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  1. Maglatron

    Sallen Key Low Pass Filter, bandpass filter

    so do you need to put the 470r resistors or are they in built, thanks
  2. Maglatron

    Sallen Key Low Pass Filter, bandpass filter

    cool so I've bookmarked that page I am going to read it looks useful but doesn't address the original problem of modifying the circuit with lifted grounds please take another look at it! I want bar graph mode with one input to control the 20 LED's
  3. Maglatron

    Sallen Key Low Pass Filter, bandpass filter

    okay I'm confused - surprise surprise, so I found this in the datasheet it says that pin 9 should be linked to positive for bar mode but on the schematic you provided a while back the pin 9 of the second chip is not connected at all and the pin 9 or the first chip is conecteed to the cathode of...
  4. Maglatron

    Sallen Key Low Pass Filter, bandpass filter

    I can't find the comment in the datasheet!
  5. Maglatron

    Sallen Key Low Pass Filter, bandpass filter

    thanks! ok I'll solder it in and see if it helps!
  6. Maglatron

    Sallen Key Low Pass Filter, bandpass filter

    thanks and is it imperative to have the 22k resistor in the lm3914's circuit?
  7. Maglatron

    Sallen Key Low Pass Filter, bandpass filter

    term 1 to the resistor of the pre-amp? where 12k and 10uF cap is connected the 22k resistor I mentioned is the one in this picture over LED 11 of the lm3914 bar graph LED drivers
  8. Maglatron

    Sallen Key Low Pass Filter, bandpass filter

    from what I understand omnidirectional means it doesn't matter which way round I wire the mic
  9. Maglatron

    Sallen Key Low Pass Filter, bandpass filter

    So I believe that the circuit is rigged up properly now don't know if the mic polarity is correct this is the data sheet for the one that I have https://www.mouser.co.uk/datasheet/2/670/cma_4544pf_w-1776632.pdf the LED's are not responding to the low frequency and when I was packing away I...
  10. Maglatron

    Sallen Key Low Pass Filter, bandpass filter

    So restarted the lm3914 bar graph LED driver circuits! just got to fit the 22k resistor and the LED's and join pin 9 of chip one to one of chip two and plug it in and see if it works out better this time will take pictures of results this time! thanks
  11. Maglatron

    Sallen Key Low Pass Filter, bandpass filter

    anyone?
  12. Maglatron

    Sallen Key Low Pass Filter, bandpass filter

    so alor, I connected up the bar graph LED's and switched on the circuit all of the leds flash but then only the top 5 segments light and some are faint and some are solid so I think that I may have a problem with this part of the circuit, going to redo it next time any ideas why the top LED's...
  13. Maglatron

    Sallen Key Low Pass Filter, bandpass filter

    soldered half or the ribon to the bar graph LED's another 10 wires 20 joints and then the power lines too, hopefully get another chance to go on to the project tomorrow! thanks
  14. Maglatron

    Sallen Key Low Pass Filter, bandpass filter

    I will be (hopefully) going on the project at twilight to solder in the LED's and the mic so we will soon see if it works, thanks! there are easier and cheaper ways of doing this spectrum analizer project but I wanted a certain look to the display (a kind of retro look)
  15. Maglatron

    Sallen Key Low Pass Filter, bandpass filter

    UPDATE: few action shots and pictures still not finished the first column but only have to solder in the first LED bar graph column and the ribon cable is what I'm going to use to connect them! thanks, also not attached the mic yet and the wires that are loosely knotted are the power cables!
  16. Maglatron

    Sallen Key Low Pass Filter, bandpass filter

    so now have started the lm3914 bar graph driver circuit one or two more sessions should see if it works!! thanks
  17. Maglatron

    Sallen Key Low Pass Filter, bandpass filter

    so I'm going to be taking photos soon making progress still concentrating my full effort into this light board project should have the first column lit soon!
  18. Maglatron

    Sallen Key Low Pass Filter, bandpass filter

    I must say it's looking awfully wirey I thought that I could make traces with the solder spots but it's not that easy they the solder blobs seem to like to stick in spots of two it's hard to join three in a row but the connections are made so hoping for the best! I'll take photos
  19. Maglatron

    Sallen Key Low Pass Filter, bandpass filter

    So now I have done the pre-amp, amp and a reference ground for the amp and a couple of the filters. going to build the filter next, step by step slowly slowly
  20. Maglatron

    Sallen Key Low Pass Filter, bandpass filter

    Pre-amp now on the main board! take pics when I can
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