re need tone decoder circuit in article hplsla hp com tomb hplsla hp com tom bruhns writes does anybody out there have a circuit that will decode a hz tone use a ne tone decoder pll chip my impression it s not an area i ve played with much is that the much beloved ne is basically obsolete if you want to detect a khz tone set a switched capacitor filter chip to that frequency feed your input to it and see if anything comes out the other end the ne was what you used when good clean bandpass filters were hard to do nowadays they re easy and the results are better all work is one man s work henry spencer u of toronto zoology kipling henry zoo toronto edu utzoo henry
