Resources
TIP vs Mosfet. A more in-depth discussion of differences.
In All Different Colors. Workshop by Kobakant.
FabTextiles
Beam’s Instructable
HairIO
Building a Heat Controlling Circuit
Heat Controlling Circuit. Note: I do not recommend TIP120s for this circuit. Use MOSFETs.
ITP High Current Loads
High-Power Control: Arduino + N-Channel MOSFET
MOSFET FQP30N06 Datasheet