Hi
I am using a 7805 @1A regulator with a 100uF cap on the input pin to GND and a 100uF cap on the output pin also to GND.
From this 5V I use a 3.3V regulator to supply power to the TFT screen.
Arduino runs on this 5V with voltage divider resistors (on the data lines) to the TFT Screen.
All works ok ..until I clip my scope ground lead onto the Arduino,then the screen freezes or just change colour.
I narrowed this down to not only the scope ground lead but even a screwdriver touching the ground plane anywere on the Arduino.
Only the screen freezes or change colour the Arduino Nano is still running.
The TFT Screen is ILI9163 and data is serial.
The screen is connected to the Arduino with +- 100mm leads.
I tested with a 12V 7AH battery and still the same ,so no psu problem.
I was playing with a Arduino/voltmeter and pushed the voltage up to around 20V then the 5V regulator
on the Arduino blew-up and pushed the 20V to the Atmega and usb chip ...one dead Arduino.
That is the reason I am using the 7805 external.
This also happens when everything is powered from my pc usb cable.
Any advice on this would help,Thanks.