DC Motors Labs

So I tried the first DC motor lab (I realized I forgot the second diode but the motor still ran) - I could smell something distinctly acidic and like burning parts so I stopped - I was using a 9V battery but I'm not sure what's causing the smell so I promptly stopped. I also couldn't seem to control the speed with the potentiometer - I checked my wiring but that didn't seem to be different from the schematic?

I also attempted the second lab but something strange kept happening to my Arduino, almost like it was burning out? Whenever I plugged it in, the L light was bright but would slowly fade away. I've never had that happen before!

 I wasn't very successful this time around with the labs, halp!