Using microphones to convert sound into electricity ?

[Deviatore]

hey guys, umm i am going to take part in a science exhibition and was thinking of a good project to work on till i found this thread here in this forums :-

 

http://hypography.com/forums/science-projects-and-homework/2531-sound-energy-to-electricity.html

 

Since i am not a genius in science, i tried to search google to find out something but failed.

So if anyone knows a site or any article that explains in a little step by step then will you please post it in here ?

[Boerseun]

Well, a machine to convert sound energy into electricity is exactly what a microphone is.

 

Essentially, you have a flat piece of light, studry material (like cardboard) with a coil of wire attached to it. This coil is surrounded by a magnet which is on a different mounting - it does not move with the coil - or there should be a very soft suspension between the two, at least. So soundwaves make the cardboard vibrate, and this in turn causes the coil to move through the magnet's magnetic field. This causes an electric current to be induced into the coil, which is the electricity you're looking for.

 

Reversing the process (i.e. supplying electricity into the coil) will make the cardboard move as the current acts against the magnetic field, and then you'll have a speaker. A speaker and a microphone is essentially the same device - the one just works in reverse.

 

As an example, you can take one of your hi-fi speakers and connect its wires to the normal male microphone jack, and plug it into the microphone slot in your hi-fi. If you switch the Mic button on and talk into the speaker, you should hear yourself talking from the remaining speaker. But it probably would be cheaper to just take my word for it.

 

So - what are you battling with? Schematics? Diagrams? There are plenty of them on the web. If you're battling with something, feel free to ask.

[Deviatore]

i didnt find any diagram on the net of it so i thought, that will i have to just connect the microphone to a up-transformer which will increase the electric current and then connect it with a very very small bulb.

 

So can i do that or will i have to connect in between something more ?

[Boerseun]

What you're proposing is exactly how an amplifier works. It gets an inducted current from the microphone, and then amplify it (basically the step-up transformer you have in mind) and then serves the amplified current to the speaker. In your design, you're merely swapping the speaker for a lightbulb.

 

You should keep in mind, though, that the input received from the microphone is very small. Hifi amplifiers are powered, and aren't merely using the mike input as the input voltage in a straight-forward step-up transformer (which is just two coils of differing coil counts looped around each other). Which means if you have to use an external power source (for amplification) it kinda blows your demonstration of drawing energy from sound out of the water.

 

So you probably want a straight-forward Mike-Stepup-Lighbulb scenario.

 

I suppose if you have a big enough mike with enough coils inside a strong enough magnet then you could conceivable light up an LED. I doubt if you'll get anywhere with an incandescent bulb. But yes, it might work.

[nigam.malay]

hi!!!

i was also working on similar project...i would like to know that weather the low amount of energy production is due to the losses inn conversion or it is the only amount of energy that sound waves hold...??

[Turtle]

hi!!!

i was also working on similar project...i would like to know that weather the low amount of energy production is due to the losses inn conversion or it is the only amount of energy that sound waves hold...??

 

some of both. the intial energy of the sound wave is the maximum that could be "transduced", and the specifics of the transducer construction reduce it from there. for example, if the membrane in a "moving coil" microphone were stiffer, then there would be greater losses changing the sound energy to electricity because there would be less movement in the coil.

 

 

Microphones Tutorial | Acoustics, Audio and Video | University of Salford - A Greater Manchester University

 

if there's any chance of lighting a small bulb or led directly from a sound-driven transducer, i suspect the "microphone" ought to be as large a speaker as possible and the sound as loud & volumnous as possible. :coffee_n_pc:

[nigam.malay]

hey thanks.....

may be i can use some low frequency and high amplitude vibrations(such as the unbalanced force of ic engine or the hammer blow phenomenon in diesel locomotives) to get better results......and can piezoelectric crystal be of some help????

[Turtle]

hey thanks.....

may be i can use some low frequency and high amplitude vibrations(such as the unbalanced force of ic engine or the hammer blow phenomenon in diesel locomotives) to get better results......and can piezoelectric crystal be of some help????

 

sounds reasonable on the sound source. i meant to post this for you earlier.

 

In practical use, speakers are sometimes used as microphones in applications where high quality and sensitivity are not needed such as intercoms, walkie-talkies or Xbox Live chat peripherals.

 

However, there is at least one other practical application of this principle: Using a medium-size woofer placed closely in front of a "kick" (bass drum) in a drum set to act as a microphone. The use of relatively large speakers to transduce low frequency sound sources, especially in music production, is becoming fairly common. A product example of this type of device is the Yamaha Subkick, a 12-inch (300 mm) woofer used in front of kick drums. Since a relatively massive membrane is unable to transduce high frequencies, placing a speaker in front of a kick drum is often ideal for reducing cymbal and snare bleed into the kick drum sound.

 

Microphone - Wikipedia, the free encyclopedia

(there's a section in the article on piezo-electric microphones as well as many other types. :D )

 

i do think the piezoelectric microphone would be too low power to light a bulb without amplification. perhaps a bulb isn't the way to go since you just want to demonstrate the principle of sound-to-electricity; in that case, i'd try a volt-meter and call any needle deflection proof of concept.