I need a h-bridge for a motor, (say a 2-amp motor when under full load) but I don't know how to make a h-bridge with only NPN's tranistors...
also if the motor uses a max of 2-amps, but likely 250mA to 500mA under a typical amount of load,
what should the NPN trsanistors have as their amp rating if used in an H-bridge setup? (Typical & Absolute Max, Amps)
also can anyone provide me a NPN-Only H-bridge Shematic?
-Thanks-
http://www.placella.com/schematics/h-bridge_NPN-only.png
One of the requirements seems to be that you have a power rail higher than the motor drive voltage. In the schematic above (found with a Google search for: "NPN Only" H-bridge) the motors are driven with 12v and an 18v supply provides the switching current for the transistors.
You'll run a lot cooler if you use MOSFETs.
http://www.armory.com/~rstevew/Public/Motors/H-Bridges/Blanchard/
Or, you could just buy a motor shield.