Clapper Switch output "on time"

Discussion in 'The Projects Forum' started by JDR04, Jan 30, 2013.

  1. JDR04

    Thread Starter Active Member

    May 5, 2011
    This circuit is from afrotechmods on YOUTUBE. I have found afrotechmods very useful for my studies. I'm using it as a learning circuit so have a few questions to ask.....

    I know the output "on time" can be varied by changing the values of C2 and R5. I'm trying to achieve an "on time" for the LED (D2) for 1 second but have noticed that this seems to vary in relation to how loud the clap is. The softer the clap, the shorter the "on time seems to be. Can somebody tell me how I can achieve a stable 1 second output or "on time" for the LED at D2?

    I would also like to convert the circuit so I may use a normal 9V battery. What would I need to consider when it comes to the component values etc?

    How do I determine the maximum amplification that can be achieved by manipulating R4 and R3?

    Lastly, I have replaced R6 with a 100K potentiometer so I can raise or lower the threshold of the comparator. Is this the right approach?

    Once again, thanks for your help. JDR04
    Last edited: Jan 30, 2013
  2. praondevou

    AAC Fanatic!

    Jul 9, 2011
    The exact time depends on how much the 10u capacitor is charged.

    Everything on the right side of the diode D1 except R8 and the LED of course you can replace by a monostable circuit with a 555.

    The 555 monostable is triggered with a negative pulse so you will have to invert the signal first.

    The LM324 and the 555 work with 9V. What microphone are you using?

    The gain for the non-inverting amplifier is here:
  3. JDR04

    Thread Starter Active Member

    May 5, 2011
    Thanks for that praondevou. I'm using a small cheap electret microphone that I use to use with the computer.

    It makes sense what you are saying about using a 555 in monostable mode, the only thing would be how would I invert the signal. This I am not familiar with. A ny suggestions will be appreciated.

    Would I not have to at least change the value of R1 if I used a 9V battery?

    Oh, and thanks a lot for the link, it will make good reading.
    Thanks again - JDR04