=== graphic analyzer & vu-meters === - diyAudio
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Old 5th October 2004, 11:48 AM   #1
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Default === graphic analyzer & vu-meters ===

Hi to all!

I want to build an audio graphic analyzer on 10, 20, 30 bands with individual bandpass filters and vu meters.
I have searched with google but the results were very poor.

If anybody have the schematic, links for this please post it here

- What is the best choice for a cheap vu-meter ? I want to make more then 20 vu meters and if I choose LM3915 I have to pay a lot ...

Also I want schematics or links ..

Please help
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Old 8th October 2004, 11:31 AM   #2
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I want something like that ... bu with 10 leds per band:
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Old 13th October 2004, 03:11 AM   #3
dangus is offline dangus  Canada
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There was a project in the american magazine Popular Electronics around 1977 for a 10 band RTA. It used a single LM3915 to drive a multiplexed display, and op-amp bandpass filters for each band. I'm slowly building one. Email me and I might be able to scan the article.

I think Rohm has some chips for equalizers and displays, alrhough from what I remember they were more like 5 bands for ghetto blasters and low-fi systems. They might also have some bar graph drivers that are cheaper than the old National Semi parts.

Alternatively, use an old PC with a sound card and run some RTA software. Scrounge a video card with TV-out and you can watch it on your TV. A pentium should be fast enough.

Or, cruise the pawnshops and there's a good chance you'll find an old graphic equalizer with a built-in RTA, for not much money.
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Old 19th April 2005, 10:22 PM   #4
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I was wonder if anyone knows how to make a 10x10 matrix (LEDs) VU spectrum analyzer with the help of the printer parallel port.

It can be useful for those who desire a fancy audio "visual"

I saw a schematic for 16x16 matrix but the i don't know how to start it because it does not mention anything about software.

Adrian,
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Old 19th April 2005, 10:40 PM   #5
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Adrian,

In May of 2004, Dr. Dobbs magazine published an article explaining how to convert a Nintendo Gameboy into a spectrum analyzer. The cost at the time was around US $70.
Maybe that is an affordable alternative to what you want to do.
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Old 20th April 2005, 12:35 AM   #6
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Heya Grim, do you have this magazine, and are you willing to sell it?

Trev
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"Every technique can be used in a great many ways, but mastering it, thats what realy counts."
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Old 20th April 2005, 01:04 AM   #7
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The article is available on-line and I think you can get a six months limited access membership at no cost. You can find it here:

http://www.ddj.com/documents/s=9132/ddj0405p/0405p.htm
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Old 20th April 2005, 01:55 AM   #8
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Default Re: === graphic analyzer & vu-meters ===

Quote:
Originally posted by adrianbodor
Hi to all!

I want to build an audio graphic analyzer on 10, 20, 30 bands with individual bandpass filters and vu meters.
I have searched with google but the results were very poor.

If anybody have the schematic, links for this please post it here

- What is the best choice for a cheap vu-meter ? I want to make more then 20 vu meters and if I choose LM3915 I have to pay a lot ...

Also I want schematics or links ..

Please help
Here's a much easier way to do it (than driving yourself crazy building dozens of bp filters) -- get yourself a Zetex ZFX36L01 chip -- it can do bandpass and notch with adjustable Q -- and it can be swept !!!

use a clock to periodically sample and hold the signal -- you can generate the sweep with a couple CMOS logic chip -- or if you want to use the serial port on your computer you can write the appropriate code.

there are some advantages to using analog vs FFT
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Old 31st March 2007, 07:10 PM   #9
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Default ZFX36L01

no longer available
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Old 31st March 2007, 07:57 PM   #10
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Default Re: ZFX36L01

Quote:
Originally posted by ppcblaster
no longer available
Yupp, they don't even list it in their catalog of obsolete products -- you could replicate the device with an analog devices mixer and VCO -- I would use a crystal filter rather than an analog filter, however.

btw, Zetex did send me an evaluation board and a couple of chips but this must have been 5 years ago.
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