Driving an LED from an Arduino pin/TTL pin *the right way*.

Using Arduino General Electronics
6

retrolefty:

Can someone recommend a good NPN transistor for my scenario? 1mA to the base must allow 20mA from emitter to collector while saturating the transistor. Correctly stated?

A couple of popular low(ish) current npn transistors:

2N3904
2N2222A

For driving simple 20ma leds I like the 2N7000 mosfet transistors, no series base (gate) resistor needed and they are cheap.

Lefty

OK, I know I have all of these in my Jameco transistor kit. 100 of the 2N3904s, and only 10 each of the other two. I will try that out. I especially like the MOSFET idea, thank you.

Edit: The 2N7000 looks like a great part and Jameco has free shipping this week on orders of $25 or more so I picked up five hundred of them, five cents each (and some anti-static foam which normally really kills me on the shipping cost). I guess I am set for life.