NOTES

This is what I call a sketch of some good robot bones. The functionality of the two microswitches is clarified in the program code link below. Check out the video also, for clarity. The 754410 is a classic and must be mastered by any novice roboticist.
The video illustrates some very basic reactions. The motors are rated 24VDC. At 12VDC they are a bit sluggish.

SN754410 DataSheet

PBasic Program

Relay contacts rated at
5A 250VAC
Relay coil 5VDC

Note the NPN and
Clamping diode

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H-BRIDGE with a 754410 IC

VIDEO