Switching on several LED's with a single button push / gradual dimming of a LED?

[M.U.L.E.]

Greetings

I've built and finsihed a midibox sid v2 that I'm excited to share pics of. It's lacking one feature that I'm hoping to get some help with (and that's keeping me from moving on). What I would like to do is be able to push a single button to turn on several LED's arranged inside. These LED's are only being used for light, and not for any specific function. I'm not sure how many led's I will be using - I'd like to use as many as possible without taxing the power supply or regulators (if this is indeed what I should be concerned with). I've assembled a stereo sid setup using the optimized psu v2 schematic, and have built the simple control surface setup (with a few extra additions, two more buttons and leds).

I guess this would be two separate issues, first I'll ask about this minus the dimming aspect. How many led's could I use for this idea, and what would I need to do to be able to turn them all on with the push of a single button (a button dedicated to turning those on, and I guess off when pushed again)? I would like them to be as bright as possible, also wondering which led's to use (I have about 50 standard brightness red T1 3/4 ones I bought, not so bright though) I have one DIN mounted inside my enclosure. I'm only using two of the shift registers on the DIN that's in there, I'm thinking I might be able to use the other two and the rest of the unused pins to connect led's to? I have room for maybe one more DIN inside my enclosure. Also would I just need to add some things to the setup_6581.asm, similar to how the SID L/R addition works ( http://www.midibox.org/dokuwiki/doku.php?id=adding_two_buttons_for_l_r_sid_selection_instead_of_one&s[]=led&s[]=din )?? Not quite sure how to approach this.

And secondly, do any of you have some ideas concerning the one or two second delay dimming upwards? The effect I'm going for is a one to two second delay, gradually going from off to full brightness. Basically from dim to bright in two seconds. Or something close. I did find some info here and there on the net about dimming led's using PWM, and saw that someone started a topic here about it as well, but it didn't appear that there was any answer. I would also consider using a potentiometer to control the brightness. I am open to any ideas, I'd love to put something together and try it out.

And lastly I appreciate any efforts to help me realize this, even if it's just to be able to turn a mess of LED's on and off with one button, since that is the heart of what I want to do. :) The dimming would be a really great addition, and once you see what it is I've built it into you'll understand. I had a great time building this and not too much trouble doing it thankfully, however I couldn't have had such an easy time without so much great documentation and helpful posts on this forum by all you guys. Now how to get a bunch of led's to turn on . .

[stryd_one]

I would say that, seeing as the lighting has nothing to do with the midibox (electronically speaking) I wouldn't involve the midibox in it at all... I'd just search the net for schematics, ask on LED forums, etc etc..

[Goblinz]

I would say that, seeing as the lighting has nothing to do with the midibox (electronically speaking) I wouldn't involve the midibox in it at all... I'd just search the net for schematics, ask on LED forums, etc etc..

They have whole forums for LED's?  OMG! I've always wanted people to discuss the contents of my knightbright catalogue with.

***G runs off to find one***

Do they have knob forums too?

[H2O]

(I'm assuming you mean DOUT not DIN... and the idea is you want midibox's DOUT to drive your lights.  If I'm on the wrong track, just ignore me ;))

Been looking into something similar to this myself, lately.  Nothing even tested yet, just a few ideas.

More/brighter LEDs = more current.  Traditionally, LEDs plug straight into the DOUT shift register (with a current limiting resisitor of course).  From what I gather, there's a limit to how much current you can pull through the 74HC595.  If you need/want more than that, I hear there's a higher-current version of the chip around.  Alternatively, I've been thinking about somehow driving a transistor to isolate the 74HC595 from the LED (haven't had time to try it yet, though).

I would say that, seeing as the lighting has nothing to do with the midibox (electronically speaking) I wouldn't involve the midibox in it at all... I'd just search the net for schematics, ask on LED forums, etc etc..

I imagine a simple, non-midibox capacitor circuit could do your fades without having to resort to a messy midibox-driven PWM.  Something similar to these perhaps.

Hope this helps!

[stryd_one]

***G runs off to find one***

Do they have knob forums too?

Hahaha! alas I've never seen one, but I have seen forums full of dudes discussing LEDs. Damn geeks!