How to reduce microphone sensitivity for this circuit

Discussion in 'General Electronics Chat' started by bobby_tct, May 14, 2019.

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  1. bobby_tct

    Thread Starter New Member

    Jan 6, 2011
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    I bought a sound switch from aliexpress but was to sensitive to slightest sound. I came across a comment showing a modified circuit by adding a potentiometer which claimed to be able to control the sensitivity of the microphone at switching on the circuit.. Problem is i do not know where should i attach the potentiometer to.. would be grateful is someone could help me out. Thanks. :) I have attached 2 photos. 1st is original circuit. 2nd is the modified circuit. Looks like the potentiometer is attached to the L393 but not sure which pin..

    MOD: processed your images, to make them readable.E
     
    Last edited by a moderator: May 14, 2019
  2. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
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    Do you have a link to the original part?
     
  3. bobby_tct

    Thread Starter New Member

    Jan 6, 2011
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  4. Wolframore

    Active Member

    Jan 21, 2019
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    looks like he removed the LDR on the PCB from pic 1 to pic 2... If you added a potentiometer one leg of the LDR and to one of the fixed ends as per below and connected a variable end to one of the holes

    [​IMG]

    like this:

    upload_2019-5-14_8-30-11.png

    Try a 10K potentiometer
     
    Last edited: May 14, 2019
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  5. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
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    Well, that was helpful :confused:
    Not!
    (Update: was only referring to the glut of information on the aliexpress listing)
     
    Last edited: May 14, 2019
  6. bobby_tct

    Thread Starter New Member

    Jan 6, 2011
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    Any idea which pin should i solder the potentiometer to?
     
  7. Wolframore

    Active Member

    Jan 21, 2019
    750
    204
    should not matter... one goes to pot the other back into one of the holes where you removed the LDR... why are you posting info for the comparator? If that's on there... which makes sense... leave it alone. Just use the holes where you removed the original LDR.
     
  8. bobby_tct

    Thread Starter New Member

    Jan 6, 2011
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    Ok. Will try it out. Thanks ya. :)
     
  9. Audioguru

    Expert

    Dec 20, 2007
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    Why do people buy such cheap junk? it has no description and no specifications.
    Is it supposed to turn on a light only when it is dark and if there is any kind of sound?
     
  10. Wolframore

    Active Member

    Jan 21, 2019
    750
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    * shrug... i can't read Chinese... but come to think of it I wouldn't trust this on mains voltage!

    [​IMG]
     
  11. Audioguru

    Expert

    Dec 20, 2007
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    You get what you pay for. The cheap junk is not certified to be safe.
    Since AliExpress cannot read English numbers they say that you get 10 of the modules for only $1.69US.
     
  12. Wolframore

    Active Member

    Jan 21, 2019
    750
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    well no wonder people buy them... they are $0.13 each... no clue how they do that...

    I was shopping for a chip the other day ... chips are about $1... PCB module with chip and regulator and some other stuff $1.23.
     
  13. bertus

    Administrator

    Apr 5, 2008
    19,581
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    Hello,
    Working 9 to 9 for 6 days on cheap labour.
    The parts in mass production.

    They also seem not to care about safety.
    The circuit contains a mains powered circuit, wic the TOS does not allow.

    Bertus
     
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