An H-bridge with no chip

A full H-bridge built from four discrete transistors and no driver chip. Two NPN transistors form the low side, two PNP transistors form the high side, and a DC motor sits across the two outputs on a screw terminal.

The trick is the cross coupling. When an input goes high, its low side transistor pulls that output toward ground, and the falling output switches on the high side transistor on the diagonally opposite leg. So input one drives the motor one way, input two drives it the other way, and two control signals are all you need.

Four flyback diodes, one across each transistor, catch the kick from the motor winding. A 10 ohm series resistor on the supply keeps stall current in check.

This layout leaves out the base resistors to keep the board readable, so treat it as a routing study, not a finished driver. A real build needs a base current limiting resistor on every transistor.