Fandom > Cosplay / Costuming

Glowing tanhì?

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Ertew:
EA, thanks for advice. I plan to use fabric costume over whole body, except face which I'll paint. Mostly because of typical temperatures in Europe - one or two layers of fabric are better than thin layer of paint on bare skin. In that case hiding LEDs shouldn't be a problem. If this fail, fluorescent dots are my backup option.

I have access to enameled (magnet) wire, few SMD LEDs in 2835 size (about 3x3mm) and soldering gun. Hand soldering for single LED isn't a problem, most of LEDs survive my soldering skills. Just overall number of LEDs to solder looks ridiculously high. My estimations:

* 3 lines of dots per arm
* 3 lines of dots per leg
* 6 lines of dots over front of my torso
* 6 lines of dots on my back.
* Total 24 lines of dots.
* Each line are about 1m long.
* Each line contain about 60 glowing dots.
* Total 1500 LEDs to solder and about 100m of wire (including spare wire for extra elasticity). What do You think about that size and total number of glowing dots?

I plan to connect all 60 LEDs in line parallel without extra resistors. Not very clever but should do the job for low current. Each line should have current source set between 15mA (0.2mA/LED, night mode) and 300mA (5mA/LED, day mode). IMHO single 10 ohm resistor per each line and one or two variable voltage source (3-6V step-down dc/dc converter) for whole costume should do the job. Add 12V lithium pack and looks like complete solution.

Now I need to purchase zentai suit and start testing.

Toliman:

--- Quote from: Ertew on December 28, 2017, 02:10:17 pm ---
* 3 lines of dots per arm
* 3 lines of dots per leg
* 6 lines of dots over front of my torso
* 6 lines of dots on my back.
* Total 24 lines of dots.
* Each line are about 1m long.
* Each line contain about 60 glowing dots.
* Total 1500 LEDs to solder and about 100m of wire (including spare wire for extra elasticity).
--- End quote ---

I think that it would be really interesting. Location of all lines sounds good for me.
Do you want use really 1500 LEDs?


`Eylan Ayfalulukanä:
I'm going to guess that the number of LEDs you will need will be less than you estimate, as many of the 'lines' won't be fully 1 meter long.

LEDs are current mode devices, and have a constant voltage drop across them, determined by the diode material's bandgap. That actual voltage differs ever so slightly from LED to LED, even in the same lot. That tiny voltage difference though, can result in a large current difference between individual LEDs for a given applied voltage. So if you use LEDs in parallel, you need to have a small value resistor in series with each LED that drops 2-5% of the total applied voltage. This will help all the LEDs shine at a uniform brightness. This, BTW, is why virtually all modern LED lighting schemes use series connected LEDs. A series-parallel arrangement is also possible, and there, you need just one balancing resistor per string of LEDs. So, instead of using 60 LEDs and 60 balancing resistors, you could use 4 X 15 LEDs with 15 balancing resistors, or 5 X 12 or 6 X 10, with 12 or 10 balancing resistors respectively. The balancing resistors in such an arrangement could go on a small PC board so you don't have to have them at each LED string.

If you want variable brightness, consider using a PWM driver. Since the brightness whill change very quickly with applied voltage (unless you use larger balancing resistor values), its hard to simply use a voltage source. A variable constant source will work better. However, virtually all LED drivers I have seen are PWM, where they operate the LED at full brightness for a fraction of a second, and vary how long that fraction is to control average brightness. This creates the flicker you often see with dimmed LED lighting. Make suse your PWN frequency is high enough to eliminate noticeable flicker. Such a PWM driver is easy to implement with a device like a 555 timer driving a poweer MOSFET.

Magnet wire has some drawbacks in this application. Being solid, it will work harden with flexing. You will want to use, if you can find it, a very small gauge stranded wire, with either fine strands or tinsel construction. The size of the LED devices you have chosen to use should give you a range of choices for wire sizes, as they will accommodate larger size wire. Even so, a great deal of thought needs to be given to the mechanical layout and wire routing.

TEAgaming2154:
As for small stranded wire, buy some bulk Cat5 cable. Strip it and there will be eight wires inside, color coded, but all the same gauge. It's usually 24 AWG. Usually this cable is solid bit if you look you can find stranded.

Ertew:
Thanks for keeping eye on my project. You motivate me to finish this.


--- Quote from: Toliman on December 29, 2017, 01:19:51 pm ---[...]
I think that it would be really interesting. Location of all lines sounds good for me.
Do you want use really 1500 LEDs?

--- End quote ---

--- Quote from: `Eylan Ayfalulukanä on December 29, 2017, 03:29:58 pm ---I'm going to guess that the number of LEDs you will need will be less than you estimate, as many of the 'lines' won't be fully 1 meter long.

--- End quote ---
As my first estimates, Na'vi have about 60 slots over leg (single line) plus few more over foot. My leg (excluding foot) have exactly 1m hence scale. As You may see each dot have different brightness and few slots have zero brightness. That may save few LEDs but not many. Arms are much shorter than legs but have higher density. Let say about 50 LEDs excluding hand, 60 including. Same with torso - shorter but even higher density. Need to watch Av i HD and count dots again...
Answering to Toliman's question: I don't like the idea of solder that much LEDs but looks like I have to use at least 1000 LED for full blue costume. Maybe I should cosplay as Avatar driver? No LEDs on torso, just arms and legs  :-\


--- Quote from: `Eylan Ayfalulukanä on December 29, 2017, 03:29:58 pm ---LEDs are current mode devices, and have a constant voltage drop across them, determined by the diode material's bandgap. That actual voltage differs ever so slightly from LED to LED, even in the same lot. That tiny voltage difference though, can result in a large current difference between individual LEDs for a given applied voltage. So if you use LEDs in parallel, you need to have a small value resistor in series with each LED that drops 2-5% of the total applied voltage. This will help all the LEDs shine at a uniform brightness. This, BTW, is why virtually all modern LED lighting schemes use series connected LEDs. A series-parallel arrangement is also possible, and there, you need just one balancing resistor per string of LEDs. So, instead of using 60 LEDs and 60 balancing resistors, you could use 4 X 15 LEDs with 15 balancing resistors, or 5 X 12 or 6 X 10, with 12 or 10 balancing resistors respectively. The balancing resistors in such an arrangement could go on a small PC board so you don't have to have them at each LED string.

--- End quote ---
Thanks again. This time I know what I'm doing. I know that voltage phenomenon and I'll try to abuse it ;). If I connect all LEDs in semi parallel (wires between each should act as small resistors) and apply supply current on each end (+ on first end, - and second) I may achieve ugly effect - each LED have different brightness. That's what I want to achieve, as irregular as Na'vi bioluminescent dots.


--- Quote from: `Eylan Ayfalulukanä on December 29, 2017, 03:29:58 pm ---If you want variable brightness, consider using a PWM driver. Since the brightness whill change very quickly with applied voltage (unless you use larger balancing resistor values), its hard to simply use a voltage source. A variable constant source will work better. However, virtually all LED drivers I have seen are PWM, where they operate the LED at full brightness for a fraction of a second, and vary how long that fraction is to control average brightness. This creates the flicker you often see with dimmed LED lighting. Make suse your PWN frequency is high enough to eliminate noticeable flicker. Such a PWM driver is easy to implement with a device like a 555 timer driving a poweer MOSFET.

--- End quote ---
That's one of problems that need to be solved later. I like PWM too but that technique wasn't very photogenic. Camera can catch flickering even when eye cannot . Constant current will be better, just need to figure the right way to do that. Also DC/DC converter may be required to adept variable supply voltage (as battery discharges) to almost constant LEDs voltage.



--- Quote from: `Eylan Ayfalulukanä on December 29, 2017, 03:29:58 pm ---Magnet wire has some drawbacks in this application. Being solid, it will work harden with flexing. You will want to use, if you can find it, a very small gauge stranded wire, with either fine strands or tinsel construction. The size of the LED devices you have chosen to use should give you a range of choices for wire sizes, as they will accommodate larger size wire. Even so, a great deal of thought needs to be given to the mechanical layout and wire routing.

--- End quote ---

--- Quote from: TEAgaming2154 on December 30, 2017, 01:33:44 am ---As for small stranded wire, buy some bulk Cat5 cable. Strip it and there will be eight wires inside, color coded, but all the same gauge. It's usually 24 AWG. Usually this cable is solid bit if you look you can find stranded.

--- End quote ---
I never seen ethernet cable with stranded wire. I mean bare wire to purchase by meters. Patch cables with stranded wires are standard here, but purchasing them to salvage wires are bad idea.
I can purchase AWG37 magnet wire at local store. That wire are designed to withstand only 155*C (easy to solder through enamel layer) and fold that wire few times to achieve durability. On the other hand I can purchase AWG30 single wires with stranded core but coated with silicone (sticky) or teflone (hard to remove before soldering). Future tests needed.



But first I need to purchase zentai lycra suit. Poland stores offer me standard blue suit while Chinese for the same price can make custom fit one with few extra options like separate toes and detachable hand gloves. Waiting for replay from china, can they make tail for me.



Also new found, LEDs under lycra:

Overall effect looks great. Hope I can achieve similar effect. Ofc. I'll chose regular white LEDs, not the magic RGB, cost does matter. For 10$ I can purchase: 100 pcs Chinese WS2812 or 400 pcs white SMD 2835 from local store or 1000 pcs white SMD 2835 from china.

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