The easiest way is to try it with a 5V supply, if it works then you don't have to worry any further, if not then we need to get the details from the voltage regulator chip, they are normally XL1509-3.3 or XL1509-5.0 (for 3V3 or 5V respectively). If you have a XL1509 ADJ then using a voltmeter to fi...