propeller based audio vu meter?

OakGraphics

saw some pictures from the last gathering that somebody made a huge vu meter with christmas lights. was that project ever shared?

looked cool

VIRAND

That's what the good old LM3916N chip is used for, since 1980 or so.

I made one back then with real bulbs, which used 10 relays, but now the same effect can be
done with those new LED christmas lights that are the same shape as those bulbs, just using
the typical LM3916 circuit plugged into the aux line-level-out jack of an amplifier
(boom box, stereo, hi-fi, tape deck, all that good old pre-ipod stuff).

But I've been thinking about using those Propeller FFT programs some of us have been working on to
make those psychedelic trippy videos out of music like music software does. They do that with FFT.
The simplest FFT music visualizer is the graphic equalizer spectrum analyzer effect, and someone
has a working Propeller FFT with 1024 frequency spectrum bands, although it needs a separate
ADC chip, and some of us have been trying to make it work without one.

Maybe google TQUALIZER. I think that's what you want.

Post Edited (VIRAND) : 10/19/2009 7:38:32 AM GMT

OakGraphics

I did find an application note from maxim that was interesting. http://pdfserv.maxim-ic.com/en/an/AN4620.pdf
Basically they used 1 12bit adc and some logic 74HC series to drive a pair of 74HC595 to make a 12 step lightbar. (in their example using just 6 of the 12). Kinda cool considering no actual CPU per say in the circuit.

I also saw the TQUALIZER - the display looks way cool. If I could drive that at line level then the desktop version of that would be fun to install for show - but not quite what I was looking for.

One of my projects would also be a graphic VU display that showed peak history, warned of clip and too-low signal. I want to make this for a control booth for recording live performances. The main mixer on the 1st floor has all the cool trims, but they are worried more about live sound, and not recording levels. When it gets to the tech booth upstair, we need somebody to ride the levels for the difference between presenter and music. The display they have for the meters is crazy small, and old lcd green screen that's very hard to read. So I thought of jazzing it up a bit with something 'bigger' So I was thinking of making a LCD based version - something like this for starters....

OakGraphics

After looking at the TQUALIZER display to see how much can be hacked, it seems it's a pre-rendered UL panel with 6 or 8 segments, and doesn't actually display the a spectrograph of the audio. So looks cool but is not accurate for anything that I would use.

Bean

If you do want to use the Propeller, here is some code I posted in the PropBASIC thread that uses the demo board microphone and LEDs to make a VU meter.

You could probably mangle it into something more useful.

Bean.



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Does that byte of memory hold "A", 65, $41 or %01000001 ?
Yes it does...

OakGraphics

Cool - thanks bean! I will check it out tonight.