LED & Current questions

I am driving 20 x KPBA-3010ESGC-F01

(https://www.electro-tech-online.com/custompdfs/2008/07/BC817_BC817W_BC337_5.pdf)

Using a small MCU and a BC817 + 2R2 resistor, my problem is the green's appear dull (very dull) is there something I'm missing as to why they should be so dull.

Thx Steve

Scarr said:

I am driving 20 x KPBA-3010ESGC-F01

(https://www.electro-tech-online.com/custompdfs/2008/07/BC817_BC817W_BC337_5-1.pdf)

Using a small MCU and a BC817 + 2R2 resistor, my problem is the green's appear dull (very dull) is there something I'm missing as to why they should be so dull.

Thx Steve

Click to expand...

It would have been more helpful to your question to post the data sheets for the LEDs, but I'll wager a guess. You are using more than one color of LED, correct?
Probably what is happening is that the forward voltage is different for your different color LEDs, so to get the same current through them, you will need a different value of resistor; probably a bit smaller resistor for the green LEDs will make them equal in brightness to the (red?) others.