Acoustic energy harvesting

[mnsman]

What is the best way to harvest the energy of sound waves?

Can an mechanical resonance circuit be built to do this?

Perhaps a resonant cavity tube with a piezoelectric device at the end of the tube will work? Or something similar?

Or something I can't imagine?

Thought exercise
Let's say for instance I gave you the job of setting up a sound source in a room. It creates a sum total of 120db audio output with many strong harmonics that range from 1KHz to over 15KHz at 1kHz intervals. There's one twist though. I say to you I want you to recover all of the sound energy this device puts out and convert it to useable electrical energy to be used to power the room's light. You say to me- Convert all? All is a tall task and it's probably impossible. I agree and allow you to recover only what you can.

How much can you recover and what is your method?

At the moment this is only a thought exercise. BUT I do happen to have a sound source that meets the above criteria. It's my pulsed dc motor. I already have a thread talking about that. In this thread I would like input on the sound energy harvesting and conversion aspect of my project.

The sound created by my device is a byproduct of the bearings and coil. Let's assume that both byproducts are unavoidable. Given that... The resultant sound represents energy coming from the system that is currently considered a loss. Naturally I want to harvest the loss, convert it to useable electrical energy and reinvest it.

This is quite new to me but I have made a few mediocre attempts to do this using piezoelectric devices simply taped to the inside of the motor's enclosure. Videos of this can be seen here: First motor piezo test 12-4-11 - YouTube
and here: Second piezo test 12-4-11 and new record 68,000 rpm - YouTube

Video of Db measurement (cheap meter rated only up to 8kz frequency range): P-Motor update and decibel test 120db 12-14-11 - YouTube

Video of spectrum analysis (at the mercy of the camera's microphone's frequency response): Spectrum analysis of audio output at max speed and max piezo output - YouTube

If your solution is a cavity then what are the dimensions and material?
Can you demonstrate the formulas required to properly calculate the cavities dimensions?

Bear in mind that the optimum rpm of the motor has not been established. It has run up to 76,400 rpm which is a frequency of 76,400/60 = 1266.66...Hz. To keep it simple let's work with 1KHz (60,000 rpm).

What are your thoughts?

Jim

[Cherryman]

edit dubbel post

[Cherryman]

A microphone and a speaker are in basics the same thing.

When the membrane (coil) of a microphone resonates to the sound it creates a tiny bit of electric energy passing a magnet.

And a loudspeaker vice versa.

So in basic you should find a speaker / microphone, optimized to your frequency and dB level, and you will find a (tiny) electrical force at the wires when running your engine.
You have high pitch, so maybe high voltage is a direction, instead of amps.

Encapsulating the soundsource and directing it to a microphone could deliver more power ( as a guitar base)
But having multiple microphones could also work better, because one microphone does not steal from the other.

I think i did read somewhere that there has been a study to use sound "generators" for the noise of Niagara falls, you might wanna look that up.

Nice engine! Btw.

Peace

[OrionLightShip]

Jim, the first thing that pops into my mind is using a parabolic dish to concentrate the sound waves onto a piezo crystal to increase the efficiency.

Way back when, I used to have a ten foot satellite dish. You could stand at the focal point and hear neighbors talking.

Then there is the cavitation steam generator but that doesn't involve catching the sound from the bearings and stand. Might be quite efficient at 60,000 rpm though!

Orion

[mnsman]

A microphone and a speaker are in basics the same thing.

When the membrane (coil) of a microphone resonates to the sound it creates a tiny bit of electric energy passing a magnet.

And a loudspeaker vice versa.

So in basic you should find a speaker / microphone, optimized to your frequency and dB level, and you will find a (tiny) electrical force at the wires when running your engine.
You have high pitch, so maybe high voltage is a direction, instead of amps.

Encapsulating the soundsource and directing it to a microphone could deliver more power ( as a guitar base)
But having multiple microphones could also work better, because one microphone does not steal from the other.

I think i did read somewhere that there has been a study to use sound "generators" for the noise of Niagara falls, you might wanna look that up.

Nice engine! Btw.

Peace

Thanks for your input Cherryman. I'm still in the early stages of development. With regard to this aspect of my project, first I must find the speed at which I have peak audio output and determine that frequency. I will be performing another spectrum analysis in order to achieve that. It has been suggested to me that a speaker may work but I have as of yet tried one. I already have a box enclosure for the device with a removable front panel. That opening could serve as a point to attach a waveguide in order to direct the energy as you suggested.

I have to look into the Niagra sound generator. If you happen to remember where you came across that let me know. That's interesting.

[mnsman]

Jim, the first thing that pops into my mind is using a parabolic dish to concentrate the sound waves onto a piezo crystal to increase the efficiency.

Way back when, I used to have a ten foot satellite dish. You could stand at the focal point and hear neighbors talking.

Then there is the cavitation steam generator but that doesn't involve catching the sound from the bearings and stand. Might be quite efficient at 60,000 rpm though!

Orion

Orion,

Yes- just like they do at football games too. I remember seeing guys on the sideline with small parabolic dishes fitted with microphones. Probably to spy on the other team. lol Very good observation and interesting idea. It's now filed in the noggin for future testing. I must re-examine the cavitation steam generator. I remember someone with a device that worked on that principle. Can't remember the details except it was supposed to be super efficient and possibly OU.

Thanks again for your input.

[mnsman]

Read "Universal laws" by John Earnst Worrell Keeely. He is the inventor of several musical and harmony machines. He has many patents and built several machines for his investors, who took him to court and sued him for the machines. Almost all great inventors have gone down this road. His sympathetic vibration machines were awesome, if we only could figure out all the details. Unfortunately he tore up all his notes when they sued him and, as far as I know never rewrote them, or if he did, someone acquired them and or secreted them. Good Luck. stealth

Stealth,

I've heard of Keely but never have investigated his work. He sounds like a typical ridiculed inventor who takes his secrets to the grave. I see the book is authored or edited by Dale Pond and I will put it on my long to do list. It's available for download at Universal Laws Never Before Revealed Keelys Secrets to Understanding the Science of Sympathetic Vibration

Thanks for the suggestion and keep them coming. -jim

[willy96]

nice!

intresting thred you have here ...

this is what i have come up with

no motion peroid this is how it is done ... a long time ago ..
match your coil to the impeadiance of the amp..

make your coil a rotating transformer ..
then do this to it ..

it uses my kick! rizes to resonance then heterodynes 3 freqs.. from a SINGLE FLICK OF THE SWITCH
H0H 808 AUDIO ! MAG!C MY MOVIE ONLY ONE - YouTube


MERRY CHRISTMAS..

santa,

ps be carefull .. i would encase the coil and core in lexan ... just incase she blows ...
were just ringggging a wine glass here thats .. all ..
move along peoples .. high speed into the new year !


me and cenderella put it all togather we can drive it home with 1 head light !
The Wallflowers - One Headlight - YouTube

[kcarring]

I wonder if when tubes feedback, and begin to wail... like, very loudly in a very high powered guitar amp... from an energy point of view, I wonder if you are "paying for that"... if the amp draw goes up, or... if that increased energy is a product of resonance. Just a thought.

[mnsman]

I wonder if when tubes feedback, and begin to wail... like, very loudly in a very high powered guitar amp... from an energy point of view, I wonder if you are "paying for that"... if the amp draw goes up, or... if that increased energy is a product of resonance. Just a thought.

I think the coil is acting like a speaker. A very loud speaker. The square wave input is full of the harmonics of the driving frequency. I don't think there is any resonance involved with exception of any object in close proximity to the device that has it's resonant frequency at one of the harmonics. In this sense I think it is drawing the amount of current it should with the given input voltage. Feedback is another story. With the audio vibrating everything that surrounds it there must be feedback to some degree. These are just my opinions. Yours are as good as mine and I thank you for them.

[mnsman]

Update

Today I made the first step toward determining the size of a resonant cavity. I have the material to make it out of pvc. I prefer glass but this is a proof of concept build and pvc is something I can work with. It will be a 2" pvc pipe with a pvc cap on one end. A 1khz piezoelectric speaker will be secured to the inside of the cap. At the other end of the pipe I will reduce it in several steps to a 3/4" opening. It will be much like the shape of a pop bottle. The exact length of the 2" pipe is still in question but it looks like the entire device will be very short. I've had help with the calculation and I await the result.

The P-Motor project is in redesign mode right now because of continual failures of power mosfets. Hopefully I am designing a better power on and driver circuit with more protection for the power mosfet drivers. I am adding a micro controller for pulse timing and duration which will improve efficiency and allow better speed control. The project is at a halt until I build the new circuit and find an appropriate controller. While my career has been in electronics it has been in repair and not in design so suggestions regarding the circuit design are welcome. Stop by and give your input on the proposed circuit. http://www.energeticforum.com/renewa...tml#post172932

I know there are some people out there on this forum that can light my hypothetical light bulb. There are people that are running florescent bulbs with a scant amount of input power and probably can light a bulb with as little input as I have already harvested with minimal effort. I won't name them but I know the work of a few of them and I know they can do it. If you are one of these people please consider giving your input. Once done I'll have to up the ante to two bulbs.

Jim

[mnsman]

Gone fishing

[mnsman]

Newest Vid

P-Motor update 01-06-12 Sonic energy harvesting - YouTube

Lit two led's with one piezoelectric speaker.

I can also hook bridge and cap up to single piezo output and generate up to 2v dc with aprox. 17Vdc 600mA input to motor. This can be improved upon. I have only started. Thanks for the help.

6Vdc output
P-Motor update 01-08-12 Sonic energy harvesting - YouTube

I know, I know... If I'm gonna quit then quit. Here's one more for the "curious".
35Vdc output 80Vpp
P-Motor update 1-9-12 Sonic energy harvesting - Improved resonator - YouTube


Good bye. Unsubscribing from my own thread.

[mnsman]

Found a new home

Project summary and updates can be found at International Alternative Energy Center - P-Motor project - Powered by ForumCo.com - The Forum Company

Many updates since last posting here.