Here is how to make a practical example that might produce enough energy to charge a small battery.

Get about 10,000 small (50cm) speakers. Connect them in a series-parallel arrangement to produce several volts at 120dB sound level. feed a bridge rectifier with the output to convert to DC.

Now place it right beside the take-off end of a runway at the local airport. Each time a passenger or cargo jet takes off it will add a little charge to the battery.

Bob

 

This sort of energy harvesting is more like energy stealing. And that could have some utility in cases where you don’t care that it is going to cost more to do the primary thing you are stealing from—either because you are a sociopath or because you are the one paying for the primary energy source and need some sort of wireless power for a tiny function.

If you were to use some kind of acoustical power conversion at, say, Niagara Falls, you might call that “hydroelectric power generation“ and hey, maybe that could actually be useful for very small, very local application.

 

do you believe sound can be converted to electricity?

Yes, we all do. To prove it to yourself just look at the output of any microphone on an oscilloscope. But as has been pointed out already, the amount is exceedingly small.

 

Yes, we all do. To prove it to yourself just look at the output of any microphone on an oscilloscope. But as has been pointed out already, the amount is exceedingly small.

That's my concern. The microphones are not designed for power generation. Trying to use them for the same is simply a leap of faith. The microphones, however, do show the possibility of this theory.

 

Yes it does reduce the volume if it does any work, like converting the mechanical energy to something else (e.g. heat, electricity, &c). YOu can’t double dip. Whatever portion of the sound‘s energy is used to make electricity is no Longer available to move the parts of the ears of the watcher that transduce the sound’s energy into the perception of sound.

TANSTAAFL

Hmm... but like I stated, this is not the scope. And we also need to consider that there may be ambient noises such as that from the fan, or the kids talking or the vibration of an air-conditioner. The reduction in the TVs volume, if there is, will be very minimal. But this is not the scope. How about placing the acoustic converters beside generators. These things produce a lot of non-useful sound.

 

That's my concern. The microphones are not designed for power generation. Trying to use them for the same is simply a leap of faith. The microphones, however, do show the possibility of this theory.

Are you intentionally ignoring the basic information about the energy available in the sound? It's not the transducer that's the problem, it's the fact that there is almost no energy to work with. You can't get something from nothing and anything you do take will need to be replaced if the source is trying to do some other work.

This ignores the other troubles of charging batteries which is an electrochemical process with losses and limits completely incompatible with the micro power available in ambient acoustical energy.

You are not facing some sort of clever design challenge, you are up against fundamental physical limits and you can't design those away.

This is not a fruitful direction and though I have tried to explain this to you your naive certainty that you've spotted something everyone else has missed makes communication impossible. Good luck, I'm done.

 

Are you intentionally ignoring the basic information about the energy available in the sound? It's not the transducer that's the problem, it's the fact that there is almost no energy to work with. You can't get something from nothing and anything you do take will need to be replaced if the source is trying to do some other work.

This ignores the other troubles of charging batteries which is an electrochemical process with losses and limits completely incompatible with the micro power available in ambient acoustical energy.

You are not facing some sort of clever design challenge, you are up against fundamental physical limits and you can't design those away.

This is not a fruitful direction and though I have tried to explain this to you your naive certainty that you've spotted something everyone else has missed makes communication impossible. Good luck, I'm done.

Thanks Yaakov. I appreciate all of your guidance.

 

You want to charge a battery or a capacitor. They store DC.
But a microphone produces AC that must be rectified into DC. The voltage from a microphone is much too small tor a rectifier but maybe a few hundred microphones can be connected together and a loud sound can make enough voltage to be rectified.
The rectified output current will be extremely low.

 

The trouble is here that any microphone currently available has been designed for a specific frequency response and absence of distortion. Efficiency was not even considered. Some ribbon mics have output is the region of microvolts.
If this project is going anywhere then the TS should concentrate his efforts in finding an efficient way of converting sound (or small random movements of air) to electricity.
If successful, it would be very useful for power generation in situations where airflow is too random or turbulent for a wind turbine, such as close to buildings.
Even for a domestic situation, I suspect that movements of air from opening doors, people walking about etc. would provide a much better source of energy than stealing it from the audio.
Having produced an AC signal of sufficient amplitude, then getting it to charge a battery is trivial by comparison.

 

Here is how to make a practical example that might produce enough energy to charge a small battery.

Get about 10,000 small (50cm) speakers. Connect them in a series-parallel arrangement to produce several volts at 120dB sound level. feed a bridge rectifier with the output to convert to DC.

Now place it right beside the take-off end of a runway at the local airport. Each time a passenger or cargo jet takes off it will add a little charge to the battery.

Bob

What's in your hi-fi if you think a 50cm speaker is small? The Fane Colossus 18's in mine are only 45cm!

 

It’s being used to charge a battery (no matter how small)

You can not use an amplifier because that would use more power than you would generate. To charge a battery, you need a voltage higher than the terminal voltage of the battery. To convert sound into enough energy to do that, you would have to make your own device. It would need a very large diaphragm, and to avoid transformer losses, it would need many turns on the moving coil. The signal would need to be converted to DC with a bridge rectifier using low forward voltage diodes, and a good quality capacitor to smooth the output. It would hardly be worth the effort though because it would produce very little power.

 

hi,
I would say just heating up his soldering iron to make the project would use more power that he ever likely to produce, using the sound idea.!!!
E

 

In theory you may be correct. But I prefer atferrari's signature:

In theory, there is no difference between theory and practice. In practice, however, there is.

 

If you want to experiment harvesting from ultra-low energy sources, try LTC3108.

https://www.analog.com/media/en/technical-documentation/data-sheets/LTC3108.pdf

https://www.digikey.com/reference-designs/en/ac-dc-and-dc-dc-conversion/dc-dc-smps-multi-output/1590