NBv3 Test before hooking up everything

[dese]

Hello,

this will be my first build and I got my hands on a NBv3 and now I'd like to test it before soldering the LEDs and everything together. Just like it said in the "TROUBLESHOOTING -- General Theory of Operation":

you should start with the VERY BASICS. In this case--a speaker and batteries is the right beginning. You don't even need to solder in the cells yet--just touch the + and - leads from the cells to the appropriate CF battery leads and see if you have a boot sound. You should NOT change the SD card configurations yet! LEAVE IT ALONE.

But everyone here always lets their wiring get checked with resistor and all which makes me a bit confused. Can I really just put the speaker at the NBv3 and touch them with the wires coming from the battery (at the right place of course)? I couldn't find any infos aboout this in the Users Manual. There also are only finished wiring diagrams.

[Sorry if that's a dumb question in terms of electronics but I'm afraid of killing my NBv3.]

[NanoRex]

Yes, if you wire up the speaker and touch the power leads to the board, you'll get the boot sound, which is a good way to make sure everything is working. If you change the SD card contents, you might incorrectly format it, which would make troubleshooting difficult if you haven't yet verified that the board works properly. This isn't absolutely necessary to do first as it's very unlikely that there will be something wrong with your board when you first get it.

[dese]

Thank you! Then I'll try this out first. :>

[SPACEMONKEY1]

dese, I ran one tonight. Here's the link to my post:

http://forums.thecustomsabershop.com/showthread.php?19653-NBv3-Bench-Test&p=254907#post254907

[dese]

Perfect! Thank you~! I'll test mine now, too, hope it works just as well.

[dese]

Ok, so I've tried it and it was ok. Had some problems with loose contacts because I didn't want to solder it yet.
And since I didn't have a switch, turning the thing off again didn't work, but I guess that all will be solved once everything is soldered and all.

[dese]

Ok, so this might sound like a really dumb question, but I've read many tutorials now and there's almost everytime one thing that bugs me. So today I've read the Misinformation: Corrections Thread (http://forums.thecustomsabershop.com/showthread.php?3286-Misinformation-Corrections) and there was it again:


I have _____ do I need a resistor?!?! NO!!! Where does this come from. If you bought something better why would you use a plain old $2 resistor? Drivers replace resistors. Have a soundboard? Other than a Hasbro throw the resistor out the window!
This makes it sound as if I with my Nano Biscotte V3 (which is a soundboard as far as I know) wouldn't need a resistor. Yet, even in the manual all wirings require a resistor for the LED. Do I miss something here?

[Greenie]

Don't dwell on this subject. Use ohms law and resistor each die seperately. Even if the values are nominal, it's considered good practice and saves popping your LEDs :)

[NanoRex]

That is a very old thread which hasn't been updated for new technology. The blank refers to an LED driver. These are used to regulate the current drawn by the LED so that no resistor is needed (and there are other advantages as well). If you're using an LED driver or a soundboard with one equipped (CF or PC) you will not need a resistor. NB does not have one, so you will need resistors.

[Silver Serpent]

The important part of your quoted statement is this: "Drivers replace resistors."

If you have an LED driver, then you don't need a resistor. The Petit Crouton and Crystal Focus boards have LED drivers built in. The Nano Biscotte does not.

But yeah, that thread is from 2007. Lightsaber technology has advanced a bit since then. :)

[dese]

Ah, ok, thank you!
Then I'll be off calculation my resistor values. What is actually quite fun. ;p

[dese]

Finally I had some time to calculate the resistor values but now I'm quite unsure.
I want to buy two resistors for two different sabers:
One for a single CREE XP-E2 Red (2.6V at 1000mA) and another for a single CREE PX-E2 Blue (3.4V at 1000mA).
Battery is a 18650 Li-ion with 3.7V.

My calculations:
Red
R = (3.7V - 2.6V)/1A = 1.1 Ohm
P = (3.7V - 2.6V)*1A = 1.1 W
So I'd buy a 2W 1.2 (or 1.5?) Ohm wire resistor.

Blue
R = (3.7V - 3.4V)/1A = 0.3 Ohm
P = (3.7V - 3.4V)*1A = 0.3 W
So I'd buy a 2W 0.33 (or 0.56?) Ohm wire resistor.

I've read that the ohm value is the important one and the resistors listed would be closest to the calculations that I can find in an electronics shop here.
However, especially the resistor values for the blue LED seem too low. Did I make a mistake somewhere?

[Silver Serpent]

There's a 0.47 ohm 0.5 watt resistor in the TCSS store that will do the job for the blue. Your math is fine, though you rounded up a little more than needed for the wattage.

[dese]

Oh, I forget to answer here and thank you for your fast reply. I rounded the wattage so much because I couldn't find any lower watt resistor with the desired Ohm value. Unfortunately, I already ordered from TCSS. Well, I'll find something similiar in a German shop I guess.

[Silver Serpent]

You can round up wattage, it won't hurt anything. Higher wattage resistors (like the 5w and 10w) are very large, and take up a bunch of room in your hilt. That's why you don't want to go overboard on wattage. What you've ordered will still work fine.