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121  Using Arduino / General Electronics / Re: Question about RGB LED (In comparison to another - doesn't work) on: August 10, 2012, 10:02:24 pm
Well what I am curious to know now is, why I only need one 220ohm resistor in this configuration...  According to the specs of the LED listed above, with a 220ohm resistor on the 5v line, and 3 analog pwm grounding the individual colors, how do I calculate the total current being used (by each color, and totally), if it was a single color LED, I can easily figure this out using ohms law, but how does it work with this setup and 3 colors?
122  Using Arduino / General Electronics / Re: Question about RGB LED (In comparison to another - doesn't work) on: August 10, 2012, 06:49:39 pm
So it turned out that on this LED the RGB lines are grounded and the common is the +, looking around I found out this is achieved with a single resistor from power to led, and PWM from 3 pins as ground to each color, and this works but this brings me to my next thought...  1 220ohm resistor vs 3 (1 for each color), how do I figure out exactly using ohms law this way how much current is being used for each color?
123  Using Arduino / Motors, Mechanics, and Power / Re: motor, arduino ESC and 11.1 V Battery on: August 09, 2012, 01:28:28 am
I want to avoid using an ESC in my airplane. (Sorry my title had "ESC" in it.) I'm trying to use the Arduino's PWM pins. Would they be able to give 5V commands for an 11V motor?
You will NEED an ESC to drive an RC motor, the voltage of the motor and the voltage of the arduino have nothing to do with each other, because the ESC and Motor are powered from the main flight battery (Presumably a 3 cell LIPO since you say 11.1),  the servo connection from the ESC has 3 pins, ground, signal, and +5v (assuming you are using an ESC with a built in BEC, some do not), that +5v rail can power the arduino, it would not be 11.1v, it would be 5v, in a normal RC application this ESC connection to the RX would power the entire RX and all of the servos via the power rail built into the RC RX, the Arduino in this case IS your RX, remember that most ESC's have a 2a to 3a 5v power rail, which is enough for about 4 9g servos (typical on foam planes).
124  Using Arduino / General Electronics / Re: Question about RGB LED (In comparison to another - doesn't work) on: August 08, 2012, 01:53:32 pm
Is it that PWM just isn't putting out enough to satisfy this LED?  I did a quick google and found a few schematics of people using this LED but putting PWM on the cathode instead of the 3 separate anodes, I guess I will just have to try it and see what happens...
125  Using Arduino / General Electronics / Re: Question about RGB LED (In comparison to another - doesn't work) on: August 07, 2012, 11:20:26 pm
Wow looking at the specs I didn't realize it was such a power hog LED... It's part # 276-0028, specs are 30ma green/blue, 50ma max red, fw voltage typical is 3.5v for green/blue, and 2v typical red. (Odd how red uses less voltage but more amps?)
126  Using Arduino / General Electronics / Re: Question about RGB LED (In comparison to another - doesn't work) on: August 07, 2012, 11:15:50 pm
Was from radio shack, I have to figure out where I put the package...!
127  Using Arduino / General Electronics / Question about RGB LED (In comparison to another - doesn't work) on: August 07, 2012, 08:08:05 pm
I have a basic RGB flasher circuit I built using 3 220ohm resistors, RGB LED, and PWM pins 9, 10, 11 for RGB respectively, and of course ground.  I put in a sketch for a random color fade, and it worked great with the LED that came with the Arduino, but it isn't a defused LED which makes for crappy looking results since you can see all 3 led colors individually!  Which is great for learning, however I also bought a diffused RGB led so I decided to stick it in the circuit instead, and to my surprise nothing happened... I double checked all the connections but nothing, I then tried to connect each color individually to 5v+ directly, and nothing happened, I was rather confused, so I got my multimeter and checked each color individually, and the thing lit up, albeit not at full power.

Now my idea is that I need to go with a lower ohm resistor, but why?  Even with a direct 5v+ connection and not a PWM signal it still didn't light, I have no idea what battery this multimeter uses (I am guessing a 9v, I would have to take it apart to tell), and I can't test it on itself to tell the voltage!  But it was enough to light up the LED even through the 220ohm resistor.  I am going to try lower ohm resistors on it and see what happens. 
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