Where's the High Pass in a State Variable LM13700 Filter?

Discussion in 'Circuit Help' started by osterchrisi, Jul 4, 2011.

  1. osterchrisi

    osterchrisi

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    Hi!

    I wanted to build a quick and not to hi-fi voltage controlled notch filter so I went for the LM13700 state variable filter. By summing up lopass and hipass you usually should get a notch filter. So here's the schematic:
    [​IMG]

    Actually the hipass should be found at the non-inverting input of the second half of the LM13700, right? Thing is, there's nothing really useful comming out, am I overseeing something? Where's my hipass? :(

    Thanks for any advice!!
     
    osterchrisi, Jul 4, 2011
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