[Help]Question LED Matrix

Hi,
I'm new to Arduino things. And maybe my english is not really good
Sorry in advance.

I want to ask some questions for you guys.

I plan to make a cosplay of koro sensei. A guys with a big yellow head. His color change according to his emotions. Like the picture here :

I plan to make this of a sphere with strip led.
I will make a big matrix, that I'm going to put in the sphere.
So I can make the colors with a arduino

My questions are :

  1. Is it possible to feed a matrix of more than 500 leds + a arduino with one battery??
    Or should I try one battery for the arduino and another one for the strip ?

  2. I read on internet, the ws2812b use 50-60 mA when they are at maximum. I use that to calculate the battery I need. And I found 18 A
    I think I made a mistake somewhere.

What battery I can use for this project?

Thank you

Why a battery?

I have my 5m strip running from 5V/10A AC adapter.

maximum is every LED on.

I read on internet, the ws2812b use 50-60 mA when they are at maximum. I use that to calculate the battery I need. And I found 18 A
I think I made a mistake somewhere.

Yes you made a mistake
500 * 0.06 = 30 Amps.

Using 500 LEDs inside something some one is going to put their head into is way too much.

Using those strips is the right thing to do but you have way too many.

Hi,
How big is the sphere?
Have you really worked out how many LEDs will provide enough illumination.

Have you thought of using a semi transparent sphere and putting fewer LEDs inside to make the sphere glow?

Tom... :slight_smile:

Hi,

Thank for the answers.

ieee488:
Why a battery?

I have my 5m strip running from 5V/10A AC adapter.

maximum is every LED on.

It's for a costume so I must be able to move.

Grumpy_Mike:
Yes you made a mistake
500 * 0.06 = 30 Amps.

Using 500 LEDs inside something some one is going to put their head into is way too much.

Using those strips is the right thing to do but you have way too many.

Yeah thank 30mA seems more accurate and achievable.

I say 500 but that's an estimate, because I want to do all the color with led. For the normal face all the led will be yellow

TomGeorge:
Hi,
How big is the sphere?

The sphere is 40 cm in diameter.

TomGeorge:
Have you really worked out how many LEDs will provide enough illumination.

No I don't know how many I will use.I want to be sure that it is feasible before buying the led.

TomGeorge:
Have you thought of using a semi transparent sphere and putting fewer LEDs inside to make the sphere glow?

That what I will do but I want all the color with led. So I have to cover all the inside of each half-sphere.I have draw this on paint (Best software) to show you what are my plans.

Every yellow line is a Led Strip.

500 ws2812b LEDs in a 40cm sphere will be like a second sun. It will be uncomfortable to look at. To power it with a battery will require a car battery and a high-current 12V to 5V converter.

A few high-brightness LEDs at the centre of the sphere will be enough. And because all the LEDs will be the same colour, there is little point using ws2812 LEDs. 3 Arduino pwm outputs and 3 npn transistors can drive a dozen 5mm common-anode RGB leds.

PaulRB:
A few high-brightness LEDs at the centre of the sphere will be enough. And because all the LEDs will be the same colour, there is little point using ws2812 LEDs. 3 Arduino pwm outputs and 3 npn transistors can drive a dozen 5mm common-anode RGB leds.

I want to use the ws2812 as a screen to make all the expressions except black.

Ah, I see. I apologize, I did not take your pictures from post #1 at their face value (get it?)

If you keep the brightness down, that should help with battery life and current requirements.

Yeah thank 30mA seems more accurate and achievable.

Mike said 30A not 30mA. That is 1,000 times more. How can you achieve that in a costume?

PaulRB:
500 ws2812b LEDs in a 40cm sphere will be like a second sun. It will be uncomfortable to look at. .....

A few high-brightness LEDs at the centre of the sphere will be enough.

Paul, I think he wants to stick his head in this sphere as it is a costume he wants to make.

Grumpy_Mike:
Paul, I think he wants to stick his head in this sphere as it is a costume he wants to make.

I see. I'm not sure I would want to put my head in something with 30A circuit in it. It would be very hot!

Perhaps the sphere could be worn as a hat/headgear, with the wearer able to see through a slot in the "chest" of the outfit, making the outfit appear tall and stand out.

PaulRB:
I see. I'm not sure I would want to put my head in something with 30A circuit in it. It would be very hot!

Perhaps the sphere could be worn as a hat/headgear, with the wearer able to see through a slot in the "chest" of the outfit, making the outfit appear tall and stand out.

Sorry maybe I wasn't clear .

Yes, I will put my head inside. I already done this costume with a polystyrene ball and I see through the smile.

I was first thinking to add a "video screen" but I don't really know if it exists.
That's why I thought of led strip

For example. I see some guys to that when they make deadmau5 head

This guy make something Like I want

Interesting the comment on that first video was:-

It is not for sale, and I am not making another one.

That shows how much work and skill is needed making something like this.

I was first thinking to add a "video screen" but I don't really know if it exists.

Not curved like this. You can get a flexible LED matrix based on a similar addressable LED, expensive but could cut down on the work.

adafruit flexiable led matrix

Grumpy_Mike:
Interesting the comment on that first video was:-That shows how much work and skill is needed making something like this.
Not curved like this. You can get a flexible LED matrix based on a similar addressable LED, expensive but could cut down on the work.

adafruit flexiable led matrix

Yes I have see this matrix. Very expensive

I found it cheaper. A friend uses this works properly

But my concern is what battery he uses because he says he has more than 700 LEDs.
Then 42 Amps

Maybe He use some resistor or capacitor. He don't give details

Maybe He use some resistor or capacitor.

No he doesn't that will have no effect on the current taken. At best it does nothing at worst it can damage the strip.

To keep the consumption down do not set the colours to bright values. The full current is only taken when all LEDs are set to full white.
Each colour component takes 20mA ( 60 mA for all three ) per LED when they are set to a value of 255, if they are set to 128 that will be half the current. If set to 1 they will be 1/255 of the current.

So careful control of what you set affects the current. However beware programming errors where you accidentally set the LEDs to way over what your battery can supply, you have no protection over that.

Grumpy_Mike:
No he doesn’t that will have no effect on the current taken. At best it does nothing at worst it can damage the strip.

To keep the consumption down do not set the colours to bright values. The full current is only taken when all LEDs are set to full white.
Each colour component takes 20mA ( 60 mA for all three ) per LED when they are set to a value of 255, if they are set to 128 that will be half the current. If set to 1 they will be 1/255 of the current.

So careful control of what you set affects the current. However beware programming errors where you accidentally set the LEDs to way over what your battery can supply, you have no protection over that.

Thank for your help
I will try.
I just order the matrix. For the begin, I will try without battery using a 5v adapter And after try battery

Thank again

Hi guys

I see this on the vidoe comments:

It can hold two 4000 mAh 11.1v Lipo packs which will run the head for about 2 hours. My client bought six batteries and they swap out in less than a minute. He was able to walk around Comic Con wearing the head all afternoon

This guys run with 760 leds
I will pick this baettry

And with this I know I can run 760 max

I keep you informed