Ballin led tutu plan needs some help

I had thought about assembling everything and saving the sewing for last but if the soldering cools that fast I really can't see a reason not to solder and sew as I go.

Uhm, you can also do this:

cut the leds wires 8 / 10 mm lenght and pre-tin their extremities, then push them through the fabric, solder the wires at their extremities (pre-tinning also the wires, so the time for get them soldered reduces), and when they are cooled, bend the led pins against the fabric, so this also helps in keeping them in place.

If you never done soldering works, i will suggest you to do some exercise ..... like, as example, using some piece of wires, stripping them for a millimeter or two (mean, taking away the plastic without cut the inside copper ..... it's easy, when you got the hand, but can be frustrating, the first times ) ..... then pre-tin their extremities, and do exercises in soldering them one with the other (the better way for reduce the time, doing this, is to place the two pre-tinned extremities in contact (side by side, not at the tips ), and touch them together with the soldering tip ..... a second or less must be enough for melt the tin on both of them and together, then when you see it melted, without move the wire, take away the soldering iron, and keep the wires steady til you see that the tin hardened again (another second, usually) ..... repeat this til you judge that you can do it regularly also with the led pins ..... and remember, there are no "soldering manuals" that can give you the needed "manuality" for do this in a good way, only the exercise can help, with this.

Only remember that this is an operation that is better do only once ..... cause, usually, if you bend a led terminal at angle, right out from the plastic, doing it a single time, it does not cause any problem, but doing it, then un-bend and bend it a second time in the same place, there's a 90% of possibility that it break .....

So, probably the better thing to do is, mark with something the position of all the leds (for have them distanced regularly and uniformly), then decide where to pass the wires, keeping in mind to connect them in serie, 4 for each strip if used 14500 Li-Ion batteries or only 2 for strip if used normal alkaline cells, each strip with its own resistor in serie (the resistor can be indifferently at any side of the strip, or also between any of the leds of the same strip, just for not made an "bunch of resistors" in a single place) ..... at this point, you can start soldering the first strip, lefting the pins straight (being only 8 / 10 mm long, this must not cause you problems of excess of wire, once you bend them) ..... connect the strip to the battery wires, turn it on for check that all them work, then bend the led pins, fit the wires, and pass to the second strip, and so on, repeating.

I know this is a more slow way for proceed, but consider that in this way, if for any (bad) luck, you connect a led reversed or wrong, you will notice it before it's too late

Great tips.

Though I have to admit,

4 for each strip if used 14500 Li-Ion batteries or only 2 for strip if used normal alkaline cells

Click to expand...

has me a little confused.
If 4 14500 Li-Ion batteries will theoretically power the whole thing (all 100+ leds), why would it matter how many are in a series?

Cause the leds have a minimum working voltage (also known as dropout voltage), other that a current, and if you have not enough voltage, your leds does not lit.

UV leds, usually have a dropout voltage around 3V, and if you power them with less than this value, there's no current flowing in them, and no light ..... and, ofcourse, when you connect more than one led in serie, the dropout voltages will sum ..... so, 2 of them in serie, requires at least 6V, and 4 of them in serie, requires at least 12V, for work ..... then all the strips are connected in parallel with the wires coming from the batteries (and here, now, is the currents that sums, and it's a different thing)

With 4 alkaline batteries, that are usually 1.5 / 1.65 V, you can get around 6.4 / 6.6V, so you cannot use more than 2 leds for each strip ..... and also, when they discharge, the leds becomes low luminosity more quickly ..... with 4 Li-Ion cells, instead, that go from 2.7V (discharged) to 4.2V (fully charged), wih a medium value of 3.7V, you can obtain a medium value of 14.8V, with a maximum of 16.8V when they are fully charged, and a minimum of 10.8V when they are fully discharged, before the protection circuit turn them off (always better to use "protected" cells) ..... this give you the possibility to connect til 4 leds in serie, for each strip (4 of them needs at least 12V for work), and also they will work for a longer period, when the cells are discharging .....

The current, instead, is a different thing ..... in poor words, you can set the resistor values in the way that each one of the 4 leds strips adsorb around 15mA each (using Li-Ion cells and 4 leds for each strip, the resistors value is around 200 / 220 ohm (220 ohm resistors gives a little less luminosity, but it's a standard value and easy to find in electronic parts shops) and can be used 1/4W or also 1/8W (smaller) resistors, without problems ..... now, 100 leds divided in strips of 4 leds, are 25 strips, each one need 15mA, so connecting all them in parallel, they draw from the battery pack 15 x 25 = 375mA ..... the batteries can power all them, cause this is the current, not the voltage, that they have to give (a fully charged 4.2V battery CANNOT, for no reasons, give you more than these 4.2V. no matter how much you torture it p), but it can give you different currents for different times, cause this is its energy capacity ..... again in poor words, if a battery is rated, as the 14500 cells, for 4.2V - 900ma/h, this means that it can give you a maximum of 4.2V (usually, a medium value of 3.7V), AND a CURRENT of 900mA for an hour, OR 1800mA for half hour, OR 450mA for two hours, and so on (it depend from the total current that your load require) ..... so, with a theorical capacity of 900mA/h, the pack can power your leds for 900/375 = 2.4 hours (i said theorical, cause the real capacity is always a bit less, so you can expect a pair of hours of autonomy) ..... and 2 battery packs in PARALLEL, will double this value.

A different way for obtain the double of the duration is to use the two battery packs in serie, and then make strips of 8 leds, instead of 4 ..... this way, you end with 12 or 13 strips (96 or 104 leds in total), each strip adsorb 15mA. and all them in parallel adsorb 180 / 195mA, so the duration of the cells is still doubled ..... only, you need to decide yourself if for you is more easy to wire and sew strips of 4 leds or strips of 8 leds, when you are deciding where to place them on the fabric ..... maybe, if the strips of 8 leds are more easy for you to fit and sew on the fabric, this will end being the more easy way for you, for build it ..... by the way, with strips of 8 leds in serie, the resistors are better of 270 ohm, also this is a standard value, but you can still use 220 ohm (a bit more light from the leds, and a bit less duration time of the batteries, but still around 4 hours, if fully charged)

Ofcourse, for use battery packs in parallel or in serie, there's a basical rule to respect ..... batteries MUST be used always in the same group, and always charged in the same way ..... you cannot mix full charged and half charged batteries, or use part of them for something and then mix them with others ..... if you use 2 packs in serie or in parallel, the order of the batteries is ininfluent, but the batteries still needs to be fully charged all at the same level, before you use them.


EDIT: ofcourse, i'm giving these values assuming that the seller is selling you standard UV leds with around 3V of dropout ..... if they are different, a little variation in the values will solve the problem

Alright, I'm even more unsure at this point. That's just a lot to sort through to try to figure out what I need.

I hate sounding ignorant but that is kind of what I am and exactly why I'm here.

Can you just tell me how to set it up (resistors and batteries wise) if I get this exact set of leds and set them up in series of 4?
200 pcs 5mm straw hat UV LED Wide Angle 1200MCD light - eBay (item 120503214986 end time Mar-02-11 00:46:31 PST)

I know that these are the ones I'm going to buy and I will set them up in 4s.

It's 3:10AM here, but may I suggest taking a look at EL wire?

It's 12:27 here, but nah. It doesn't seem to be offered in uv.

EL wire is a bitch to drive, it needs "high" frequency and "high" voltage AC current,
plus it's not really that bright.

That last ebay link seems fine for your needs, sillly Anna.

Those need ~3Volt each according to the info in the auction, so for series of 4 LEDs,
so you will need at least 12V of battery voltage, better 13~14 volt.
So I'd suggest you get a battery holder like this:
10 PCS Battery Dry Cell Holder 2 x AA size - lead wire - eBay (item 260741749838 end time Feb-26-11 19:14:48 PST)

and some (3 or 4 minimum, 6-8 so you can have backup when the 1st set runs out of juice after a couple of hours) of these batteries:
$5.34 - TrustFire Protected 14500 3.7V 900mAh Rechargeable Lithium Batteries (2-Pack) - Batteries
You'd have to fiddle with them a bit though, to put two of them holders together in series,
so you end up with 3 or 4 batteries in series.
"3 or 4"?
Well you will just have to experiment, how well it works with either configuration!

and a charger, too:
$5.39 - Battery AC Charger for 2*14500 (100~240V/US Plug) - Chargers
$8.48 - AC Battery Charger for 2*18650/17670/18490/17500/16340/17335/14430/14500/10440 (100V~240V/US Plug) - Chargers

About how to connect everything, HIMNL9 already made a nice schematic for you, plus
he explained it in detail.

Once you have all the "ingredients" on your hands, come back, we'll help you work it out.

About the wiring diagrams, they are very easy, anyway i sketched all the 4 possible ways that you can use for wire them, trying to keep all the things the more easy possible .....

This is using 2 x "4-cells" holders and connecting them in parallel. with 4-leds strips:



this is using 4 x "2-cells" holders (like the ones linked from anselm), still with 4-leds strips:



This is using 2 x "4-cells" holders, connected all in serie, with 8.leds strips:



This is using 4 x "2-cells" holders and 8-leds strips:



As you can see, the wiring is easy in all the ways ..... the only precautions to use, placing battery packs in serie, is to use decoupling diodes and a dual-pole switch, for avoid reversing charge of batteries if for any reason one of the packs is less loaded than the other (not needed if all the cells are in serie)

Remember that the LEDs are polarized, and they need to be wired anode-to-cathode, connecting them in serie, and the end where remain a cathode must be connected to negative (and ofcourse the anode end to positive) ..... resistors have no polarity, so they can be connected in any sense and position in the strip (at start, end or in the middle, don't care).

Alright.
I'll start to gather supplies and see if I can get it done.

Would these be ideal resistors?
Amazon.com: KOA Speer 200 ohm 100ppm Thru-Hole Resistor Metal Film 1/4W 1% MF14D-F (Bag of 25): Industrial & Scientific


Ugh, jk. The shipping was like ten dollars. F that.
But are they the right sort of resistors?

Those look fine to me.
So do you have everything else already then?

Not yet. The ebay people with the leds and resistors require paypal. I set up an account and I'm waiting for it to be able to be used. Then I will order those.

I went with these resistors.
http://cgi.ebay.com/ws/eBayISAPI.dl...869931&ssPageName=STRK:MEWNX:IT#ht_4811wt_905

I just got a friend back home to get my battery packs.
http://www.radioshack.com/product/index.jsp?productId=2062253
I got two. I like the on/off switch. It's going to be super nice.

I really just have to pick out some wire and receive the leds and resistors. The tutu is almost done being sewn together. I imagine that part will be done long before all my bits and pieces come in.
And of course buy batteries.

I've not found cheap thin wire that I think I can easily use just yet. That's really the only thing I have left to really try to figure out.



I keep finding "fun wire" and non coated "artistic" wire. I assume both are unacceptable for this project.

Find some old junk computer keyboards and mice. Recycling bins, if your not afraid of dumpster diving, or PC repair shops.
Inside the cord there are several strands of thin flexible insulated wire, color varies
but usually there is a black one among them.

I doubt that I will have too much luck with that. Not that I'm afraid of dumpster diving. Just that my town is so bs small that I don't know how much luck I would have at it. I'll def give it a shot. At least the checking with repair shops bit.

I'll see what I can come up with and ask for help if I need it.

I honestly think it won't be easy to find enough scrap wire for this. I know I'll end up having to buy some for sure.
I'd rather just buy a spool of something like 50+ yards.