I'm an arduino and electronics newbie and I'm planning to try a dc motor pwm drive. I've seen schematics putting the protective diode (reverse biased) in parallel with the dc motor and other putting it between collector and emitter of the switching transistor (such as in earthshine design beginner guide to arduino).
AFAIK the first one should protect both transistor and arduino while the second (anode on E and catode on C) should protect the transistor.
Which is the right way to go?
Thanks!
I would always place the diode across the motor not the driver. That way you cut off the problem at source. However, topologically they are the same thing assuming the the power supply has low impedance.