Ok so here is the background project that I am working on. It is an LED flashlight that will utilize the joule thief to maximize the efficiency of the flashlight. The problem I am having atm is choosing the correct power source as I will have the use conventional batteries (AA or AAA). I was just wondering if my calculations are correct for the LED portion of the circuit. I have attached a picture of the schematic and here is the numbers that I came up with. LEDs I am using a super white LEDs Vf = 3.2-3.4v @ 20mA-30mA suggest 16-18mA per manufacture datasheet. Pd = 105 mW Ok so I calculated that if I want to use 3 LEDs in series I will need about 12V and a current resistor for each leg at roughly 116 ohm or I bumped it to 120 ohms as shown. Power dissipated will be about 59.4 mW so 1/4 W resistors are fine. My question is will this work for the first part of my project as a simple LED circuit?