LED HELP

[robertlopez925]

i am doing a project where i am needing to have a white and Red led on the same power source. But every time i connect them together the red led will work but not the white led will not. Can some one explain why this is happing and how to fix the issue.

Thanks

i am using a 3v warm white led and a 3v red/green led with a common cathode   

[IanB]

Short summary of above post: use a separate current limiting resistor on each LED.

[Simon]

And White and Blue want a smaller resistor not larger because they work at a higher voltage so have less left over for the resistor.

R = (Vin-Vled) /Iled

[Corporate666]

i am doing a project where i am needing to have a white and Red led on the same power source. But every time i connect them together the red led will work but not the white led will not. Can some one explain why this is happing and how to fix the issue.

Thanks

i am using a 3v warm white led and a 3v red/green led with a common cathode

You need to give more information on how you have it connected now (a schematic), as well as what your power supply is.

[Fat]

You need to give more information on how you have it connected now (a schematic), as well as what your power supply is.
[/quote]

How are you wiring them?  If they have a vf of 3 volts each and you put them in series, you need to provide 6 volts DC and the correct current to operate each different color.  Most colors require differing amounts of current. My whites run at 1150 ma.  The reds would die at this current. (We are running them as lighting over a saltwater fish tank).

If you MUST have them run on the same supply you will need to determine the maximum vf and current for each, supply for the greatest and put something in place to limit the vf and current to the one requiring less of each.

Best of luck.
Fat