"Winston" wrote in message
...
Dana wrote:
Looking to notch out a 400HZ whine from some audio circuits connecting
remote manned sites to a central location.
(Snip)
Problem with that is getting the inductors locally.
Up here In Fairbanks our choices are very limited.

Thanks.

Synthesize your inductor with a Gyrator!
Here is a schematic for a graphic equalizer section using virtual
inductors. Extremely cool if it works.

http://www.4qdtec.com/graph.html

Since electrical supply is really limited at the sites in question, they are
remote mountain tops, a passive device would be best bet.
But you are right this device on your link looks very neat. Will try
building it just to see how it works, may be able to use it at one of the
microwave hub sites where I have more available electricity, and the audio
circuits in question do go through another channel bank.

--Winston