Chinese Arduino Uno clone can permanently damage your USB port

Hi all,

I needed an Arduino Uno with crystal for the ATmega chip for Udo Klein's DCF77 library as this works only with an Arduino using a crystal for the ATmega chip. The official Arduino Uno has a crystal but it is used for the USB chip, not the microcontroller.
I have found one, but I didn't look to the details.
See attached picture. I have one of these from Malaysia. It is exactly like in the picture. Be aware that the USB +5V (USBVcc) is directly connected to the Vout of the AMS1117 5.0 voltage regulator, that means if you are connecting both the external power and the USB you are feeding back power from Arduino clone to your PC or laptop and you CAN PERMANENTLY DAMAGE YOUR PC OR LAPTOP. There are some chips missing: the power diode D1, the T1 MOSFET (FDN340P) is missing, the comparator U5A (LMV358IDGKR) is missing.

Best regards.

UnoClone.jpg885×885 87 KB

Hope you didn't find out the hard way.
Most USB ports are fairly forgiving, but can cause a crash halfway through a lot of hard work.
A powered hub might help.
As my prototype Arduino projects tend to a be a bit iffy, one loose wire can cause a lot of grief.
I got so fed up with my bits of wire causing crashes, I eventually invested in a Cambronix powered USB hub that effectively isolates mistakes from the computer port. If time is valuable, it could be a good investment.