Timed LEDs? - Tilted Forum Project Discussion Community

MooseMan3000 · 12-11-2005, 05:45 PM

Basically, what I want to do is this: to be able to have 50 or so LEDs light up at different times. They're going to (most likely, but I'm not decided entirely yet) be powered off a single 12 V DC connection, so I'd want to have a set number of them on at a single time (whatever gets me closest to that 12 V)

The only way I can think of to do this at the moment is to wire several circuits in parallel, each with X LEDs (whatever that number above is) in series. On each of those circuits, I would also throw varying capacitors/timers. The capacitors would sort of go off randomly. If I used an IC 555 timer, each set of LEDs would go off at a set interval. Is there something I'm missing, or something I should know?

Also, can someone think of a better way to do it than the method I've described above? (i.e. is there a way to make it totally random without running the risk of overshooting the voltage on a single LED and blowing it? Should I make individual circuits for all 50 with resistors to make up the rest of the voltage?)

Extra credit: Find a way to time it to music, rather than having it simply be random. I have two possibilities for this. One is using a microphone connected to the circuit somehow, most likely in combination with capacitors. The other is to somehow directly connect to my sound source (in this case a sound card), likely at line level, and with any luck, I can connect directly to the sub output. Extra extra credit: Find a way to do this without physically altering the sound card, so that it can be swapped out in the future without soldering/desoldering anything.

I've only just begun thinking of this specific part of the project, and I'm struggling to come up with a decent solution. Any help would be greatly appreciated.

goddfather40 · 12-11-2005, 09:31 PM

Remember that if you set up the LEDs in series, each LED will drop about 0.6 volts along with the resistor drop. I'm not quite sure off the top of my head what a 555 can drive current wise as well, you will have to watch how much current you're trying to source as well. I would use a single 555 timer driving some BJT's and put the capacitors in the base leg of the transistors, may have like 10 BJT's each driving 5 LED's. I know you want the blinking to be random, but you can also use flip flops to divide the 555 frequency how ever you like.

Martian · 12-11-2005, 10:36 PM

The music part is easy. Grab yourself a set of stereo headphones. Now, here you can go two options. You cut off the earpieces, then you can either twist the signal wires together or keep them seperate and connect them to seperate clusters or LED's to have one set react to each channel (left/right). I'm not an electrical engineer, so I'm not sure if you'll need to amplify the signal or not as I have no idea how much current an LED will take. In any case, if you use that as the input on your LED's the signal will be amplitude modulated according to the signal(s) coming out of the line jack on your sound card (where the stereo jack plug you took off the headphones is connected) which, if I remember my electrical theory correctly, ought to give you the desired effect. If you want to get really fancy, you can build the LED's and amp (if necessary) into an enclosure and have yourself a little musical lightbox. It's portable and it will plug into any 1/4" headphone jack, which will make it suitable for use with a lot more than just a PC. Also, it'll be fucking cool.

flat5 · 12-12-2005, 04:57 AM

Off the top of my un engineer head:

Use an AC to 5 VDC adapter and TTL logic.

Perhaps 7 segment LED drivers (7) and adjust the strobe rate for the effect you want.

You could AND this with an audio signal driven comparator output. Again adjust for effect.

MooseMan3000 · 12-12-2005, 08:43 AM

Quote:

Originally Posted by Martian

If you want to get really fancy, you can build the LED's and amp (if necessary) into an enclosure and have yourself a little musical lightbox. It's portable and it will plug into any 1/4" headphone jack, which will make it suitable for use with a lot more than just a PC. Also, it'll be fucking cool.

Perhaps I wasn't specific enough. It's in the computer. It's so simple! [/Zoolander] If it was simply a matter of plugging into a headphone jack, I would do exactly what you described. Right now I'm considering soldering in a second connection in parallel to the existing headphone jack, though I'd prefer not to physically alter the card, so I'm debating.

Quote:

Originally Posted by flat5

Use an AC to 5 VDC adapter and TTL logic.

Perhaps 7 segment LED drivers (7) and adjust the strobe rate for the effect you want

I wouldn't need an AC to 5 VDC, since I would be using a computer power supply which has a 5 V rail. However, using a seven segment driver seems unnecessarily complicated for this project... though it's an idea. I'll think on that. Thanks!

flat5 · 12-12-2005, 12:20 PM

I was thinking it might help the random effect - provide the drive current - and it's been many years, but, don't some segment drivers have an enable pin? This would allow the blinking along with sound (music) level.

It might be a mess to breadboard, but the pcb would look clean :-)

You don't need to alter the soundcard so much. Just tack solder a light cable to two pads on the card. You can find a large ground area for the shield and a perhaps the line output pad for signal. I would run this to a cmos comparator.

I have not fooled around with this stuff since the 70s - early 80s.
Designed an octive divider for saxophone (that worked).

Martian · 12-12-2005, 12:31 PM

Quote:

Originally Posted by MooseMan3000

Perhaps I wasn't specific enough. It's in the computer. It's so simple! [/Zoolander] If it was simply a matter of plugging into a headphone jack, I would do exactly what you described. Right now I'm considering soldering in a second connection in parallel to the existing headphone jack, though I'd prefer not to physically alter the card, so I'm debating.

Well, why didn't you say so?

I'm still not clear.. couldn't you just do above and run the connector out through an open card slot in the back of the case?

MooseMan3000 · 12-12-2005, 01:30 PM

Quote:

Originally Posted by Martian

I'm still not clear.. couldn't you just do above and run the connector out through an open card slot in the back of the case?

Well, I could... but that would be ugly

. That's the only reason, but for me it's reason enough to avoid that solution. I mean, it's a custom case, here. I don't want it to look too amateur.

Quote:

Originally Posted by flat5

don't some segment drivers have an enable pin?

Not that I'm aware of, but that doesn't mean they don't exist. I'll look into that.

Quote:

Originally Posted by flat5

I would run this to a cmos comparator.

Eh? I haven't used a comparator before, so I'm not entirely sure what they do. If I understand it correctly, they work as an interface for an external sensor... would I use that to control the pulsing of the LEDs when connected to the audio source?

flat5 · 12-12-2005, 04:34 PM

Yes. Above a compared voltage, the output logic level switches.
Use that to control if an LED will light or not.
All segments off unless the comparator says "let there be light".
It's likely that you will have to play with de-glich stuff or time constants though.
Probably follow the trigger with a timer (555).
Switching at an audio rate is too fast.
http://hyperphysics.phy-astr.gsu.edu...opampvar8.html

Here is info on 7 segment drivers. You can enable or un-enable all segments.
http://www.play-hookey.com/digital/e...eg_driver.html

It might help you decide on an approch or the parent page may give you other ideas.
I'd like to know how you follow up on the project!

Oh yeah, you could use small clip leads to the soundcard or a double jack.
A tee jack (one input two output) connected to the line output on the soundcard.

12-11-2005, 05:45 PM	#1 (permalink)
MooseMan3000 wouldn't mind being a ninja. Location: Maine, the Other White State.	Timed LEDs? Basically, what I want to do is this: to be able to have 50 or so LEDs light up at different times. They're going to (most likely, but I'm not decided entirely yet) be powered off a single 12 V DC connection, so I'd want to have a set number of them on at a single time (whatever gets me closest to that 12 V) The only way I can think of to do this at the moment is to wire several circuits in parallel, each with X LEDs (whatever that number above is) in series. On each of those circuits, I would also throw varying capacitors/timers. The capacitors would sort of go off randomly. If I used an IC 555 timer, each set of LEDs would go off at a set interval. Is there something I'm missing, or something I should know? Also, can someone think of a better way to do it than the method I've described above? (i.e. is there a way to make it totally random without running the risk of overshooting the voltage on a single LED and blowing it? Should I make individual circuits for all 50 with resistors to make up the rest of the voltage?) Extra credit: Find a way to time it to music, rather than having it simply be random. I have two possibilities for this. One is using a microphone connected to the circuit somehow, most likely in combination with capacitors. The other is to somehow directly connect to my sound source (in this case a sound card), likely at line level, and with any luck, I can connect directly to the sub output. Extra extra credit: Find a way to do this without physically altering the sound card, so that it can be swapped out in the future without soldering/desoldering anything. I've only just begun thinking of this specific part of the project, and I'm struggling to come up with a decent solution. Any help would be greatly appreciated.

12-11-2005, 09:31 PM	#2 (permalink)
goddfather40 Llama Location: Cali-for-nye-a	Remember that if you set up the LEDs in series, each LED will drop about 0.6 volts along with the resistor drop. I'm not quite sure off the top of my head what a 555 can drive current wise as well, you will have to watch how much current you're trying to source as well. I would use a single 555 timer driving some BJT's and put the capacitors in the base leg of the transistors, may have like 10 BJT's each driving 5 LED's. I know you want the blinking to be random, but you can also use flip flops to divide the 555 frequency how ever you like. __________________ My name is goddfather40 and I approved this message. I got ho's and I got bitches, In C++ I branch with switches -MC Plus+

12-11-2005, 10:36 PM	#3 (permalink)
Martian Young Crumudgeon Location: Canada	The music part is easy. Grab yourself a set of stereo headphones. Now, here you can go two options. You cut off the earpieces, then you can either twist the signal wires together or keep them seperate and connect them to seperate clusters or LED's to have one set react to each channel (left/right). I'm not an electrical engineer, so I'm not sure if you'll need to amplify the signal or not as I have no idea how much current an LED will take. In any case, if you use that as the input on your LED's the signal will be amplitude modulated according to the signal(s) coming out of the line jack on your sound card (where the stereo jack plug you took off the headphones is connected) which, if I remember my electrical theory correctly, ought to give you the desired effect. If you want to get really fancy, you can build the LED's and amp (if necessary) into an enclosure and have yourself a little musical lightbox. It's portable and it will plug into any 1/4" headphone jack, which will make it suitable for use with a lot more than just a PC. Also, it'll be fucking cool. __________________ I wake up in the morning more tired than before I slept I get through cryin' and I'm sadder than before I wept I get through thinkin' now, and the thoughts have left my head I get through speakin' and I can't remember, not a word that I said - Ben Harper, Show Me A Little Shame

12-12-2005, 12:20 PM	#6 (permalink)
flat5 Very Insignificant Pawn Location: Amsterdam, NL	I was thinking it might help the random effect - provide the drive current - and it's been many years, but, don't some segment drivers have an enable pin? This would allow the blinking along with sound (music) level. It might be a mess to breadboard, but the pcb would look clean :-) You don't need to alter the soundcard so much. Just tack solder a light cable to two pads on the card. You can find a large ground area for the shield and a perhaps the line output pad for signal. I would run this to a cmos comparator. I have not fooled around with this stuff since the 70s - early 80s. Designed an octive divider for saxophone (that worked). Last edited by flat5; 12-12-2005 at 12:24 PM..

12-12-2005, 04:34 PM	#9 (permalink)
flat5 Very Insignificant Pawn Location: Amsterdam, NL	Yes. Above a compared voltage, the output logic level switches. Use that to control if an LED will light or not. All segments off unless the comparator says "let there be light". It's likely that you will have to play with de-glich stuff or time constants though. Probably follow the trigger with a timer (555). Switching at an audio rate is too fast. http://hyperphysics.phy-astr.gsu.edu...opampvar8.html Here is info on 7 segment drivers. You can enable or un-enable all segments. http://www.play-hookey.com/digital/e...eg_driver.html It might help you decide on an approch or the parent page may give you other ideas. I'd like to know how you follow up on the project! Oh yeah, you could use small clip leads to the soundcard or a double jack. A tee jack (one input two output) connected to the line output on the soundcard. Last edited by flat5; 12-12-2005 at 04:40 PM..

12-12-2005, 04:57 AM	#4 (permalink)
flat5 Very Insignificant Pawn Location: Amsterdam, NL	Off the top of my un engineer head: Use an AC to 5 VDC adapter and TTL logic. Perhaps 7 segment LED drivers (7) and adjust the strobe rate for the effect you want. You could AND this with an audio signal driven comparator output. Again adjust for effect.