Is it common that Uno clones misbehave when connected to 12v on VIN?
Is it common that Uno clones misbehave when connected to 12v on VIN


Whether it is "common" is probably unanswerable unless you do some sort of survey.

However bear in mind that clones or "knock off" boards (some of which pretend to be official ones) are built to a price. The original Arduino was already designed to be cheap. To make them even cheaper the manufacturers may well make a number of compromises. For example, some use a cheaper USB interface chip. It wouldn't surprise me if the components like the voltage regulator, capacitors, etc. are under-specified.

I see from eBay that clones are already quite cheap, possibly around $US 4.50. To compete with that, some manufacturers may be cutting back even further on the quality of components.




  I assume the solution is to either use a linear regulator wired to VIN, or a battery?


You are probably better off bypassing the on-board regulator entirely. Get a wall-wart that outputs 5V regulated. The sort of thing that might power a USB-based device. Then plug that into the 5V pin of the Uno (not VIN). In fact, virtually any mobile phone charger wall-wart will output exactly what you want. Just run a USB cable from that to the USB port on the Arduino, and there you have it! Regulated 5V power.



The other thing that could work would be to give the voltage regulator a break. Don't put 12V into it, put in 9V. Then it doesn't have to work so hard (that is, dissipate the extra voltage as heat).