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  1. eboaylag

    EEG circuit - need help please!

    Are you talking about for the notch? That makes sense. I'll do that!
  2. eboaylag

    EEG circuit - need help please!

    In searching for film capacitors I realized I needed to scale things, so here's the final result: 2.2uF was the highest value I saw on the website I'm ordering from, so I scaled things to match that value. New cutoff values: High Pass cutoff: 7.234315595. Low Pass cutoff: 32.8832527. Notch...
  3. eboaylag

    EEG circuit - need help please!

    Alright, thank you! You've been a huge help. @AnalogKid , if there isn't anything else on scaling/altering the circuit, I'm going to purchase parts tonight! Please let me know if there are any final tweaks needed, and thanks for all your help, too!
  4. eboaylag

    EEG circuit - need help please!

    Alright, thank you! I'll look into shielded enclosures if the signal isn't what I want after building the circuit. In terms of the actual circuit though, do you think there are any adjustments that need to be made? Component-wise, filter-wise, anything!
  5. eboaylag

    EEG circuit - need help please!

    I'm really sorry to bother, but could I have a little more help here? I'm unsure of if I need to scale things / what needs to be fixed and I'd really like to purchase parts soon to get this started! I really appreciate everything so far! @AnalogKid @Gryd3
  6. eboaylag

    EEG circuit - need help please!

    Should I be using film capacitors for the whole circuit?
  7. eboaylag

    EEG circuit - need help please!

    I actually won't be using this circuit inside a shielded enclosure. Should I still scale the filters up a bit? Should I be scaling this one down then?
  8. eboaylag

    EEG circuit - need help please!

    Alright. Here's what I've got: The ADN stage has a gain of 89.2 by the formula G = 1 + 49400/560. This stayed the same from the Instructables circuit. The second order filters were adapted from this page, and the component values were kept equal as per AnalogKid's suggestion. The high pass...
  9. eboaylag

    EEG circuit - need help please!

    What's the best way to take figuring out the component values for the whole circuit? I've never done something like this before, so I'm a little lost on where to start. I have the formulas for the filters, but the amplifier I'm still unsure about.
  10. eboaylag

    EEG circuit - need help please!

    @AnalogKid , would something like this for the notch filters be better? Twin "T" networks, with high Q. The second one even has a potentiometer for adjustment.
  11. eboaylag

    EEG circuit - need help please!

    Thanks, all! Alright, so I'm going to work on revising the circuit with the new filters and try calculating component values. I'll post again when I have a circuit ready, or if I have any issues. Also, do you think using simple voltage followers between stages would be beneficial? I've done...
  12. eboaylag

    EEG circuit - need help please!

    If it helps, I bought ALPTA brand passive gold plated copper EEG electrodes from Ebay. I bought touchproof adapters from PlasticsOne, and soldered the ends of the adapters to male jumper cables so they fit in my board at pins 2 and 3 of the AD260, and one into the ground power line of my circuit...
  13. eboaylag

    EEG circuit - need help please!

    Alright, so I've come up with this in terms of basic schematic layout/format. Working on the calculations, but I wanted to check and make sure this was correct before moving too far ahead. The op-amp filters are all from the websites you mentioned. Alpha and beta wave amplitudes are around...
  14. eboaylag

    EEG circuit - need help please!

    So, the order should be: amplifier (ADN), notch filter, then my two filters (one low one high)? Is there any use for the potentiometer anymore (or is that up to my design)? Also, for the "fake brain", would I use an audio cable and alligator clips to get the fake signal from an MP3 of 7Hz-30Hz...
  15. eboaylag

    EEG circuit - need help please!

    Do you think I'll be able to create a new circuit, but using the same parts? My issue is that I'm supposed to make this circuit three times over, so I have the parts available for three circuits from this schematic. These are the only parts I have available, and I'd prefer to avoid purchasing...
  16. eboaylag

    EEG circuit - need help please!

    Thank you so much for your help and patience. I really appreciate it! I'll be going through and checking everything tomorrow. One more question though: will I need a physical oscilloscope or would a virtual computer one suffice? I'm sure a physical one would be better especially if the sound...
  17. eboaylag

    EEG circuit - need help please!

    The electrodes are used to read signals from the brain off the scalp. In the circuit they're placed at pins 2 and 3 on the instrumentation amplifier AD620AN, and for input signal they're placed on the scalp. I unfortunately do not know what value of signal to expect or how to test it on which...
  18. eboaylag

    EEG circuit - need help please!

    @(*steve*) sorry, I'm just lost and I didn't even know how to reply to @AnalogKid . The 620 actually has two inputs, which are the two "reading" electrodes. I'm not sure what I'm supposed to get through its output, nor how I'm supposed to test it. I know it's supposed to amplify the electrode...
  19. eboaylag

    EEG circuit - need help please!

    Looking for alpha/beta brainwaves, which range from 7-30Hz. Should I test the circuit on a Mac? What's their frequency response? Also, would reading through an Arduino via USB 2.0 bypass the frequency response issue?
  20. eboaylag

    EEG circuit - need help please!

    How would you recommend testing it?
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