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krabbacitor
Joined: Aug 13, 2009 Posts: 12 Location: Hamburg
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Posted: Wed Nov 17, 2010 3:57 pm Post subject:
Some advice for lighting a random sequence of LEDs Subject description: Voltage to coordinates...kind of |
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Hi there!
OK, this is not really music related, but somehow this idea got stuck in my head and I don't really know how to do this...
I'd like to build a grid of LEDs, 5 by 5, which get randomly lit, one at a time, with a frequency of about 1 or 2 Hz, slowly fading, then another randomly chosen one.
I would like to do this without a microcontroller, so I thought of basing this on a noise source (zener or reverse biased transistor), some kind of sample (and hold) and a 555-clock. The timer triggers the sample and hold for a random voltage from the noise source.
Now I'm looking for an easy way to connect this random voltage with the grid of LEDs. So the basic question is (besides the question why I don't want to use a microcontroller): What would be some clever way to turn a random voltage level into a coordinate?
I thought about using 4066-switches or multiplexers, two timers and two noise sources, logics, etc...
Another idea is to actually use a timer to both cycle through the LEDs and sample the voltage continually at a higher frequency, lighting the actual LED if the sampled voltage crosses a specific threshold - so this would be based on chance but that's not what I want.
I'd be glad to hear some ideas from you!
Regards
Christian |
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ian-s
Joined: Apr 01, 2004 Posts: 2669 Location: Auckland, New Zealand
Audio files: 42
G2 patch files: 626
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Posted: Wed Nov 17, 2010 5:39 pm Post subject:
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maybe use a couple of bargraph drivers for row / column.
Not sure how you would get the columns working though. |
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krabbacitor
Joined: Aug 13, 2009 Posts: 12 Location: Hamburg
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DrJustice
Joined: Sep 13, 2004 Posts: 2114 Location: Morokulien
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Posted: Fri Nov 26, 2010 11:54 pm Post subject:
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krabbacitor wrote: | ...i still don't want to use a microcontroller... |
Why don't you want to use a microcontroller?
The solution you outlined requires a _lot_ of components - yes, it seems overly complicated to me.
A small and cheap uC (e.g. an 8 pin PIC or AVR) is the most natural and elegant solution for this job, driving a few daisy chained shift registers to power the LEDs. Alternatively, a similar uC in a larger package (typically 40 pin) would give you a cheap single chip solution.
DJ
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Tim Servo
Joined: Jul 16, 2006 Posts: 924 Location: Silicon Valley
Audio files: 11
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Posted: Sat Nov 27, 2010 1:13 am Post subject:
Some advice for lighting a random sequence of LEDs |
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I think using two LM3914 bar graph drivers (as suggested earlier) would be the way to go. I'd use the noise source and two sample/holds, one for the row, and one for the column. I'd alternate samples between the row and column drivers, and there you go. Might also be fun to feed two different LFOs into the row and column drivers.
Tim (Random is my middle name) Servo |
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sneakthief
Joined: Jul 24, 2006 Posts: 569 Location: Berlin
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