Yes I'm new to building hardware circuits (I'm a software guy). I'm trying to integrate my Arduino based circuit boards into an old A/C powered EM pinball machine. Everything was working while running the Arduino off my laptop's USB plug.
The final step was to switch the Arduino to running off power from the machine. I built a board that takes 17V AC in, runs it through a bridge rectifier and an LM317 voltage regulator to get 9.7V DC out. I then plugged the positive output to VIN on the Arduino and the other output to GND. When I flipped the switch, I got a spectacular sparking light show until I turned it off.
Looking at the board, I fried something right by the USB input jack. Odd thing is I can still upload programs to the board and run them and they still seem to work so I don't know what I destroyed.
I assume I went wrong with not calculating the correct power/amperage into the board. If so, what do I need to do to make the power correct for VIN? Also, do I need to hookup the other line from the voltage regulator to the Arduino GND? If so, does it matter which GND I use?