TIP122 NPN Darlington transistor

The high current gain of 1000 makes it perfect for driving motors straight from a logic pin, and the TO-220 package is a breeze to bolt onto a heatsink. I've got three of them running in a relay driver circuit now and they're solid as a rock.

Swapped out a standard transistor for this Darlington in a switching circuit and the gain of 1000 made a noticeable difference in efficiency. It's handling the load without any voltage drop issues so far.

Used one to drive a small DC motor with an Arduino and the TO-220 tab made heat sinking a breeze, even under continuous load. The 1000 gain means a tiny base current switches it fully, which saved me from adding another driver stage. Solid choice for any high-current switching job.