[sdiy] Bar Graph Driver as Quantanizer

[Kyle Stephens]

Stage effects, yes! I've had grand dreams of building a modular/stackable frequency visualizer, not unlike the cover to Apoptygma Berzerk's "Harmonizer" (http://www.poponaut.de/images/_apb_4046661085822.jpg). Personally I'd want square "bars," in solid blue or green :).

Each unit would be about a yard to a side, with 10x10 bars beneath some frosted white plexiglass or similar. Keeping enough opacity to not see the insides while being just transparent enough to let light through is something I'm still pondering... maybe just strategic masking on the backside of lightly frosted plexi. The stackable idea would come into play as multiple units could be ganged together electronically and physically to a width and height tailored to the stage. Each otherwise independent unit would detect its space within the stack, dynamically adjusting for scale of the frequency bars. For maximum coverage, keeping the stack rectangular would work best, though I guess if there's a lot of mids or just lots of lows and highs, a pyramid or inverted one could work without squishing anything...

To keep it simple I could run it with an array of just 3915s, or getting more complicated I could sequence graphics through the screen with a microcontroller, which would have a resolution of, let's see... If I made the squares 3 inches to a side, putting aside the spacing between them for the time being (which would be ~1/2", 36"-30" = 6" over 11 spaces from the sides and between the squares, thus 6/11")...

Resolution = (10 x length units) x (10 height units) @ 1/3 DPI (that's 4 DPF, dots per foot, again ignoring the spacing between the boxes).

Ooh, I could rig up a webcam or an old CCD, and feed it to the screen for some some ultra high contrast (1 bit!) crowd/band shots :)

When I get through with the 3914 quantinizer, I might make some small scale  prototypes. If 1 bar-box equaled 1 LED, and using 10 1/4" LEDs for say with some spacing wiggle room , call it 3" to a side of a unit, with 1/22" spacing between LEDs. Sounds like SMT time...


_Kyle

--- On Tue, 2/3/09, Roy J. Tellason <rtellason at verizon.net> wrote:

> From: Roy J. Tellason <rtellason at verizon.net>
> Subject: Re: [sdiy] Bar Graph Driver as Quantanizer
> To: lightburnx at yahoo.com
> Date: Tuesday, February 3, 2009, 2:40 PM
> On Tuesday 03 February 2009 04:28:17 pm Kyle Stephens wrote:
> > All Electronics:
> >
> >
> http://www.allelectronics.com/make-a-store/item/LM3914/BARGRAPH-DISPLAY-DRI
> >VER/-/1.html
> >
> > They have discontinued LM3900 current op-amps too
> (picked up a few of those
> > as well):
> 
> What are those good for?  I've seen the very occasional
> use of them over the 
> years since I've first heard of them,  but have really
> little idea what I'd 
> do with one.
> 
> >
> http://www.allelectronics.com/make-a-store/item/MC3401/QUAD-OP-AMP-EQUIV.-3
> >900/-/1.html
> >
> >
> > Good note on the current, not voltage, for the
> outputs, thanks!
> >
> >
> > _Kyle
> 
> Going back a bunch of years,  I had built a little
> "module" of sorts that had 
> one of those (a 3915 actually) and an op amp filter in
> front of it,  I think 
> I used a 3140 on that.  The output of this went to a molex
> connector.  Then I 
> built a hunk of perfboard with LEDs and a matching
> connector plus 2-pin power 
> plug.  Later on I built another board with ten
> two-transistor stages and 
> couple that to a strip I had with a bunch of bayonet
> sockets on it and used 
> ten #47 bulbs instead of LEDs.  I recall putting 100 ohm
> (?) resistors across 
> the transistors that were driving the bulbs to keep them
> just barely warm,  
> and it gave them a barely perceptible glow on the ones that
> weren't lit.
> 
> Further thoughts on that were to build another interface
> board and have that 
> driving MOC3010 optos which would drive triacs,  but that
> would've involved a 
> big jump in what I was spending on hardware and the budget
> for it just wasn't 
> there at the time.  I thought if I could figure out how to
> package it right,  
> and if you fed the right signal into it (say mic a kick
> drum or something),  
> it'd be nice for a stage effect to have for a band, 
> maybe.   :-)
> 
> 
> 
> 
> -- 
> Member of the toughest, meanest, deadliest, most
> unrelenting -- and
> ablest -- form of life in this section of space,  a critter
> that can
> be killed but can't be tamed.  --Robert A. Heinlein,
> "The Puppet Masters"
> -
> Information is more dangerous than cannon to a society
> ruled by lies. --James 
> M Dakin