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Thread: Using a Piezo element to control Lasers

  1. #11
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    Lightbulb

    Quote Originally Posted by T0mmm View Post
    something like this velleman sound-to-light kit is already designed for you and runs off a 9v battery that has an electret microphone in it.
    you could perhaps run the power to the LED's to the modulation of the laser driver..

    The only potential problem is that you might have to put the microphone in a tube of some sort so that it only 'listens' to the diaphragm of the one drum

    http://www.vellemanusa.com/us/enu/pr...iew/?id=350678

    you can probably buy the kits more locally through radioshack or even ebay

    the bass drum would be easier to do, all you'd need is a little microswitch on the foot pedal

    Interesting project though!
    Hmmm...I wonder if the Microphone on that kit could be swapped for a piezo? Since the mic has 3 connections, one probably being power, it might not work.

    Thanks for everyones help on this, I'm really looking forward to figuring this out.

    I started to search for kits after realizing that they existed and found this color organ circuit:

    http://www.kitsusa.net/phpstore/html...g-kit-551.html

    This mic used is a "crystal microphone"....or really a Piezo....so I know that I could just swap it for a Piezo. The LEDs used could be the signal to the laser driver. I'd have to see how the circuit reacts and which LEDs light up when etc etc.

    I found this preamp too:

    http://www.kitsusa.net/phpstore/html...LIFIER-28.html

    I wish that they had more specs on it, so then I wouldn't have to assume that it would put out enough juice to trigger the laser driver's modulation input.

    Any opinions? Or ideas?

    Thanks again for everyone's help.

  2. #12
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    Default

    After looking at the YouTube video that "Snilton" linked to...
    I saw another video that shows the raw output of a Piezo
    disk driving a Green LED.

    http://www.youtube.com/watch?v=Xuw9f...eature=related

    I now agree that perhaps the Piezo route would be easier than a
    Microphone and preamp to get a usable signal..
    Very simply... you could take the output of the Piezo and run the
    input LED of an Opto Isolator like a 4N26 or even a Triac output
    Opto Isolator like MOC3011... then control what you want with
    the output of the Opto Isolator of your choice...


    Jerry
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  3. #13
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    Default

    a piezzo will not power a LED which will easily consume 25mA, as the piezzo only outputs some microamps at max... true that you will perhaps reach some tens of volts, but that will not work

    trust that one, the circuit I've given will do the trick with a small alarm clock or toy piezzo, which you can tape under your membranes

    you just have to find someone to engrave the board for you if it's not possible for you to do it

    I can draw you a board on eagle if you want, it's quite easy, SMD or through hole, as you wish

  4. #14
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    Default

    Quote Originally Posted by shrad View Post
    a piezzo will not power a LED which will easily consume 25mA, as the piezzo only outputs some microamps at max... true that you will perhaps reach some tens of volts, but that will not work

    trust that one, the circuit I've given will do the trick with a small alarm clock or toy piezzo, which you can tape under your membranes

    you just have to find someone to engrave the board for you if it's not possible for you to do it

    I can draw you a board on eagle if you want, it's quite easy, SMD or through hole, as you wish
    Hey shrad...

    Did you not see the Video I linked to... It clearly shows 1 Green LED flashing
    in time with the tapping on a Piezo buzzer disk... I see no other
    components...
    The OP wants to detect the beats of the drum... and this idea seems to work...
    Am I missing something...

    BTW... your circuit looks like it will pick up all sound in the piezo's range with
    a lot more circuitry... to produce the same single shot response..

    The 1st stage is an amplifier and the 2nd stage is an average peak detector
    comparator..

    But I suppose either circuit will give you some results...


    Jerry
    Last edited by lasersbee; 10-12-2009 at 02:20.
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  5. #15
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    Default

    I'm not an expert with diode drivers or anything, but wouldn't you need some sort of voltage/current limiting circuitry before feeding a piezo straight into the +mod of the driver? surely if you really slammed that piezo it would make more than 5v, which some drivers might not be designed to cope with.
    Just a thought

  6. #16
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    Lightbulb

    What about a relay like this? :::

    http://www.allelectronics.com/make-a...RELAY/-/1.html

    That way the relay would deliver consistent voltage each time it's triggered.

  7. #17
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    A relay is very slow to react and output a signal compared to an electronic switch like a transistor...


    Jerry
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  8. #18
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    plus you'd need quite a big piezo to power up the solenoid insode it, they draw a relatively large amount of current

  9. #19
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    yup, sorry for the assumption that a piezzo couldn't drive a LED, I missed the word "correctly" in the sentence

    in fact the circuit I mentioned picks all the noise from the piezzo, amplifies it by a scalable factor, and then triggers on a scalable level

    the output being 0V or 5V low current from the opamp, it is best suited to attack the input of a modulation input or DMX input board without damaging it, and the scalable gain and treshold will allow to adapt it to any instrument, be it a trumpet or a giant tam-tam

  10. #20
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    Default

    Quote Originally Posted by lasersbee View Post
    I now agree that perhaps the Piezo route would be easier than a
    Microphone and preamp to get a usable signal..
    Very simply... you could take the output of the Piezo and run the
    input LED of an Opto Isolator like a 4N26 or even a Triac output
    Opto Isolator like MOC3011... then control what you want with
    the output of the Opto Isolator of your choice...


    Jerry

    So would the wiring diagram look something like this?

    (please correct me if it's wrong)
    Attached Thumbnails Attached Thumbnails Piezo Wiring Diagram.bmp  


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