Thank you very much for the detailed information, this is perfect! It makes so much more sense now! I looked at the 150ohm resistors on Jameco, but there are 1/2 watt and 1/4 watt. How do I know which to choose based on the above application?
Ultimately, I would like to run 3 kits off of one output to start with, but if I were to build something custom like the series LED link above, what would be the maximum number of LEDs I would be able to power from that 4.5V DC?