I have 6 IR Emitters I want to use in a line follower sensor array. They each draw around 20 mA. Does anyone know a good model of transistor to use to control which IR emitters to turn on and off using my digital pins of my microcontroller?

 

2N3904, 2N3906, 2N2222
cheap, common, general purpose transistors will do this job.

 

2N3906 is a PNP transistor. You probably don't want to choose that.

 

Probably true. I thought the answer was incomplete if I didn't include a pnp option.