Does the Arduino regulate the voltage and drop it down or will each pin now provide 9V?
Does it regulate these down 5V or 3.3V depending on which pin you connect to?
Will the VIN pin provide the full voltage of your power source?
I understand each pin provides 40 mA ...
chasing lights type pattern, where one turns on, then the following one turns on as the previous shuts off
more to power Arduino as well, and, if so, how much more
Thanks for the quick reply, guys. So, just to clarify: If I plug a 9V wall wart into the Arduino, each pin will still only give off 5V. But if I come out of the VIN pin for power, I will be getting 9V
Eyes are tricked very easily. With 3 groups of LED's you see the movement, and you can even play with different duty ratios: Having either lights or "black holes" moving around (For symmetry you'd need 12 or 15 leds, though)
Just tie the series pairs to pins 2..8 and see if the brightness is sufficient.
(To be on the safe side, test a single LED in series with a 120 Ohms resistor and verify the voltage drop is about 2.5 / 2.5 and the current is ok)
So 9V on Vin will still result in the I/O pins being (about) 5V, because there is an on-board regulator that regulates the 9V down to 5V.
Fairly sure you are, but are you saying have 2 LEDs in series connected to pin 2, then 2 LEDs in series connected to pin 3, and so on until 8? So, if I have 7 sets of 2 LEDs in series, would that mean I only need to provide half of the mA? 7*20mA = 140mA + 40mA [for the Arduino] = 180mA... does this sound correct?
current = (5 - 1.7) / 220 = 15 mA
current = (5 - 1.7 - 1.7) / 220 = 7.2 mA
As for the chasing effect, if you put the pins in groups of two, or three, it would still look like a chaser, but only need half (or a third) of the pins.
It's 6V so the Arduino wouldn't have to burn much off, correct? Because, as I understand now, the Arduino regulates everything down to 5V, yes?
So you are saying just have 2 (or 3) LEDs go on at once, then the next 2 (or 3) would go on as the previous 2 (or 3) shut off and so on to create the chasing effect?