calling all led gurus...

[onesexyga]

UPDATE. FINISHED. PICS ON THE LAST POST.






Okay, so its not a grand am, but it is an led project. I'm looking to install led lighting in a wall. My architecture school has a student run store that's open at night. The students who run it on work study leave the lights on in the store, and work in studio. If someone needs them, they find out who's running the store that night, and go find them in studio. Problem is the full overhead lighting in the lounge gets left on basically all night every night. Of course being architects, were on a bit energy conservation kick. The wall between the lounge and store is steel framed with a clear corrugated plastic finish. A color coded led lighting system, in addition to looking BA inside the clear wall, would mean we could shut the lights off and use a designated color to say who's on that night. I've got 15 each of 7 colors of led's ordered. I'll wire them in series and parallel to match whatever voltage I run. I'll need to have 7 switches. My question is what should I run to power them? First off, I cant hard wire anything, since its illegal. I am not a licensed electrician. I could run a power supply, but since 15 or so led's will use so little power, id rather not run a full power supply, just to generate a bunch of heat and waste energy. I could run a big battery, considering it would take a long time for 15 led's to run a battery down. Any imput?

[WeibSunder]

I would use a power inverter that has a (-) screw port and a (+) screw port and just set it to 12V or whatever voltage you plan on using and do it that way. Maybe you know what I'm talking about.

[ZOMGVTEK]

Im confused as to what you want to light up. Is it a small clear panel?

What type of led's do you plan on using, 5mm?

Your best bet would be to get a 12VDC adaptor from radioshack or something and wire the led's into that. For such a simple setup as this, you dont need any regulation other than resistors. Now, the vF of the differnt color led's is going to varry, so they will likely need different values of resistors. Your going to want to run them in 5 series of 3 each with a resistor for each 3 in series. You can very easily run this off a 1000mA small power supply that will just plug into the wall and you can run the power into the switches from there, and id say connect ground to all, and switch the +12v.

Any questions?

[cardude007617]

dont they make LEDs that run on 110/120?

[ZOMGVTEK]

dont they make LEDs that run on 110/120?

LOL, no...

And if they did, it wouldnt be safe for him to make this anyways...

[onesexyga]

I have my wiring planned. I wont be using resistors, because ill run them in series to match whatever voltage I end up running, then ill just run sets of those in parallel. I'm lighting up a steel framed wall cavity with a corrugated plastic sheathing. The led's are 5mm. I have 105 ordered, I'll use somewhere south of that to be safe. If I end up with a dud, or blow one, I'll want replacements. What I'm looking to do is use the most efficient mode of powering possible. Hence the led's and no resistors. What I'm wondering is what kind of life i could get out of say a standard rechargable battery. That way there it could be an entirely independent electrical system. If not, I'm looking for a power supply that wouldn't draw excessively. No sense in running a power supply that draws a constant high wattage, when all i need is some fraction of a watt to power at most 15 led's at a time.

[ZOMGVTEK]

I have my wiring planned. I wont be using resistors, because ill run them in series to match whatever voltage I end up running, then ill just run sets of those in parallel. I'm lighting up a steel framed wall cavity with a corrugated plastic sheathing. The led's are 5mm. I have 105 ordered, I'll use somewhere south of that to be safe. If I end up with a dud, or blow one, I'll want replacements. What I'm looking to do is use the most efficient mode of powering possible. Hence the led's and no resistors. What I'm wondering is what kind of life i could get out of say a standard rechargable battery. That way there it could be an entirely independent electrical system. If not, I'm looking for a power supply that wouldn't draw excessively. No sense in running a power supply that draws a constant high wattage, when all i need is some fraction of a watt to power at most 15 led's at a time.

Well, it looks like we have some learning to do here...

First off, you cannot run led's with no form of regulation, they wont make it past 2 seconds. You NEED resistors on them with enough overhead to be able to regulate the current well. So, dont run 5 ohm resistors to try and cut down on the power lost in the resistors, its not going to work. If you want to be as power efficent as possible, get a whole bunch of led's and run them at 5-10mA, theyre significantly more efficient at lower currents. And what is a standard rechargeable battery? Are we talking a small sealed lead acid, a AA NIMH, or what? The problem with running led's off a small battery would be that they are going to dim rather rapidly, and you would need to swap out the battery constantly to get them back up to brightness. If you really wanted to suck all the power out of the batterys, you would run a efficent step up current regulated regulator that would run say 60mA out, but you would need one for each of the channels of different color led's and that pricey. Your best bet by far is to get a small power supply and run that. A 12v 1000mA power supply will be 70-80% efficent, and it does NOT draw its full rated current constantly, where would it go? If you arent drawing anything from it, it would start smoking after 5 mins, and they dont do that...

Get a 12V power supply from radio shack or something, for 3 series led's depending on the color, i would run somewhere along 3-400 ohms on each series of 3. http://led.linear1.org/led.wiz this is a helpful wizard. It will tell you the power dissipated by the resistor. You can play around with the imput voltage to get the power dissipated down. The key would be getting the vF as close to the source voltage as possible, but then you have to worry about varying led's voltages coming into play. Unless you really knew what you were doing and bought some super expensive matched binned led's, then all of your vFs's are going to varry by .2-.6 V among different led's, even of the same color...

[onesexyga]

No, you dont need resistors. If you run them in series, the voltage will split between the leds. I know this for a fact. Ive been doing it for years. As for power supplies only drawing what they require, well thats just not true. Feel a power supply. They heat up. Thats where the additional draw goes. Leave a charger plugged in with nothing on it. It sure draws power anyways. As for the leds running different voltages, well they all vary slightly, yes, but as long as I run within the range or below, they wont blow. And as for even light output. That has less to do with the voltage and more to do with the color. Anyone else have some imput?

[ZOMGVTEK]

Oh, so your a electrical engineer too?

[ZOMGVTEK]

Id suggest you might want to browse candlepowerforums.com for a good while before you attempt this project. But from your last post, it appears you already at least think you know what you are doing, so whats the point of this thread?

[onesexyga]

No, im not an electrical engineer, but you honestly cant tell me that you cant run an led without a resistor, and that intensity is entirely dependent on voltage imput and not on the color of the led. I've actually got some help from some engineers here who know what there talking about. Im all set now. Thanks anyways.

[onesexyga]

I will post pics of the final install.

[Ajaxus]

Ignore the new kid..been talking **** and making idiotic posts since he arrived..not even sure why a Honda Accord owner signed up for these forums anyways..

[ZOMGVTEK]

No, im not an electrical engineer, but you honestly cant tell me that you cant run an led without a resistor, and that intensity is entirely dependent on voltage imput and not on the color of the led. I've actually got some help from some engineers here who know what there talking about. Im all set now. Thanks anyways.

While it is possible to run a LED without a resistor, its not exactly good practice. It would provide little regulation, and rely on the voltage of the led not shifting over time like often found in all led's. If you dont believe me, you can search candlepowerforums and there is data that supports this. And no, clearly intensity is not directly dependent on voltage, but it is however dependent on current, and the only way to increase or decrease current without running a PWM is to vary the voltage. Lower voltages to the led will put less current through the chip, resulting in less light, more voltage equals more light. And it looks like you were all set from the beginning.

Im looking foreword to the results.

[ZOMGVTEK]

Ignore the new kid..been talking **** and making idiotic posts since he arrived..not even sure why a Honda Accord owner signed up for these forums anyways..

I dont understand how any one of my posts can be considered idiotic, and i would like to know how they have offended you.

Oh, and i signed up to post pics for a friend who happens to have a gram am.

[magyver]

. And no, clearly intensity is not directly dependent on voltage, but it is however dependent on current, and the only way to increase or decrease current without running a PWM is to vary the voltage. Lower voltages to the led will put less current through the chip, resulting in less light, more voltage equals more light. And it looks like you were all set from the beginning.

Im looking foreword to the results.


well, you contradict yourself.. you say the intensity isnt based on V, but then you say you need less V for less light... you cant decrease I w/out decreasing V..

and yes, you can run them w/out resistors, but if you do, i would add one extra led to help absorb some V.. generaly you should use resistors as they can save you against V fluctuations that the tranhy will produce.. i would just use a wallwort.. from a cell phone charger... the extra heat isnt gonna be jack to $.. if your worried about energy costs, just look in the room.. personaly, i woulda just got a color changing led tube, as in a underbody kit. you can find them super cheap these days.. woulda saved you the headache..

as for power, i would base it off of 12V.. if you have the source, use a cordless drill battery.. thats what i do.. works great.. then just charge it every so often..

i made a helmut like you speak of.. i have white, blue, red, green, amber into a hardhat.. used an RJ-45 female jack in the helmet for quick disconnect (ethernet style) and ran a cat5 to a radio shack project box that has a toggle switch for each color.. then ran some speaker wire as my power wire to a 14.4V makita drill battery.. lasts forever...

[onesexyga]

Thank you. Exactly the info i was looking for.

I think i am going to go with a small charger or something of the sort. It wont draw too much power, and can be unplugged. Just remember im dealing with some very anal people. These are the types who unplug desktops for an hour to save the entire 2.3 watts of power they draw when shut off. I would have gone with a premade tube, but they need to be spread out across an entire wall. I had an engineer suggest a cordless battery. Might see if i can pick one up. the cat 5 is a really good idea. it would neaten up the wiring and look pretty professional.

[onesexyga]

side wall:
http://img204.imageshack.us/my.php?image=p1010045tf9.jpg

white, one of 7 colors on the end wall:
http://img248.imageshack.us/my.php?image=p1010050rb5.jpg

light pattern close up:
http://img170.imageshack.us/my.php?image=p1010051wp3.jpg

uv, doesnt look blue in person:
http://img502.imageshack.us/my.php?image=p1010052tf3.jpg

control box (in my best ron burgandy: rich mahogany). Powered by a 9v power supply which attaches to the box via rca:
http://img136.imageshack.us/my.php?image=p1010055vc7.jpg