urgent

Discussion in 'The Projects Forum' started by engy, Jun 19, 2009.

  1. engy

    Thread Starter New Member

    Mar 27, 2009
    7
    0
    i tried this circuit but unfortunately it didn't work .... i replaced the meter with led array workin with lm3915,at all the leds doesn't change they lighted uniformly plz tell me is this circuit ir wrong ? ? can i try it with proteus and if it's yes then what type of input since there's no mic found in the program.....
     
  2. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    Need you to post your schematic.

    hgmjr
     
  3. engy

    Thread Starter New Member

    Mar 27, 2009
    7
    0
    sry here's the schematic
     
  4. CDRIVE

    Senior Member

    Jul 1, 2008
    2,223
    99
    I'm sorry! I placed my fingers on my monitor and tried a Vulcan Mind Meld but no go. I guess you're just going to have to post the schematic. :rolleyes:
     
  5. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    I can see the attachment, now.

    Thanks,
    hgmjr
     
  6. CDRIVE

    Senior Member

    Jul 1, 2008
    2,223
    99
    Well, was it working with the meter? The LM3915's input pin is going to be referenced to ( - ) GND, which the meter isn't.
     
  7. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Since Audioguru figured it out - is your microphone an electret type? This won't work otherwise.
     
  8. CDRIVE

    Senior Member

    Jul 1, 2008
    2,223
    99
    While the circuit appears to employ an electret mic I don't believe that a dynamic mic wouldn't work there. R1 is 10K, so it's doubtful that it would have that much effect on a 1K dynamic element. I could be (CYA) wrong though. :)
     
  9. engy

    Thread Starter New Member

    Mar 27, 2009
    7
    0
    the mic used is electric mic,,,,i connected the (+) of the meter with the input of the lm3915, the circuit worked but i faced a problem which is ther're no variation in the led's brightness,, i think that this variation must be done by receiving different sound intensity and then variation in output volt.
    may be the mic connection is wrong.... what can i do ? ? ?
     
  10. CDRIVE

    Senior Member

    Jul 1, 2008
    2,223
    99
    There isn't supposed to be a variation in the LEDs brightness when using the LM3915. Also, did you read what I posted in post 6?
     
  11. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    The + of the meter in the circuit has a continuous DC voltage. Your LM3915 circuit displays how much DC voltage.
    You need to use a resistor to ground at the input of the LM3915 then a coupling capacitor for the signal.
    I sketched the correction but the LEDs will look like a dim blur unless you make the "half-wave peak detector circuit" that is shown on the datasheet of the LM3915.
     
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