need help for my school project

Discussion in 'The Projects Forum' started by jhaydelafuente, Nov 28, 2013.

  1. jhaydelafuente

    Thread Starter New Member

    Nov 28, 2013
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    Good day everyone, I am an electrical engineering student from Polytechnic University of the Philippines. I have a project study on converting sound energy to electrical energy. I have read different articles regarding this topic and I think that reading those articles isn't enough.

    I am looking for possible circuit which i will be using and most especially alternative components in building this project beacuse buying piezoelectric film will cost me alot.

    Anyone with a big heart kindly help me on my project. Any reply in this thread is greatly appreciated.
     
  2. WBahn

    Moderator

    Mar 31, 2012
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    It sounds like you are basically saying, "I couldn't find a finished project in any of the articles I read. Could someone do my project for me?"

    You need to be a LOT more specific regarding what you are trying to accomplish. A microphone converts sound energy to electrical energy, but I suspect you are looking for something more specific than that. But, not being a mind reader, I have no idea what.
     
  3. jhaydelafuente

    Thread Starter New Member

    Nov 28, 2013
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    LOL :) I'm not not looking for a finished product :D I am just looking for another possible circuit which I will compare with the circuits I'd found. And also I am looking for a possible alternative component to replace piezoelectric film because I have found an article that gives almost a finish product, but the components will be bought to them.
     
  4. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Have you done research to see just how small the amount of energy per square metre you can "harvest" from sound is?

    And allow for the fact that with cheap construction etc the efficiency of a home made setup will be extremely low.

    Probably hundreds, maybe thousands of times less energy out than you would get from the same area of solar panels and the solar panels might be cheaper per area.
     
  5. WBahn

    Moderator

    Mar 31, 2012
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    Let me say this again: WE ARE NOT MIND READERS!

    You want someone to give you a circuit (which sounds an awful lot like someone doing your work for you) to compare to circuits you've found. Yet, you won't tell us just what this circuit is supposed to do or what these circuits are that it is supposed to be comparable to.

    Based on what you've given us so far, look at a microphone circuit.
     
  6. jhaydelafuente

    Thread Starter New Member

    Nov 28, 2013
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    What am I doing is a project study which covers converting sound energy (specifically noise) to electrical energy. My main goal in here is to prove that this concept is attainable. I didn't have to ligth a whole house (I am just a student assigned with a project study, I'm not an inventor or what). All I have to do is to make a small prototype (consists of 3-5 LED).

    Which simply means that I don't need a large scale output.. All I have to do is to gather energy from sound, convert it to electrical energy, store it in a rechargable dc supply and light up 3-5 LED.

    I AM JUST FINDING ALTERNATIVE COMPONENTS IN REPLACEMENT TO PIEZOELECTRIC FILM. MICROPHONE IS ONE, IS THERE ANY OTHER COMPONENTS I CAN USE?
     
  7. strantor

    AAC Fanatic!

    Oct 3, 2010
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    I'm thinking that the only way you're going to harvest enough energy to power 5 LEDs is to mechanically couple an unpowered subwoofer (your LED power source) with a giant magnet on it face-to-face to a subwoofer which is powered by at least a 1KW amp, playing SPL competition tracks on loop.

    I could be totally wrong about that, but if it were my project, that is where I would start; I would have no faith that a lesser approach is worth investing in, unless I had seen one work, which I haven't (but I haven't looked either)
     
  8. WBahn

    Moderator

    Mar 31, 2012
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    Okay, we're starting to tease some sort of specs out of you. So we are talking about lighting up 3-5 LEDs. But for how long? Continuously? For one second a day?

    Look at these tennis shoes that little kids wear that take the energy of their footsteps to briefly power some flashing LEDs.
     
  9. #12

    Expert

    Nov 30, 2010
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    I think, try doing the math. Assume an average noise level of maybe 100 db SPL and calculate the amount of energy is passing through one square meter. Then you will know whether you could light even one LED if your gathering machine was 100% efficient.

    If I'm reading my book* correctly, that would be about 10 ^-11 watt seconds per second per square meter.

    *Sound System Engineering by Don and Carolyn Davis, Howard Sams, 1975
     
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  10. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    That sounds reasonable, microwatts per square metre assuming extremely high sound levels and 100% efficiency converting the sound to electric power.

    I would propose a simple test; get a 12" woofer etc, attach to a load resistor and place it in front of your traffic noise so the 12" woofer acts as an efficient dynamic microphone (converts sound to electrical energy).

    Then any oscilloscope should show the amount of electrical power you are generating, by viewing the waveform on the load resistor and doing a simple calc.
     
  11. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    100dB = 10mW/sq metre. So even with a 1sq m parabolic dish with a 100% efficient mic at the focus you would be harvesting only 10mW. That is not going to light many LEDs :(.
     
  12. wayneh

    Expert

    Sep 9, 2010
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    Under what circumstances? If you can use the thunder of a waterfall or the roar of jet engines on the tarmac at an airport, you have a chance. If you have to relay on bat farts in a cave, you have no chance.

    Anything you design will need to optimized for the frequency of the source energy. A device that can harvest at 5kHz is unlikely to work as well at 50Hz.

    By "noise", do you mean broad spectrum? You'll have to avoid excluding any of the frequencies, as these will carry a portion of the available energy, which is already vanishingly small.
     
  13. #12

    Expert

    Nov 30, 2010
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    One real test result is worth a dozen theoretical discussions.
     
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