sixeyes:
magnethead794:
sixeyes:
Your LED resistors are in parallel with this one resistor.No, it's in series....
If you don't like my terminology, think about the current. You need 10mA per LED. That's 390mA through a single resistor that needs to drop the same voltage as a 150 ohm resistor drops at 10mA. The voltage dropped by the 150 ohm @ 10 10mA is 1.5 volts. Using R = V/I you get 1.5 / 0.39 which yields 3.9 ohms. You get exactly the same result, so you can consider the LED resistors to be in parallel (from an analysis point of view).
The end result is that the resistor values I've quoted are correct and if you're still having a hard time believing it, use a 150 ohm resistor instead. You won't burn it out but each LED will get about 0.5mA each. They might glow dimly but it won't be 10mA per LED that you're hoping for.
Iain
Then I may need less than half current...I just put a 150 on the power line, and it's the exact brightness I need.
When I say direct link, it implies that the primary resistor is there, but not the secondary dimming resistor.
first is 150 ohm high light -> http://i1105.photobucket.com/albums/h355/magnethead494/IMAG2105.jpg
second is direct link high light (what I want) -> http://i1105.photobucket.com/albums/h355/magnethead494/IMAG2106.jpg
third is direct link low light -> http://i1105.photobucket.com/albums/h355/magnethead494/IMAG2107.jpg
fourth is 150 ohm low light (what I want) (but the resistor got hot to the touch) -> http://i1105.photobucket.com/albums/h355/magnethead494/IMAG2108.jpg
