Right, I followed 98formula's steps, and the regulator wouldn't give 5V even in a little test circuit. So I reassembled my power supply with a fresh regulator, and the extra cap and larger cap recommended by kchriste, and I now have 12V for my switching module and a nice steady 5V for my motor. Thanks guys.
I've seen that two-diode rectification solution for centre-tapped transformers in textbooks, I'll give it a try in my next project.
I've seen that two-diode rectification solution for centre-tapped transformers in textbooks, I'll give it a try in my next project.