Need help figuring out how to wire a Nano Biscotte

[zharrhen]

I've been looking into how to wire up a nano biscotte since the electronics kit I bought is pretty awful and not at all what I'd expect from something I spent $100 on and after several hours of confusing myself I figured its better to ask for help than get it even more wrong than I probably already have. Here's what I've been able to figure out so far:



The thing that I have absolutely no understanding of though is resistor values. I've looked around and I saw how to do it but the LED I want lists things like forward voltage and amps and I dont know what to do with that. From the store page:

Green Cree Part# XPEBGR-L1-0000-00G01
130 Minimum Luminous Flux @ 350mA
Forward Voltage @1000mA = 3.7v

White Cree Part# XPEBWT-L1-0000-00F51
266 Minimum Luminous Flux @ 1000mA
Forward Voltage @1000mA = 3.15v

If someone could help me understand what this means and maybe look over my wiring diagram to make sure it wont catch fire I'd really appreciate it.

[cvsickle]

You have to use something called Ohm's Law. Google it for more information.

I think of it like this:

Your source (battery) is a 4.2 volt source (at Max charge). Your sink (LED) will take up a certain amount of that voltage (3.15v for example with white). You need a resistor to take up the remaining voltage (4.2 - 3.15 = 1.05v).

You also need to consider how much current you want to travel through the LED and the resistor (1000mA or 1A for the XPE-2 LEDs).

Ohm's law helps you determine the resistance that you need to apply to get the desired voltage and current.

(V_source - V_sink)/Current
(4.2-3.15)/1 = 1.05 ohm

The 1 ohm 5w resistor from the custom saber shop would suffice for the white. I always prefer to use a 5w resistor on the LED dies for the blade LED, just to be safe.

http://www.thecustomsabershop.com/1ohm-5w-resistor-P12.aspx

You'll have to do the same calculation for the greens.

[Doaln]

A few things; you don't need any resistors on those Green LEDs; they run at 3.7v and the battery is the same. The slight overcharge won't hurt either. This calculator is useful for determining resistors. http://led.linear1.org/1led.wiz?VS=3.7;VF=3.15;ID=1000


You also do not need the Power Extender. The Power Extender is used to control three different diodes; since you have two Green, you can join them both to L1 and the white to L2. This simplifies the wiring and is cheaper. You can, of course, use the Power Extender if you want, but it is largely very unnecessary in your configuration.

I recommend watching Shameem's tutorial  TUTORIAL - Nano Biscotte v4 Sound Install on SaberForge Lightsaber - YouTube

[Seth Skywalker]

Good choice on the Nano!   
I will, however argue what others have said. ALWAYS use resistors, to stay on the safe side. For the green a 0.47 ohm resistor is what I used for the green on my Nano biscotti.

[K-2SO]

I agree. I always teach using a resistor. It doesn’t matter how small it is, one is a VERY good idea.

[zharrhen]

Thanks for all your help, I thought something was wrong when I saw that i didn't need a resistor for the greens so its nice to have some confirmation that I was right. Using everything you've helped me with I've come up with this new wiring diagram, does this look right?

[zharrhen]

I ended up getting a power xtender board anyways because I've never soldered onto a circuit board before and I'd feel better if i had a 7 dollar board to practice on before I went in for the 70 dollar one

[Jediseth]

You can do it! Once you’ve soldered a Nano the other boards come pretty easy. I did one Nano over a year ago and then jumped to Prizm. After 3 Prizms I had the diagram memorized. CF comes easy too after a few boards when it comes to basic wiring with sound. It becomes pretty standard. Once you get into SMD’s it does get a little trickier.  For me once I got past the initial fear of ruining my board it came very easy.  Good luck, I think you’ll find it to be more intimidating in the beginning than actually hard.

[Seth Skywalker]

Soldering the nano is fairly easy, I would say. My advice is, don't rush it. Some times with my lightsaber, I got so excited I started to rush things a bit. I even forgot to put the heat shrink on before soldering a couple of times! 

[zharrhen]

I got my nano biscotte and wired it up but only one of the LEDs is powering on and its making no sound. Help???

EDIT: I fixed the LEDs, I rechecked my wiring and I fried the power xtender board. fortunately I bought it for being my soldering test board and I dont need it to run my Green/Green/White setup so we're good there. still doesnt make sound and I cant find anything wrong with my soldering.

[Jediseth]

Doh and after I was saying how easy it is, dang it!

Is anything bridged? Maybe speaker pads? Sometimes one tiny little wire can cause things to not work. I usually go over everything with a loop.