HelloI have an question that I cannot find the answer in Google: I connect the USB (from computer) to the Arduino and when I measure the voltage with the multimeter the Vin pin (which is the voltage directly from USB computer)No, The USB +5vdc does not connect directly to the Vin pin, study a Uno schematic. You are just reading some 'leakage' voltage on the Vin pin if your board is being powered only via it's USB cable. I read 5.19v and when I read the voltage from 5v pin (which is the voltage from arduino voltage regulator) and reads 5.6v !!!!The value of the USB's +5vdc is determined by your PC and can vary from 4.75 to 5.25 and still be within the USB standards. Your meter's calibration might be a factor in your reading of 5.6vdc, but who knows for sure? And I measured the 3.3v pin and multimeter says 3.7v!!!Again that might be a calibration error in your meter, but the value of the output 3.3vdc regulator is determined only by the regulator and will have some standard tolerance variation. How can this be possible? More output voltage than input?I've tried several computers with more voltage eg. 5.2v and the 5v pin feed even more voltage! Help me explain this!