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Thread: Using a Piezo element to control Lasers

  1. #1

    Lightbulb Using a Piezo element to control Lasers

    What I'm thinking is using a Piezo element, mounted to a drum head, in which when the drum is struck it'll cause the element to trigger. (a common use for Piezos in creating "drum triggers")

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

    Then run the signal from the Piezo element into a simple driver circuit that can create more voltage. (which I haven't figured out that circuit yet...help?)

    After the Piezo driver circuit......then what?.....maybe the modulation input of a Laser Driver? Like drlava's Fexmods?:

    http://hacylon.case.edu/ebay/laser_diode/FlexMod01.php

    These will be most likely simple TTL Lasers....how would I wire/setup the Flexmod to be TTL? (The manual doesn't say)

    Could I run the Piezo element's signal straight into the modulation input of the Laser Driver?

    The goal is to have one Laser per drum. When a drum is struck, it'll trigger it's respected Laser. (maybe around 5 drums = 5 lasers or so)

    The effect will probably be simple, maybe a single laser through a Single Fan Diffraction Grating per drum, maybe a motor with a mirror attached spinning for "The Tube" effect per drum, something simple not requiring software.

    Any help with any of the above is ALWAYS very appreciated.

  2. #2

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    Here: http://www.nerdkits.com/videos/sound_meter/

    That should generate a high enough voltage i belive.
    Im thinking about doing this with an arduino board so i can do other stuff like turn diffraction gratings and stuff.

  3. #3

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    DJDoublebass - The piezo you linked is meant to output sound. I'm not sure if it would work well(or even work) for the said application. IMO, you're better off using an optical sensor of some sort. If you play drums, you would know that any object attached on the drumskin would alter the sound or "feel".

    If you're really bent on using a piezo element, they can be found in dollar store lighters(The ones used to light candes). Be warned though; they can generate insane voltages(several hundered) with the slightest compression. I've found that some can generate voltages as high as 40V when tapped gently with a finger...

  4. #4
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    the piezo he linked to has reviews stating it worked for this purpose. It's a pretty cool idea, you will need an amp for the piezo before you connect it to a driver, but with a simple circuit it should work well. Combined with lasers, this could make a decent, sharp effect for drum solos. I'd definitely want to see it

  5. #5
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    use a high input impedance fet opamp in order to get reliable results, or a FET preamp followed by a classic 741 opamp

  6. #6

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    All you want to do is pick up the "hit" on the drum...

    Electret microphones are cheap and you can use a cheap
    microphone Preamp with amplitude control (a Pot) to amplify
    the signal...
    Then feed that into a schmitt trigger IC to grab any pulse over
    the level you set..
    to drown out most background noise... mount it solidly onto the
    drum..

    just my


    Jerry
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  7. #7

    Arrow

    Quote Originally Posted by Snilton View Post
    Here: http://www.nerdkits.com/videos/sound_meter/

    That should generate a high enough voltage i belive.
    Im thinking about doing this with an arduino board so i can do other stuff like turn diffraction gratings and stuff.
    That's pretty close, but it's looking like it requires a computer to program the circuit board. I'm looking for something that's ready to go after assembly. Thanks for your input

    Quote Originally Posted by shrad View Post
    use a high input impedance fet opamp in order to get reliable results, or a FET preamp followed by a classic 741 opamp
    Interesting...it looks like that may work, but I'm not entirely familiar with op amps enough to know how to create a circuit with them from scratch.

    Know of a schematic or assembly off hand that you could point me to?

    Maybe something that can take a tiny signal, (from a Piezo) and generate 0-5 Volts, up to 9.4 Kilo ohms? (got the specs from the manual of Drlava's flexmods):

    http://hacylon.case.edu/ebay/laser_diode/FlexMod01.php

    Thanks for your input

    Quote Originally Posted by lasersbee View Post
    All you want to do is pick up the "hit" on the drum...

    Electret microphones are cheap and you can use a cheap
    microphone Preamp with amplitude control (a Pot) to amplify
    the signal...
    Then feed that into a schmitt trigger IC to grab any pulse over
    the level you set..
    to drown out most background noise... mount it solidly onto the
    drum..

    just my


    Jerry
    That's definitely a thought. I understand the electret mics, then the preamp, (a potentiometer) but I'm not very knowledgable on schmitt trigger IC's. One thing though, is that Piezos are more accurate, and I wouldn't have to worry about tuning out background noise. (there will be a TON of stage noise)

    I do however have a set of drum mics now, and a respectable sound board with direct outs per channel. "impedance balanced: <75 ohm, 0dBu, +21dBu max....." so I don't think that the direct outs will be enough juice.

    I'd have to change whatever sensor that I use every time I change heads on my drums...3 tom heads about once every few weeks, and the snare head more frequently. (kick drum the least frequent) Piezos are very cheap. It would only cost another $0.75 per head to change the Piezos.

    Would something like a relay work? Something like this?:

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

    Or would a Piezo create just not enough voltage?

    Thanks for everybody's efforts. I very much appreciate it.

  8. #8
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    this circuit would do the trick:

    http://www.sonelec-musique.com/image...n_meca_001.gif

    you might drop the Q1 stage and directly take the output of the second opamp to drive your trigger input... there are sensitivity and level pots

  9. #9
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    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!

  10. #10
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    the schematic I linked is relatively easy to wire on a piece of proto board and has sensitivity and level settings, so it would be applicable to any instrument, even trumpets or harmonicas

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