my Problem is, that I get random values from my ultra sonic sensor if my arduino is connected to any external power supply (vin port 30) on my arduino nano.
If I power up from the laptop usb port, I get consistent values.
I have tested 3 different power supplies between 7-17V and up to 2000mA. I have tested this on 2 different nano boards. Also tested with an extra 2000uF capacitor between vin and gnd
pls help if you got an idea :)