raschemmel:
Fast diodes like the 1N4148 or the 1N914?
No, those can't take the current. They will blow easily. You need 1N4001 at least.
I don't understand the schematics in the pdf.
Are the 1N4001..7 fast diodes?
I do uderstand what a H-bridge is, what I don't understand is the schematics with three motors connected to the L293 instead of two, and the fact that not all the motors seem to be reversible with the driver.