Ballin led tutu plan needs some help

without knowing more details about your particular LEDs, hard to say.
But lets assume 4 of those in series can drive 4 or 5 LEDs in a row.
So then you would need 20 or 25 of those strips in parallel to get 100 LEDs.
lets say 30mA (typical for led) per strip, 30 x 25 =750mA.

Yeah I think 4 of those batteries will likely be able to power a 100 LED dress..........
For about 1 hour!
So you need more batteries (or less LEDs) for longer runtime.

I REALLY am expecting pictures as a reward in the end, you realize that?:crackup:

200 pcs 5mm straw hat UV LED Wide Angle 1200MCD light - eBay (item 120503214986 end time May-01-11 01:46:31 PDT)

Those are the exact leds I bought.
And there will be pictures if I can get it made.

Oh, in the table it says these LEDs need 3~3.2 volts each, yeah that does explain why
three of them (~9V) run dimly on 4xAA = 6V....
So you need about 2xAA or one 14500 battery for each LED in the strip.
I think you should be OK for 4 or 5 LEDs in each strip if you use 4x 14500 batteries in that
4 x battery pack.

Then, the more of these strips you add, the shorter will the battery life be.

That should be ok.
My friends ruined about 50 leds in the learning process so I'm down to 150 anyway.
The one who claimed to know the most ruined the majority of them. Fabulous.

I'll find some of those batteries and try again later in the week.

Hey Anna, if you're really looking to flood black light you should ditch the LEDs and get some fluorescent black lights. LEDs just aren't well suited to putting out UV light, because they need a lot of power, and that power doesn't translate into much UV light. Also, most of the inexpensive UV diodes are in the 395nm range, which is more like purple rather than real, highly fluorescing black light (~365nm).

Even with the correct black light wavelength, UV LEDs just don't output much light. I've got a high-powered 10W UV LED that is right on the black light wavelength (365nm), and yet for all its power (and cost!) it really doesn't put out much light in absolute terms. On the other hand, I found a cheap-ass fluorescent black light for $5 and that thing pumps out tons of glowy black light. Fluorescent bulbs can create black light far more efficiently than LEDs, and they don't use all that much power either.

If you're thinking you'll have to strap some giant fluorescent bulb to your back, there are many "pocket" fluorescent lights, and black lights that will fit them. Amazon has a portable black light for about $9. They're only 6" long, battery-driven, and buying two would let you flood light on both sides of yourself. The bulb that comes with the Amazon light appears to be a cheap blue "black light." The blue ones aren't very good, so I would buy a better black light bulb somewhere else, for example something like this. I have not verified that this is a great bulb, but the fact that it looks dark purple rather than blue makes me think it's probably better. You could also buy the light itself direct from that site for $7; it has a 360-365nm bulb which is the best color range for black lights.

For the rest of your tutu, don't hesitate to add colored LEDs just to decorate it, but for the real black light illumination, fluorescent is really the way to go, and not that expensive either.

Tubes are big, and she need to keep the tutu floating, i suppose .....

Yes, with 4 Li-Ion 14500 batteries, you can use 4 led strips ..... also, in the auction they mention an If of 25mA, for less problems is better you keep the current under this level, so ..... 4 x Li-Ion batteries in serie gives you a maximum voltage (full charged) of 16.8V. a typical working voltage (for almost the 90% of the time) of 14.8V, and a minimum voltage (when they are almost totally discharged, just before go in protection), of 10.8V .....

You need to keep the current at maximum 25mA, for prevent diodes burning, so the max current must be calculated with the higher value ..... considering a 3V FV for meach led, you have 16.8-12= 4.8V/0.025= 192 ohm resistors (this for get the maximum possible light), but 192 ohm resistors are not normal values ..... using the 220 ohm resistors you already have, you get a maximum current of 22mA, still high enough (but this is just the maximum)

With the batteries in their "normal" working voltage (3.6 / 3.7 V), with 220 ohm you have 12mA ..... this means you have half of the maximum current, and this also mean half of the emitted light, but with 100 to 150 leds, it must not be a so big problem, is still a lot of light ..... also, this grant you a longer autonomy (battery duration) ..... with 100 leds (25 strips), your system must lit for at least 2 hours, 2 hours and half, with a set of good batteries fully charged (and anyway, you can still buy 8 cells, instead of 4, and carry the other 4 ones as spare, for change them if the first ones dims too soon)

A longer autonomy can be achieved using 18650 cells, with 4 of them that can power the tutu for at least 5 hours, but this add some work ..... they have holders for single cells only, so this end needing batteries hooked around the body, at belt level, some more work for sewing and connections, and so on.

EDIT: a DMM is just a digital multimeter

HIMNL9, marry me.

I'm going to do more work on this.

HIMNL9 said:

Tubes are big, and she need to keep the tutu floating, i suppose .....

Click to expand...

Well it's not so much for attaching to the outside of the tutu, but rather higher up on the body so the light floods down on the tutu and everything else since she should be glowing just as much as everyone else. This doesn't preclude other lights being on the tutu, but for major black lighting some 6" fluorescent tubes would go a lot further than LEDs.

Can I do them in series of 8 with the resistors and leds that I bought if I get the 14500 lithium batteries?

Not with 4 batteries only ..... you need to use 8 batteries in serie (or 2 battery holders in serie, if you prefer), then you can use 8 leds for each strip.

Ok and as far as the 14500 batteries go, do I have to get the rechargeable ones or can I just buy some regular lithium batteries?
Because these are the only options I have in town.
Energizer Ultimate Lithium AA Battery (4-Pack), L91SBP-4
Energizer Advanced Lithium Battery - AA - Li

Will either of those work?

^ no, those are not Li-Ion cells, those are normal alkaline 1.5V cells, they call them "lithium" only as brand name, but they have nothing to do with Lithium-Ion rechargeable batteries.

Li-Ion cells are 3.6V nominal (can go from 2.7V full discharged, to 4.2V fully charged) and the better ones are the so-called "protected cells", that have a small PCB on the negative pole that disconnect them in case of overvoltage or undervoltage (this protect the cells and the user ...... Li-Ion batteries can explode, literally, if overcharged, and at the same time, they get ruined if you discharge them under 2.7V)

The ones i'm using for some projects and flashlights, actually, are these ones, and, til now, they gave me no problems ..... for the recharger, i buyed some of these ones, and also them gives me no problems ..... are not "quick" chargers, but this is better for Li-Ion cells (less overheating in charging cycles)

http://www.dealextreme.com/p/trustf...7v-900mah-lithium-batteries-2-pack-blue-19626
Are these ok and do they come charged enough or do I need to buy a charger and charge them more at home before I leave?

And will they fit in these holders?
http://www.radioshack.com/product/index.jsp?productId=2062253

Yep those batteries will be fine and they will fit that holder.
I wouldn't count on them being charged when you get them so you need a charger, that's for sure.

I suppose they are ok, and they must fit in the holder you linked ..... i only suggest you to get a couple batteries extra, just in case one does not work (Murphy's law is always around, searching for victims ) ..... also, better you get a charger too, cause usually those batteries never come fully loaded, and also some can be loaded and some not.

Awesome.
I'm having a friend check a battery store in my home town tomorrow to see if I can avoid having to pay for rush shipping. If I can't then I'll order them asap. I'll get 12 instead of just 8.
I figure if I have one extra set and I have to stop and swap I'll be alright. I've got a great plan and I'm going to use a different tutu from the black one. I'm going to use a white one I made last year.
I did pick up a cheap cr2032 and tape it to an led for a test just on how the cr2032s would work. Held up behind the white tutu, the single led looked stunning all on it's own. I hope for most excellent results.

I promise pics asap.