Hi guys! Full disclosure: the board I'm working with is not technically an arduino board, but it's a similar that I program with the Arduino IDE. I didn't know where else to ask and everyone here is just so clever I figured someone would be able to help (flattery will get you everywhere ;) !)
So here's where I'm at: Eventually, what I want is to have a few strings of a few LEDs, with each string switched on and off by a pin on my Adafruit feather board. The board has 3.3v logic, with 600mA peak current output, so I can't run many LEDs off of it directly. I figured I needed some transistors, so I could use the output of a pin to control LED strings powered by another power source.
I got some Pn2222 transistors and made a test circuit to try switching just one string of LEDs first. But I can't seem to get it to work!
I've tried using different pins, and using different values of resistors at the transistors base, but no matter what, whether the pin is high or low, the LEDs never light. Can someone point me in the right direction? I've attached a picture of my circuit - let me know if anything is unclear.