Actually you are not correct on this. A standard LED typically has a forward working voltage of anywhere between 1.8 and 3 depending on the color. Unless your 10mm LED's have built in resistors, 9V will instantly burn them out. There are lots of LED calculators available online to figure the proper resistor value and wattage required for any LED array. Using a current limiting resistor does not bring the voltage down, it limits the amount of current that is allowed to pass thru the LED. Here's one LED calculator. http://scriptasylum.com/rc_speed/led.htmlI know these 10mm LEDs are rated at 9 volts so I'll just hook up a 9v battery to them. I may want to go 12v gel cell in the future (9v batteries are EXPENSIVE!) in which case I'll have to put in a resistor to bring the voltage down from 12 to 9. I DO NOT CLAIM to be a wiring or electric wiz. But that is a reasonably simple question to answer.