Sound Activated LEDs

Discussion in 'General Electronics Chat' started by fr0zt, May 17, 2006.

  1. fr0zt

    Thread Starter New Member

    May 17, 2006
    3
    0
    Hey, I'm just trying to create a disco type lighting system of sound activated LEDs. The functionality of this circuit should be the following:

    1 - LEDs can flash to the input from a microphone
    2 - The sensitivity should be adjustable
    3 - Another mode should be present allowing LEDs to flash on/off at a certain frequency
    4 - This frequency should be adjustable
    5 - A switch should be present to switch between the two modes

    I am wondering if the following schematic will complete this purpuse and if it could be improved upon at all. Thanks
     
  2. Murod

    Active Member

    Dec 24, 2005
    30
    0
    1 - LEDs can flash to  the input from a microphone
    >>The signal from microphone is amplified by first opamp, then rectified and filtered by D1, C1 and R5 to get the envelope of the signal (short term amplitude average). The envelope then compared to the voltage level  of pin 6 of the second opamp (comparator).

    If higher then second opamp output = high (close to Vcc),
    in adjusting sensitivity (1st mode), this will drive the mosfet to turn the led on. In disco mode (2nd mode) this will activate the astable multivibrator (3rd IC block) by holding the reset pin to Vcc.

    If lower then second opamp output= low (close to ground),
    in adjusting sensitivity, this will drive the mosfet to turn the led off. In disco mode, this will deactivate the astable multivibrator by holding the reset pin to ground.


    2 - The sensitivity should be adjustable
    >> done by adjusting voltage reference of comparator (second opamp)

    3 - Another mode should be present allowing LEDs to flash on/off at a certain frequency
    >> the frequency is the astable multivibrator's running frequency.

    4 - This frequency should be adjustable
    >> done by r10 to adjhust charging time of C2.

    5 - A switch should be present to switch between the two modes
    >> done by SW to choose the source of mosfet driver, whether from comparator or from monostable multivibrator. The 1st mode seems just for adjusting the sensitivity to get an appropriate level, not for normal operation, but it's OK for normal operation too.

    I am wondering if the following schematic will complete this purpuse and if it could be improved upon at all. Thanks
    >> I hope my explanation would be helpful for you. About comparator, astable mutivibrator, and monostable multivibrator please consult other references, I can't explain everything for you.



    Best Regard,

    Hasan Murod.
     
  3. Murod

    Active Member

    Dec 24, 2005
    30
    0
    1 - LEDs can flash to the input from a microphone
    >>The signal from microphone is amplified by first opamp, then rectified and filtered by D1, C1 and R5 to get the envelope of the signal (short term amplitude average). The envelope then compared to the voltage level of pin 6 of the second opamp (comparator).

    If higher then second opamp output = high (close to Vcc),
    in adjusting sensitivity (1st mode), this will drive the mosfet to turn the led on. In disco mode (2nd mode) this will activate the astable multivibrator (3rd IC block) by holding the reset pin to Vcc.

    If lower then second opamp output= low (close to ground),
    in adjusting sensitivity, this will drive the mosfet to turn the led off. In disco mode, this will deactivate the astable multivibrator by holding the reset pin to ground.


    2 - The sensitivity should be adjustable
    >> done by adjusting voltage reference of comparator (second opamp)

    3 - Another mode should be present allowing LEDs to flash on/off at a certain frequency
    >> the frequency is the astable multivibrator's running frequency.

    4 - This frequency should be adjustable
    >> done by r10 to adjhust charging time of C2.

    5 - A switch should be present to switch between the two modes
    >> done by SW to choose the source of mosfet driver, whether from comparator or from monostable multivibrator. The 1st mode seems just for adjusting the sensitivity to get an appropriate level, not for normal operation, but it's OK for normal operation too.

    I am wondering if the following schematic will complete this purpuse and if it could be improved upon at all. Thanks
    >> I hope my explanation would be helpful for you. About comparator, astable mutivibrator, and monostable multivibrator please consult other references, I can't explain everything for you.


    Best Regard,

    Hasan Murod.
     
  4. fr0zt

    Thread Starter New Member

    May 17, 2006
    3
    0
    Thanks for the help, so will the above schematic work to serve this purpose? Also, what type of capacitors and what type of resistors (how many watts). I want this to be able to drive quite a bit.
     
  5. Murod

    Active Member

    Dec 24, 2005
    30
    0
    Yes, the schematic will work to serve that purpose. You can use ceramic / polyester capacitor for all acapacitors below 1 uF, and 16 volt (or more) electrolitic capacitor for all capacitors >=1 uF. You can use 1/4 watt carbon film resistor.

    Hasan Murod.
     
  6. fr0zt

    Thread Starter New Member

    May 17, 2006
    3
    0
    Alright, so I should just use electrolitic capacitors, because all values are equal to or over 1uF? Would ceramic/polyester capacitors be alright for the 1uF values? Also, how many amps will this drive? Just to make sure I don't blow it out. Thanks
     
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