So I need to make an LED grid.
The input will be an constantly changing analog signal (whose voltage ranges I don't know yet). I need to rectify the signal (convert all the negative voltages to positive), then I'd like to light up a different number of LEDs based on the value of the rectified signal. If it's low voltage (but higher than zero), then I'll want 4 (or maybe 6 or 8) of some color LED to light up (say blue). At a slightly higher voltage, I'll want the 4 blue LED's to light up, but also 4 more LEDs (say green) to light as well. At a slightly higher voltage, I'll have the 4 blues, 4 greens, and 4 yellows (or whatever color) light up. I'd like to have at least 4 different stages (each stage being 4 more LEDs light up), and this needs to be voltage regulated (I don't want to blow the blues, when I have a high enough voltage to turn on the yellows).
The input voltages will be changing pretty fast, so ideally this needs to be pretty responsive.
Because this is a school project, I need to be able to build as much of this as possible with just basic components (R's, L's, C's, transistors, op-amps, diodes, etc) as opposed to just buying ICs which do everything for me.
I figure I can rectify it with something like this
at the front, I should be able to use switches with varying resistors to turn on each new set of LEDs, but how do I regulate the voltage so that I don't blow the first stage (blue) LED's when I turn on later stage (yellow) LED's?
What negative voltages? Where is the analog signal coming from? What does this have to do with an Arduino? Can you post a picture or drawing of this grid?
What your describing sound like a voltage or signal meter which can easily be done on an arduino. This can also be done with some simple comparator chips, like a LM339 or LM324, both of which can be bought at RadioShack or online.
Run your rectified voltage thru 3 comparators, rectifed signal into + input, compare level into - input. Output goes when + signal is > than - signal.
Use the output to drive a transistor that sinks current from LED cathodes. Anode to +V with appropriate current limit resistor.
When you put it all together what you probably wind up with is a 60's genre "Color Organ" or what the English call "Sound to light generator/converter".
Also, you'll need a recorded copy of Jimi Hendrix "Voodoo Child" to use as the test signal..
raschemmel:
When you put it all together what you probably wind up with is a 60's genre "Color Organ" or what the English call "Sound to light generator/converter".
Nah, they have bandpass filters to select by sound frequency.
I knew I forgot something.. (probably because I grew up in the 60's...)
Footnote- I built a color organ with a 10 band octave equalizer using Walter Jung's Op Amp Active Filter Cookbook and a bunch of
LM307 op amps and it came out studio quality. (it had RadioShack pots)
raschemmel:
I knew I forgot something.. (probably because I grew up in the 60's...)
Footnote- I built a color organ with a 10 band octave equalizer using Walter Jung's Op Amp Active Filter Cookbook and a bunch of
LM307 op amps and it came out studio quality. (it had RadioShack pots)