Wiring diagram and resistor check please!

[Zahc Zi Phan]

11590


Hey again. I finally have a wiring diagram. I know it looks like Bantha poo-doo. I am really sorry if this is hard to follow. I tried my best to make it readable. It is my first time making one so yeah. Sorry. I did not draw in the resistors but here is a list below of what I came up with:

For 5mm RGB common cathode (crystal chamber) wired to PWM signals, each with a FV of 3.3 and run at 18ma:
Red lead 2.0v 18ma: 82ohm 1/8th watt
Green lead 3.2v 18ma: 5.6ohm 1/8th watt
Blue lead 3.2v 18ma: 5.6ohm 1/8th watt

For two 12mm AV switch LEDs, blue and green, each with FV of 3.0v and run at 20ma:
Blue LED 3.0v 20ma: 15ohm 1/8th watt
Green LED 3.0v 20ma: 15ohm 1/8th watt

No resistors for MAIN LEDs. Tri-Cree XP-E2.

[Zahc Zi Phan]

Please!? Anyone? Lol.

[sgcdialler]

Diagram looks good to me. I would have your LEDs' grounds return to the main board negative instead of the button ground, since you're going to have a lot of wires stacked there the way it is right now . All your resistor calculations look good to me. Those are actually the same numbers I came up with for my crystal chamber LED as well.

[sgcdialler]

As another thought: For your buttons, you can cut down on the number of ground wires by wiring the buttons' negative leads to each other. So, for example, run the act- to the actLED- to the aux- to the auxLED- straight to the ground pad on the board. That way you only have one ground line going from the buttons to the board. It should all be the same, electrically, as what you have in the diagram, just much more efficient in terms of space. If your 5mm LED is positioned properly, you could probably get away with splicing its ground into that chain somewhere as well.

[Zahc Zi Phan]

Very interesting... Wire switch LED negatives AND act negatives all together and return them with ONE wire huh... Hmm. Sounds very efficient. You sure it will work like that without an issue? Even just wiring the Act negatives together and LED negatives together would save space. Would turn four wires into two. But one would be even better...

[sgcdialler]

From an electrical stand point, wiring 5 ground wires to one pad is the same as wiring all 5 points in a daisy chain. It would be a very different story if you were running the positive leads, since you would have to deal with the voltage drops and series/parallel issues. But all the electricity has to go back to the same place anyway. Another way to think about, if it helps you feel a little better about it, is that any stray electricity, say from a button press, isn't going to affect the other components (the other button and LEDs)--the other button breaks its circuit anyway, so the rogue electrons can't flow through there, and LEDs only work in one direction, like a one-way valve.

[Zahc Zi Phan]

Ahh. Yes that was my next question, possible backflow. Doesn't sound like it will be an issue. Thanks!

[sgcdialler]

Now I'm really thinking about it though, it may be a good idea to check with Erv on that, to make sure any power from the LED isn't going to run "backwards" through a button into the processor on the board... hm. I'll ask on FX and see what he has to say... Is there anyone here that could provide insight on this? Obviously I think it's all the same, but the last thing anyone wants is phantom current going into the processor and frying it! I've had to have two processors replaced because of that kind of thing O.o

[Zahc Zi Phan]

Haha you know maybe I'll just keep the types of negatives separate. Lol.

[sgcdialler]

It's a curious little problem isn't it? lol