--Boundary_(ID_g+zFiRPhG8uQ2NFhHxAXhQ) Content-type: text/plain; charset=us-ascii Content-transfer-encoding: 7BIT Dale wrote... >Obviously >there's a better way to handle picking up the base frequency of the >string... anyone got a bright idea that doesn't involve op amps and a >hundred components? What's the matter with opamps? They're handy. They WORK. :) Whatever. Attached is a 3-pole lowpass active filter using about a dozen components that might do the trick. It's flat out to about a hundred hertz and drops off to about -50db at a kilohertz. That oughtta kill your harmonics. Hope this helps... Dave D. --Boundary_(ID_g+zFiRPhG8uQ2NFhHxAXhQ) Content-type: image/gif; name=filter.gif Content-transfer-encoding: base64 Content-disposition: attachment; filename=filter.gif R0lGODlhWAHwAIAAAAAAAP///yH5BAEAAAEALAAAAABYAfAAAAL+jI+py+0Po5y02ouz3rz7D4bi SJbmiabqyrbuC8fyTNf2jef6zvf+DwwKh8Si8YhMKpfMpvMJjUqn1Kr1is1qt9yu9wsOi8fksvmM TqvX7Lb7DY/LeYC63QBA5Od88D2xh7cQGEDYd3hkVwcRaEhoKHgAiUgZpDipB1h4mXeZWZjGKTpK Wmp6ipqqusra6vr6qinZ0Bh5hlnJ5Ong+DmohxsWnJu0yzvL+yc5/MVMjOSMt/jsS/0Ubf2bfb19 gd398w0OOr4kDn5enpO+za5u424d/z4z/2xPD4Ofu5/f0k8JoD8VAg8VHHjiIB+FCEkwlPOwYYiI cChK9GDRTcb+ixs2svHIEQNINSNDVigZymQPlClV6mDZ0uUNmLdkrpNJ06aCnGMmGUOm06FKTI+A BS3B0w+tauSOikjqJdhPW05BQI26tCnTqh2uYtWmlSrXri59+po6NoPXZmljrGXb1sVbuHFXzO1C FJCyTdO03m3zVwvRosgI16q7s+wxoOQMi0X8uOEwwpEM94W8FSEzyo0/7QkMOKQzzp89M8YMuopU Rcsus6aaOibH2BdpU7GtGSdmuzZx5/N9ezcK4FKIqzPOTfhwxcqXD23u3CTy48yhI61ufcR0Xdmv P++uHTv4D9vNjX8q/jyH8krYd3P/9HJkteqtfmQsv2N98mv+pNrfTxZJi2EEYICyJcZfgfr1dxpA 4hjDyXCvGSWhMhEmAphrEy44AWfzTVRNJyk4xt13HTKVEWWlRddZidKdtCFfI054WEI0xkgEfOjJ kuCJYWUGol9o7YjLX0Vq1Mt/PjblYXiRWVQjjzvk9UaSPUqg4l7ePQblWVq+BNYgZnHhWpAKPgCJ f2Hlh0WTHJ6Z1WlSWrmFmxrouBCQ+En5AoR6ihSlgXAyEOgvi9Dpll5yfrmkQJuhCel6kcZ556SE 4rAiI1zW4Mg0VrJTqFo4znJkqbSMKoiplxaJKiiqGnoqo+h9c2hrbLLQS60NeiOnqLKGCmyvfN0a 7JPCDsn+JFhj/iiNrBPBl+RenbpiKyyr8InotK1gyy0w1KLYbbXWjqvjpx6mEyqgzvK4bDTIIshs uju1yq6yWNJLHnt+7vrhpP28m9irjOCbicBoEkzqUtgAzN/CFnoGobRf3ooRxZrCJulJlmJpwWQd fzzgks6NBvGie/pV8EpR2sNTy5zyJpbHMq7pJcaVrQTxuhfX8zING2V5KqkituZtizf3y/PJlfrc c9IjavKrLIyOaRnCcpGWsdMyuEzQvGymuYzNZ201F6JZb9002l17m9+FWWqobZgzmf3mpQP3ZSfS mxz8Wt7MYvuwsCEnxLbFZICtJKGPFiY40kNznOzg84b+aAu6MA+r8287U7ri4nYvzPjGYZIIatqz bW53ZYZ/KO+cq/9NeWGvp652GXEnY3XjepOOeuGeHy05vCgbrTHTtmNNKciSlxk67HqviThQModM ovPJ61PTydXzGquGeuH9J8kUgtv4ahYG/jyf2JuBfNWWG691ovAfHvv2yteOv/zxi9F+2NaL3ifT rW9/zbgR3Ih3P/3lb4ALlAjXCIg7cYlEgA6koFwoUCh3PFA0FvyHyISXQAaebn4KBGCz6EPC2nQQ Vx+UWwsDaKIGXrBRYiseBHOTQhh2CG4aXKE/NlhCEQqxgjmc4Q1ZGMMg6lCGHkziEI2IQRDakIk4 pOL+5aI4Pu4dsYpPbOIU/2dCL6YHiVuk3eyut8QXWXFtU2SZD39YRDGKzI1xHIhPNpQ7yJVRWXTc I6Dql0cnUAl4YHwhFGl4NiXu8HNKK2QUjtQrB73RXom8WuZWRadMDY9MuGuboyYJL3zQhGFxAl/z NslJRqpPUG6JRbPIBctYWktR2/ObFQZpSxRiKH1hJEggpVc95NEFkL8MnhBaZ0i7FNNVd/we3epU x3DoTo9rTAY1RlkM/y3Nj5pTpCX+RE1vSsZrj5CYKXeXzWn2Lo0jrJ9pmie+XUqjbl204zo12blw 5miVWOTmOCaTppWdUJ9D6NQ2q1mO6ZHvaO5KJzj+e3nFcQYvekaLJ/2i+Q5W9S1i5/wfnnSJ0ITC I3v+/CcoTUAwPOrsQg992hjlCEU1EVKmtBMnF9kpRtAhyH5SxGk7fXrF0QRUe1HDKBxDKpRpLstm CrXpUZHqJNjQLXqegigbOWhUG8mHh57iKAJ7ekgVZjULSfloQU/appmosaS3xBRW2aoatb4Vqm1F KzrsWlcCTuWSEMFrXCGooruONa1M5Ok1/RoccfqJr3H4mSsf+ViUZqWc6mzsoLRYrxryAxo8xIsn Jyi8RjC2IvLEJzQx1sO1WpKlaOSnykSxzq/2U6y4Ql+rVlNQ2zqrXfS0pzIpOlDX0mZiXnMh5lL+ C0IatfRAKB2kokJZWU45N4vSA2sEBuNOXqIBiNfFGylxBqOlzja07zQri5x6Wiu274wCGuwVsGkp 3iGCu8KoZv+0S1KoWs279GLtll5JUGdutZOi7ah5/4veRq6qpq79by5X19SfJlizO6UkIa+aS1Rq ksFE9KffMkjMn8UuvjmjKW2R+uGfZBK/gsrwfWP7VBSHaLrmYvHZSLNU0fLywD6gbyefm9zibtil tgLyKwssW+P6Fq6Jde97EDsFH9+0nniBsjys/Egs30PLyWFyNqT8FS9f2cl/FfNhydxkuj4ZzVHm 8mbZXBw3VwLMVYbzmc0MBTp3E89dVnM75OyRIj9/GdDmsfOWDd3nCYsU0YIktEEc7VBBj5nPjWb0 nCENDUzPQc/plfSmI9sVUAtS1B0h9WVPjepUqyYVWj0FWVndXFSoeta0rnVxRvEPXEdF17/1r61/ Dexg53aU7F01sXks7GQre9nMbraznw3taEt72tSutrWvje1sa3vb3O62t78N7nCLe9zkLre5x1AA AAA7 --Boundary_(ID_g+zFiRPhG8uQ2NFhHxAXhQ)-- -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body