Hello, im started learning about CNC machines about 2 months ago, i bought some things and start building one.
So here i am with transformer 12v ac plugd in socket 230v i connect 4 diodes and capacitor an i got 16.2V 4A i connect it to this one: http://www.ebay.co.uk/itm/CNC-Shield-v3-board-4X-A4988-Stepper-Motor-Drive-For-Arduino-3D-Printer-Drucker-/262159827691?
and i connect this to loptop: UNO R3 Arduino Rev3 328 Atmega328p Compatible Board USB UK for sale online | eBay?
arduino works, but if i disconnect both from power, and connect them together and plug power back on loptop can't find arduino no more.
I can upload picture or so just help.. ^ ^