So I am building this 8x8x8 cube where all cathodes are attached together in a layer and every anode is attached to the one above it, it forms a column however when I apply some current multiple leds light up which should not happen. For example if I apply gnd to layer 0 and touch the anode of 2nd column then that only that led needs to light up. I checked for short circuits there are nothing.
https://www.mediafire.com/file/6vvh3wkoyblpp6n/4F043E87-66BC-48A5-9486-B71A9D7C5086.jpeg/file https://www.mediafire.com/file/8bosvzeuwlh2nt3/E9E03609-75C9-44A4-8615-F7889BD4B171.jpeg/file
https://www.mediafire.com/file/8bosvzeuwlh2nt3/E9E03609-75C9-44A4-8615-F7889BD4B171.jpeg/file
Exactly which LEDs light up under the circumstances that you describe ?
Is there any pattern to the LEDs that light up if you connect to different columns and the same layer ?
What voltage are you testing the cube with ?
Did you check that every LED in each layer worked as expected before connecting the layers together ?
Please check the image and sorry about uploading it on mediafire that means you have to download the image for some reason my iPhone doesn’t let me attach pics
Can you post a simplified schematic please? (Not 512 leds)
How are you addressing 1 led? you seem to have x, y but no z.
Sorry karthyk I dont think anyone here will download pictures from an unknown source.
This is the schematic there is only x any y if you think about it the z’s are all anodes soldered together and x an y is the cathode idk if this clears your doubt maybe it might make you more confused check the schematic it should clear it up
https://pin.it/5XSUDdI
This is the schematic there is only x any y if you think about it the z's are all anodes soldered together and x an y is the cathode idk if this clears your doubt maybe it might make you more confused check the schematic it should clear it up
To select 1 Led from an xy grid requires x & y selectors.
To select 1 LED from an xyz cube requires x,y,z selectors.
in the schematic X is (say)D0-D8; from J1; Y is from J1 via a 3-8 decoder, enabling 1 led driver. Z iS from J2;
That is why you have 8 leds lighting up. Or you should have.
Please read step 6
We don’t need x,y,z selectors
OK Karthyk, you know best. I'm out.
To select 1 Led from an xy grid requires x & y selectors.
To select 1 LED from an xyz cube requires x,y,z selectors.
in the schematic X is (say)D0-D8; from J1; Y is from J1 via a 3-8 decoder, enabling 1 led driver. Z iS from J2;
That is why you have 8 leds lighting up. Or you should have.
johnerrington:
OK Karthyk, you know best. I'm out.To select 1 Led from an xy grid requires x & y selectors.
To select 1 LED from an xyz cube requires x,y,z selectors.
in the schematic X is (say)D0-D8; from J1; Y is from J1 via a 3-8 decoder, enabling 1 led driver. Z iS from J2;That is why you have 8 leds lighting up. Or you should have.
Ok i am sorry dude you are right I will upload the pictures maybe you will understand help a brotha out man we don't need to fight I need your help
Bump
Bumping won't do you any good if you don't supply the information needed for an informative answer.
Don't know what information we need? Well, let's put it simple: whatever is needed to recreate exactly what you did.
If you have random LEDs lighting then you have made mistakes in your wiring. You need to check every LED very carefully and make sure it is correctly wired. The mistakes are there, you need to find them. You have the cube, we don't, however difficult this is for you it's a great deal harder for us, especially with incomplete information.
I tested out some of the leds with a multimeter, the anode and cathode are connected?!? What?!?
Is it because of faulty leds or heat damage due to bad soldering job?
Maybe you had the multimeter leads touching each other, or the wrong way around. Seriously, how would we know? I for one have yet to destroy an LED by simply soldering it. The things seem to be pretty robust.
Did you remember to test the LEDs before you put them in the cube?
Hi,
Welcome to the forum.
Please read http://forum.arduino.cc/index.php/topic,148850.0.html.
Please attach your image files, the forum editor will automatically insert them into your post.
When testing with 5V on anodes and cathodes, did you use a current limit resistor?
Thanks.. Tom.... 
Yes, I have used a current limiting resistor. and i am pretty sure i haven't shorted the legs of the multimeter, like you said i made the mistake of not testing the leds before soldering them to the cube. i am using some pretty cheap leds. what i want to know is if they failed due to my bad soldering skills why do they fail as a short?
how do i prevent this from happening.
thanks,
karthy
how do i prevent this from happening.
Use a lower temperature
Use a heatsink such as pliers holding the LED lead between the LED and the solder joint
Test each LED before soldering it in place
Test each row of LEDs as you have soldered them in place
Test each cube slice as you complete them
I can say from personal experience having built built an 8 * 8 * 8 cube that the last 3 suggestions are life savers as the chances of finding 512 good ones in a pile of cheap LEDs is very small, as is the chance of you making over 1000 good solder joints
Needle nose pliers with rubber band holding the handles make great heat sinks for soldering LEDs out in the open like you did.
Paul
Paul_KD7HB:
Needle nose pliers with rubber band holding the handles make great heat sinks for soldering LEDs out in the open like you did.
Paul
Haemostats are even better
UKHeliBob:
Haemostats are even better
Strictly speaking, suture forceps are the proper tool, much broader and flatter jaw.
While they are nowhere near as good as the expensive re-sterilisable ones with carbide inserts, single use disposables are now common so if you can find a medical centre who will give you the used ones with due cleaning of course, you win! 