Problem in 16 way clap switch

Discussion in 'The Projects Forum' started by vikas_madhu, Jan 21, 2014.

  1. vikas_madhu

    Thread Starter New Member

    Jan 21, 2014
    1
    0
    http://electronicsforu.com/electron...e.asp?sno=1146&article_type=1&id=988&tt=unhot in the given link of 16 way operated clap switch i am facing some problem.

    instead of load i connected LED's which glow according to the binary digits given in the table. But the problem is when i clap i couldn't observe any change in LED's but i can observe these changes when i remove the end of microphone which is connected to the ground and reconnect it.
    so if i repeatedly connect and disconnect then i can observe the changes in output but not when i clap. where might be the mistake?
     
  2. ericgibbs

    AAC Fanatic!

    Jan 29, 2010
    2,503
    380
    hi,
    Which type of microphone are you using.?
    Also does adjusting VR1 have any effect at all on the sensitivity.?
    E
     
  3. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,800
    1,103
    Using a poorly-designed circuit :). T1 is not configured for reliable amplification of small signals. Moreover, if VR1 is ever set to minimum (zero) resistance then T1 shorts the 5V supply when conducting and possibly dies (so might already need replacing).
    Try adding the following:
    1) 33k resistor from T1 base to ground,
    2) 330 Ohm resistor between T1 emitter and ground,
    3) 10uF (or greater) capacitor in parallel with the 330 Ohm resistor.

    Edit: Alternatively, you could try simply connecting a 10k resistor between IC1 pin 2 and ground.
     
    Last edited: Jan 21, 2014
  4. TANDBERGEREN

    Member

    Jan 20, 2014
    74
    4
    No need to make such complicated cirquit out of this.
    First of all the micophones function should be verified.
    If You use a standard electret micophone, there should be a good signal at the signal output of the micophone.
    Some of theese have separate positive terminal and signal output.
    Verify this aswell.

    Remember this is not for any "hifi"-purpose, just to deteckt the clapping itselves.
    But at least a kiloohm resistor in series with the potmeter VR1 would be a good choice.
    Also I would have replaced the capasitor C1 with a 1uF film type.
    The resistor R1 seems a bit too big.
    Refeer to the data for the microphone here, and you probably should have a resistor in the area of a couple of kiloohms there.
     
  5. GopherT

    AAC Fanatic!

    Nov 23, 2012
    6,057
    3,819
    I agree with previous two posts. Mic amplifiers is really a bad design, and the shoe thing is much too complicated. Look for something simple. You only want saturation/cutoff swings, not full dynamic range.
     
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