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JoshwaBurke 28th November 2012 09:10 PM

Multi Active Band-Pass Filter Equalizer (Guitar Pedal)
I'm building a simple equalizer guitar pedal. I have three simple band-pass active filter circuits in the picture.

Low (Bass) center frequency band: 78Hz (5% tolerance)
Middle center frequency band: 1.15kHz (2% tolerance)
High (Treble) center frequency band: 7.8kHz (2% tolerance)
Equalizer Control will vary up to +/- 15dB per band

I believe I have met the specifcations above. Now I'm breadboarding a working model.

Could someone help me with a feedback loop?
Any help or suggestions on my schematic would be appreciated

Cal Weldon 30th November 2012 03:59 PM

I've moved this to here. Hopefully you'll get a response now.

JMFahey 30th November 2012 04:54 PM

Well, for one you just can't wire together 3 Op Amp outputs, they short each other.
What are you trying to design?
Some new kind of equalizer?

JoshwaBurke 1st December 2012 04:17 PM

Thank you for the moving the thread. =) Yeah, they should not be tied together. I have three separate band-pass filters on my breadboard at the moment. Just my bass band-pass is connected in the picture below. I was expecting to hear a distorted tone since I don't have my split rail power supply connected, but I can only hear a tone when my 100k pot (gain) is almost 100%

I'd also like to be pointed toward some information on a split rail power supply using a single 9v battery. Any help will be VERY appreciated.

here is a picture my of what I have wired at the moment.

I used this wiring diagram for the pedal itself.

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