transistor-driven LEDs circuit in a 5*5*5 LED cube

Other Hardware LEDs and Multiplexing
1

Hello,

I've just finished my long-term project which consists of making a 555 LED cube controlled by Arduino Mega. Unfortunately, there must be a mistake in my circuitry bcs I dont seem to be able to light even one LED out of the whole CUBE. I tried several LEDs randomly but couldnt turn on any. I am certain about my code and I multi-checked my wiring for electrical shorts, soldering, etc.

So it seems only two things might have gone wrong.

  1. there is a mistake in the wiring logic (I am quite new to transistor sourcing and sinking, might be a mistake in my Maths also)

  2. Multimeter doesnt indicate connection across the resistors (but I have no idea why, bcs it is mechanically connected for sure and the resistance is not so high not to indicate connection)

To sum up, I would greatly appreaciate if someone could check my circuitry and do the Maths (which is really simple). I honestly tried hard to find the problem, might be shame really that I couldnt figure out what was wrong but I have no more ideas.

Thanks a lot to all of you,
Mike

2

Mike
What chip are the cathodes connected to ULN2803A? what is the forward voltage and current rating of your Leds?

Check this out http://4.bp.blogspot.com/-lTPdhKCwPUM/TcYu7VOOwBI/AAAAAAAAAHc/hoKKTGFarNM/s1600/atmega-matrix-display-circuit.GIF
Don

3

In your pic you show "ARD GND" and 12V battery "-".
Are they connected together or not?

4

@ Frisky: yes, it is ULN 2803, sorry, I omitted that. LEDs are rated 1.8 V, 20 mA.

@ Runaway Pancake: yes they are interconnected

Mike

5

Have you tried a test without any arduino I/O?
With the +12V up/applied and 5V available:

  1. clip +5 to one 2803 input - to enable one column
  2. touch +5 to each UDN2981 input, one at a time, to see that each LED in that column lights.
6

Mike here is a nice video I found using that chip to source Experiments 5.3: 8x8 LED Dot Matrix Display Tutorial (Red/Green Common Anode) using the Arduino - YouTube
I would try what pancake said. Drive one pin on the source hi and the uln2803 the hi and see if you could manually turn them on. I really done see a issue with how you built the circuit. I don't have any source drivers to built it. I've used the uln2803 for all sorts of things.
Let us know what you find. I'm thinking about making a cube they are amazing to watch!
Good Luck
Don