Never mind. it is caused by the kickback from the stepper. Anyway, I installed the capacitors since it is definitely the right thing to do. Cheers!
<https://lh5.googleusercontent.com/-JBoZJXEgPuk/U9GpjIJHbFI/AAAAAAAABUs/NAb6yu2si8s/s1600/IMG_0839.JPG> -- You received this message because you are subscribed to the Google Groups "ioio-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/ioio-users. For more options, visit https://groups.google.com/d/optout.
