Hey, i'm wating to drive about 20 Leds from a output on the arduino using 2 LM3914. Problem is I don't really understand the wiring or which equation relate to what. Which resistors i change and what that effects. I would rather understand than just be told if possible.
I have a 12V supply and can obveously make that to 5V if thats more practical.
Question is how do the resisots effect things? How do i know what change in voltage lights up how many LED's? Would 50% PWM from the arduino board = 2.5V?
Any help as I cant really understand the datasheets. http://www.national.com/ds/LM/LM3914.pdf