Help with power calculations

Components & Accessories Power
1

I’m new to working with Arduino but i’m a programmer by trade and understand most of what’s going on with the modules and such. Where I need help is in learning how to deal with the power. For example, right now, I’m planning out a project that with a flip of a switch will move between an FM radio and a security mode. Between the LEDs I have planed for displaying volume output (six in all), plus a handful of LEDs associated with the security mode (sense sound and motion), I think I have a total of 19 LED’s, six of which will be the micro-LEDs. I have two questions, when it comes down to it.

  1. Do I need one or two arduino units to do all of this?

  2. Is there a tutorial, document, etc that can teach me how to understand what resistors and such I need to power everything? I have seen the formula to calculate what an individual LED needs - taking color into consideration and the LED specs, but when I have all these different LEDs, assuming power via DC power supply plugged into the wall (here in the US), I don’t know limits of what I can draw, how to figure all that, etc. I want to figure out how to do all the math and schematics myself. I’ve checked out many tutorials but can’t find anything on power.

2

Each LED needs an appropriate resistor. Add up all the current draws to get the total.

Keep in mind that you should not draw more than about 20 mA from any one I/O pin.

3

If each LED is on a different Arduino pin then what is the baseline number coming from the Arduino? And is it the same, regardless of the number of LED’s I’m using? I guess I’m asking how many volts is the Arduino unit giving me to work with. FOr example, if it’s 12V, and I have two LEDs connected in parallel off one pin, how is that different to calculate if I have two LEDs but each going off a different pin? I’m used to working with signal flow as it relates to audio but with electrical, there is a lot more math. lol