Controlling 104 LEDs

Using Arduino LEDs and Multiplexing
1

Hihi guys

I am a art student trying put my idea into the real world. I have a idea of controlling 104 LEDs (single color). 2 LEDs for every week of the year.

I know I need arduino bord and some shift registers, LEDs and other things.

Can someone please tell me what kind of arduino, what kind of shift(how many) I need to order.

I have LED module that need 12V Dc, Do I need some transistors to control that?

2

I have a idea of controlling 104 LEDs

Can you tell us what your definition of "controlling" might include?

3

I am up here in northern europe. In summertime we have daylight 24 hours and in wintertime we have dark 24 hours.

The artwork is 2m long, if u imagine 2m split in half, and the line is breathing/harmonic in to left and right from the middle line.

So In 21th of December every LED is on. Then it gets brighter, Two LED will turn off from the middle line every week to both ends.

So 26 weeks later every LED is off, when it is 24 hour daylight up here in north.

Does that controlling shame fill your requirements?

The dream is to dim the LEDs, to do it more detaild. But that not so important.

4

Dewalt,
The cheapest solution for your project may be charlieplexing. Take a look at this shield here:
http://www.adafruit.com/index.php?main_page=product_info&cPath=17_21&products_id=286
You can rearrange the LEDs in the formation you need. You can also address/control them individually.

5

Do you have a datasheet on the LED module?
You may need a transistor, or a transistor array (8 drivers in one package, such as ULN2803, look it up www.ti.com) may suit your needs.
Depending on the current flow needed, a shift register such as TPIC6B595 may suit your needs, also combining shift register, high current drive that can handle 12V, and with an output enable line to also support dimming (of all 8 outputs) via PWM.
Depending on your modules, you may be able to drive 2 modules with 1 shift register output, so you would need 7 shift registers (8 bits each, for 56 total).
Any Arduino would be sufficient as you really just need 4 control lines (serial_data_out, serial_shift_clock, data_output_latch, and PWM).

6

Thanks a lot for that guys.

I don´t have datasheet for the LED module, but I know it needs 12V Dc and is 0.5W.

So 2 LED is 1W/12V=833mA So I need to order 52 transistors right?

7

sorry small quesion

I am going to order those parts but I am not shure what I shuld order.

What kind of arduino, Usb arduino?
What kind of transistor and shift register?

Where is best to buy those things?

8

Yes, your math looks right.
Make sure you get logic level MOSFETs with low Rds.

9

I'll let others chime in on sources in northern europe.

10

Thanks a lot Mr.Edison

Now I have got most pice of the puzzle.