digital amplifier

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Hi

does anyone come across an basic digital amplifier, the one that can make some noise :D

Thanks

Zhuhua Wu - Electronic Engineering Student

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Quote:
one that can make some noise
Do you mean when they explode? :roll:

Or are you after a class D audio amplifier?

..and moving to general electronics..

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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thanks guys

Class D power amplifier might be something I am looking for :)

Zhuhua Wu - Electronic Engineering Student

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What is your transducer? A conventional speaker? A piezo "vibrator" (makes sound with simple applied voltage)? A piezo annunciator (takes an excitation that pulses at the tone frequency)? A cellphone vibrator?

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

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If this is just so an AVR can make some noise from a small 8ohm speaker you might want to look at the LM386 which is very popular as it runs easily from the same 5V supply the AVR may be using. For example:

http://www.electronicecircuits.c...
http://www.hobby-hour.com/electr...
(and more if you google "LM386")

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If indeed all you want to do is make noise using a speaker, then a simple NPN transistor would work as well.

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

"The critical shortage here is not stuff, but time." - Johan Ekdahl

 

"Step N is required before you can do step N+1!" - ka7ehk

 

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

 

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user

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so here is what I want to do:
sound/noise canceling.

why?
my "friendly" neighbor from up stair love loud music at night, say after 11pm to 1-2 am at night, all my effort try to talk to them didn't work.

so I am thinking I am a EE student, I may be able to built something to reduce/cancel out the music?

So I did some search, and I found two solution (electrically):
1. noise cancelling circuit, or
2. EMP gun.

and I go for the first solution :)

Zhuhua Wu - Electronic Engineering Student

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The TDA8920 boards on eBay are a great deal, 200 watts for about $20. They require a split supply.

http://www.ebay.ca/itm/YJ-Mini-1...

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I believe it will need to invert the output signal to make a sound suspension device, and buying one will take out all the fun of building one ;)

Zhuhua Wu - Electronic Engineering Student

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I think 'masking' is a plan. Get one of those clock radios that has environmental sounds like a babbling brook, waves and seagulls, crickets in the forest, and maybe some earplugs.

Imagecraft compiler user

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Quote:
I go for the first solution
It will NOT work, the second solution might or even getting your friendly police force involved.

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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Something subtle might work. Ever see those seat shakers they use in theaters and simulators? Put those on the ceiling and get a Big Fine Amp and a signal generator and dial in a freq that is marginally below the hearing threshold like 18Hz or so whenever their stereo is on.. It might give them some psychosomatic irritation that they cant place, then they go over and turn off the stereo, and the subharmonic resonance goes away. Crazy. Weird.

Imagecraft compiler user

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How about 22.275 Hz?

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No! Don't use that frequency! That's the Resonant Frequency of the Large Intestine!

Imagecraft compiler user

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lol the second option is only for joking :D ,beside, I don't think it's save to build one of those at home

And, why it won't work? I thought the noise cancelling technology using this kind of technique isn't it?

js wrote:
Quote:
I go for the first solution
It will NOT work, the second solution might or even getting your friendly police force involved.

Zhuhua Wu - Electronic Engineering Student

Last Edited: Thu. Aug 23, 2012 - 04:06 AM
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Are you serious? what if that frequency was used?

bobgardner wrote:
No! Don't use that frequency! That's the Resonant Frequency of the Large Intestine!

Zhuhua Wu - Electronic Engineering Student

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I don't understand how it works, are you saying people just don't like the sound of 18Hz, or

You are saying the 18Hz sound could create a subharmonic resonance?

bobgardner wrote:
Something subtle might work. Ever see those seat shakers they use in theaters and simulators? Put those on the ceiling and get a Big Fine Amp and a signal generator and dial in a freq that is marginally below the hearing threshold like 18Hz or so whenever their stereo is on.. It might give them some psychosomatic irritation that they cant place, then they go over and turn off the stereo, and the subharmonic resonance goes away. Crazy. Weird.

Zhuhua Wu - Electronic Engineering Student

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These dudes have disrespected you and kept you awake. You want to use Technology and Your Brain to outsmart them and perhaps also make them as irritated as you are. Its called Revenge. Just make sure they don't discover the odd low frequency tone that eminates from the floor of their apartment every time they turn on their stereo is coming from your apartment. Especially if they are Big and Mean and know Kung Fu.

Imagecraft compiler user

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Quote:

thought the noise cancelling technology using this kind of technique isn't it?

Wikipedia knows all: http://en.wikipedia.org/wiki/Act...

As it says there 1D (ie cancelling headphones) are much easier than 3D because of the closed/limited environment where the sound balance must be made.

If it was me I'd just put on Black Sabbath at 3am and turn it up to 11.

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While it's not as fun, a call to the landlord should take care of the problem.

/Jesper
http://www.yampp.com
The quick black AVR jumped over the lazy PIC.
What boots up, must come down.

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Call the police with a noise complaint. Do it enough times and they will get the picture.

Although my twisted mind likes the resonant frequency of the large intestine idea. The only downside to it is that at that frequency you cannot aim it very well so you will suffer the ill effects as well. :(

Hey Uncle Bob.....How the hell did you know the resonant frequency of the large intestine anyway? :?

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

"The critical shortage here is not stuff, but time." - Johan Ekdahl

 

"Step N is required before you can do step N+1!" - ka7ehk

 

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

 

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user

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Old Wives Tale. Heard a story that if you sat on the shaker table and they fed it the magic frequency, the sphincter muscle relaxes and the schtuff comes out involuntarily. Don't know if its true.

Imagecraft compiler user

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Didn't they test that myth on Mythbusters long ago?

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Reminds me of Tesla and Samuel Clemens. Here is a snippet:

Tesla in his lab in New York Tesla also applied his resonance engines in bizarre forms of physical therapy. He created machines that flooded the human body with electrical currents and strong vibrations, intended to soothe aches and promote healing. And Tesla wasn't just the inventor of the "electrotherapeutic" device -- he was also a client. He reportedly became somewhat addicted to administering the treatment to himself, insisting that a session with the machine rejuvenated him on his long stretches of work without food or sleep. Tesla once let his friend Samuel Clemens try out the healing machine. The author is said to have enjoyed the experience tremendously, until the vibrations brought him a case of spontaneous diarrhea. Tesla marketed this invention, and the Tesla Electrotherapeutic Company was one of the few commercial enterprises of his old age that was marginally successful.

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As far as loud music, a friend told me about his experience whilst at Cal Poly San Luis Obispo. He had a neighbor who played his music so loud that the neighbor had to put the record player in a closet and sound proof it so the feedback would not blow the speakers up. My friend could not even get his neighbors attention by pounding on his door one evening, so he went around back where the electric meters were. He snipped the seal with his wire cutters and then, with the music playing REAL loud, he removed and reinserted the electric meter multiple times. My friend then walked around to the neighbors door, knocked and then handed him the electric meter. He said the neighbors eyes were quite large. My friend then went back to his studies. He did not mention what the end result was but he was still smiling about it many years after.

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bug13avr,

Get a big-subwoofer, measure its outer diameter, cut a circular hole in your ceiling a little bigger than that, screw the driver to the underside of the upstairs floor boards, connect the sub-woofer to one of those $20, 200 watt amps krazatchu recommended above, and an audio-freq sweep function generator to the input of the amplifier.

Whenever they start playing their music loudly after a reasonable hour, just "sweep their floor" with some nice raspy 18-60 Hz square waves.

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Noise canceling in headphones works because the microphone is physically very close to your ear. Active noise cancellation works by inverting the "noise" signal (i.e. the hum of the airplane) and playing it through the earcups. The two signals cancel each other out, and you hear silence. Except for higher frequencies. With those, the distance between the microphone and your inner ear becomes significant enough that the phases are no longer exactly 180 degrees apart, and the noise isolation fails.

Now take your situation. You evidently want to make some sort of "noise cancellation box" that can sit on your desk and make the noise go away. The problem is, it doesn't know how far away you are from its microphone. Without that information, it cannot tell how far to shift the phase. Add to that the distinct possibility that you don't live in an anechoic chamber and therefore have to worry about echos of the sound, and it basically becomes impossible. Sorry, but maybe a better solution would be to talk to the people and ask them to turn their music down...

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jayjay1974 wrote:
Didn't they test that myth on Mythbusters long ago?

YES they did! And they busted it! ;)

It's a myth!

- Brian

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Hi Zootboy,

Thanks for taking the time to explain to me, now I may want to try the subsonic frequency method lol :)

zootboy wrote:
Noise canceling in headphones works because the microphone is physically very close to your ear. Active noise cancellation works by inverting the "noise" signal (i.e. the hum of the airplane) and playing it through the earcups. The two signals cancel each other out, and you hear silence. Except for higher frequencies. With those, the distance between the microphone and your inner ear becomes significant enough that the phases are no longer exactly 180 degrees apart, and the noise isolation fails.

Now take your situation. You evidently want to make some sort of "noise cancellation box" that can sit on your desk and make the noise go away. The problem is, it doesn't know how far away you are from its microphone. Without that information, it cannot tell how far to shift the phase. Add to that the distinct possibility that you don't live in an anechoic chamber and therefore have to worry about echos of the sound, and it basically becomes impossible. Sorry, but maybe a better solution would be to talk to the people and ask them to turn their music down...

Zhuhua Wu - Electronic Engineering Student

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No problem, I'm glad it made sense. With good noise canceling headphones (e.g. Bose), the active noise cancellation cuts out the low frequencies and the passive noise cancellation (i.e. the giant foam ear cups) cut out the high frequencies. The two actually work quite well together.

Unfortunately, as anyone who has lived under/over loud partiers can tell you, the low frequencies (the ones that sound-blocking foam has a hard time stopping) conduct through the frame of the building very well. That's why you tend to hear the bass of loud music much more than the treble. The walls block the higher frequencies, but the lows carry right through them. So aside from buying and wearing a pair of active canceling headphones, getting your inconsiderate neighbors to turn down the music is pretty much your only option.

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You could build a room in a room ;)

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This is the traditional radio/TV/recording studio approach - a box in a room. Look up 'camden walls' for details.

However, a nicely padded box 1.8m by 60cm by 30cm is much cheaper and just as effective...

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I'm not sure why the noise canceling approach wouldn't work. In my view it's all a matter of chosing the right phase angle.

While i do hold all patents on my LSPTSNCA (large-scale phase shift noise canceling algorithm), i would grant you the (noncommercial) use of it without any royalties. Here goes:

Estimate the time it takes your neighbour to go to bed from switching off his music. Add 20 minutes (that is the phase angle), then apply Led Zeppelin's Whole lotta love for half an hour with all the power your speakers can afford (that's the large scale). Make sure he doesn't miss a single tone of Jimmy Page's guitar riffs.

Adjust the phase angle and the duration based on your neighbour's look the next morning to optimize the algorithm.

In effect you are still fighting noise with noise, and if it works out as anticipated, then you indeed canceled noise with noise! Voila!

Einstein was right: "Two things are unlimited: the universe and the human stupidity. But i'm not quite sure about the former..."

Last Edited: Fri. Aug 24, 2012 - 02:15 PM
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Quote:
a nicely padded box 1.8m by 60cm by 30cm is much cheaper and just as effective...
Yes, but how will he trick the neighbour to go into it? (...Maxwell Smart voice required :? )

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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What makes you think the neighbour will be in any condition to object?

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I like the EMP suggestion. I think the cool factor over the other ideas mandates it the one to pursue.

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Geronimo wrote:
jayjay1974 wrote:
Didn't they test that myth on Mythbusters long ago?

YES they did! And they busted it! ;)

It's a myth!

I've said it before, but it deserves be repeated:

It's a myth that Mythbusters are busting any myths.

Many of the things that they say can't be done, people do anyway.

/Jesper
http://www.yampp.com
The quick black AVR jumped over the lazy PIC.
What boots up, must come down.