shipping. Let me know if you want to try this out. I'll arrange to send one to=20 you and you can either pay for it or return it as you see fit. dwayne At 09:06 PM 11/14/2018, Martin McCormick wrote: > Are there any optoisolators that are suitable to carry >analog audio over the normal frequency range of 20 to 20000 HZ? > > What I am trying to do is feed audio from a radio >receiver across the room to an audio mixer. There are enough >computers and switching power supplies in the room that noise is >picked up by the shield of the audio line and ends up being >induced in to the radio via the chassis ground. > > If optoisolated, the noise would still be on the cable >but the path for it would break completely at the output side of >the isolator. > > I am not holding my breath but I figured I can ask >whether any such device exists or maybe a conventional >optoisolator will work if one conditions the input to the LED to >negate the distortion one would get by feeding audio biased to >light the LED halfway during silence and then go to full >brightness and almost fully off at maximum volume. > > One would hope for linear response. > > Thanks for any good ideas. > >Martin McCormick WB5AGZ --=20 Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA 780-489-3199 voice 780-487-6397 fax 888-489-3199 Toll Free www.trinity-electronics.com Custom Electronics Design and Manufacturing --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .