Help with rgb led wiring

[Plan B]

Hi all,

I need a hand with simple lighting toy I'm trying to build. It seems it should be a simple problem, but I can't seem to wrap my head around how to wire it up. I need to pack 9 rgb LEDs as close as I can to each other in a 3x3 pattern. These are 4 lead, common cathode LEDs and it makes for tight wiring so I would like to keep it simple and use as few connections and resistors as possible.

My original plan was to take 3 LEDs in a row and solder their common leads together, red to red, cathode to cathode and then solder on 1 resistor for each channel. (This would give me 3 LEDs running in parallel?) After building 2 more of the above, I was planning to solder together all the common channel leads and cathodes and wire them to there respective switches and battery. (This gives me 9 LEDs running in parallel?) Here's what the circuit looks like.

I set it up on a breadboard and started messing with the red. I used a 9v battery and three 180ohm, 1/4W resistors, 1 for each bank of 3 LEDs. The red on these LEDs has a fv of 1.8v and run at 20mA. This set up didn't work and only the first bank of 3 LEDs lit up. This makes no sense to me since the other banks were connected to the same switch and negative line as the first bank. Why would the first bank work but not the second and third? Another thing was the resistor on the working bank got very hot, very fast so I think I'll have to replace it with two 360ohm resistors in parallel as 1/4w's are all I have.

Anyways, if someone could help me figure out what's wrong with my circuit or suggest a better set up I would really appreciate it.

Cheers,
Plan

 

[Cyparagon]

Sounds like a short somewhere. Triple check your wiring and be sure none of those leads are touching things they shouldn't be.

Could you post a schematic or take a pic?

 

[Plan B]

That's weird! I had a schematic in my original post but when I came back to read your post it was gone. I logged in to reply and now I see it in the first post again. I have it hosted in my album here at LPF and haven't had this issue when posting pictures before. Here it is again, hope it works.

http://laserpointerforums.com/members/plan-b/albums/other/5287-orb.jpg

I had a very thorough search for any shorts or other issues and didn't find anything, but I will give it another look. Thanks for the reply Cy.

 

[Flaminpyro]

I tryed to look at your schematic but it wasn't there try reposting it...

 

[Cyparagon]

It's there, but the resolution is too small for me to make anything out. (1x1 pixel :crackup: )

I tried looking at your albums directly, but "This user does not have any albums to display."

Try changing your privacy settings

 

[Plan B]

Checked my privacy settings and all were set to "everyone". I then noticed that the album was set to private so I made it public. I can still only see the pic when I'm logged in though so I'm not sure if it worked. Can you guys see the schematic now in the posts above? In case you still can't I hosted it at another location also. Hopefully one of these will work now. Thanks again for all your help fellas.

http://i231.photobucket.com/albums/ee41/PIan-B/lights/ORB.jpg

I set it up on a breadboard and started messing with the red. I used a 9v battery and three 180ohm, 1/4W resistors, 1 for each bank of 3 LEDs. The red on these LEDs has a fv of 1.8v and run at 20mA. This set up didn't work and only the first bank of 3 LEDs lit up.

 

[Cyparagon]

Yeah, it's showing up now.

Each red should be running at 13mA according to the schematic. Its either a loose connection, user-error, or some of the components are dead. Check the voltages across each of the LEDs.

 

[Plan B]

After a second going over I found my problem. I originally thought my circuit design was the issue, but it turns out a failure in my bread board caused the problem. One of the metal strips on the bottom had broken between two contacts I was using. Thanks again for your help Cy.