UNO R3 with Wifi Shield and external power supply

Hello guys

My two cards had worked perfectly until today. Connecting the usual external power supply, 12VDC (tried with two different adapters), the L led on UNO flashes quickly and the Wifi is actually dead.

Working with the USB connected to UNO and the computer, everything works fine, both UNO and Wifi.

Where is the problem?

USB provides more current than the voltage regulator connected to the barrel jack or vin. You could try using a lower voltage power supply (>= 7 V) as that means less of a voltage drop through the regulator so it will run cooler and be able to provide more current.

Thanks, I’ll try and come back here.
But it’s kind of strange… the device has worked perfectly for two months with 12V. As the supply gives power to LEDs too, it’s better I give power through a regulator then, like a 7805 or 7809 for example.

Well well...

A quick view of the UNO shows a burnt diode, called D1, protecting the external power input plug. Now I'm sure the power supply must be independent - I mean Arduino boards and the self made ones, which probably need more current.

Note to oneself: use the external power to Arduino boards only :o