Help needed with wiring first hilt build with Crystal Focus 9

[Ibrene]

Hi all
I have finally decided to try an build my saber with sound and I have the CF 9 soundboard. My original parts I got from the Saber Shop had a BuckPuck for the Luxeon Rebel Star. Now, my question is this: according to the simple diagram from the PlecterLabs manual for the CF9, it looks like i can "just" attach the Rebel Star to the board without the BuckPuck... is that correct?

I'm assuming that the other simple wiring on the diagram are all good? Any suggestions are highly appreciated. I bought the parts in 2015.. so I guess I better start soldering...talk about procrastinating.. LOL

18107
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Regards Rene

[RavenXp]

That is correct, if you are using a sound board you don't use the buckpuck, but you will need to put on an appropriate resistor so you do not burn out the LED on accident.

[Ibrene]

Hi there, thank you for your reply. I have read the CF9 manual again and in it, it has some info re. resistor calculations etc.. but not, for what seems a super simple setup. My blue Luxeon rebel has a recommended operating current of 700mA and a typical forward Voltage of 2.95 Vf. I'm no electrician and Ohm's law and all that is unfortunately Greek to me. I have found some java script calculators on the internet, but I'm not sure if Im doing it right. My battery is a 900mAh 7.4V one. Can anyone direct me to where I can plug these numbers into a calculator to get a desired proper value for the resistor? Does it matter if it is soldered on the + side of the LED or the- side? Again, pardon my ignorance as I've just had a buckpuck that came with the wiring harness.. Regards Rene

[Forgetful Jedi Knight]

Fortunately, I wrote a nice guide to dealing with Ohm’s Law.

http://forums.thecustomsabershop.com/showthread.php?17109-Tutorial-FJK-s-quot-Down-and-Dirty-quot-guide-to-Ohm-s-Law

[Ibrene]

Outstanding... Let me see if this get's me into the ballpark... battery voltage 7-4 minus the Fvoltage of the Blue Rebel 2.95 = 4.45 divided by the mA of 0.7 gives me 6.3 Ohm... take the 6.3 Ohm and time that with the square root of the mA of 0.7 (0.49) times 6.3 and that gives me a wattage of 3.08 ... So I'm looking for a 6.3 ish Ohm 3 ish W resistor? ... A quick search at the local resistor store shows 5.6 and 6.8 Ohm resistors.. go slightly higher or slightly lower.. I'm thinking 6.8 Ohm 3 Watt... Am I about right on that? Thank you for the tips as always.. and I just connect it to either the + or the - wire going to the Luxeon Rebel ?

[ViperR]

Or, you can go on TCSS site and use their calculator. You just choose bat pack, LED and click Calculate. Results will be the needed resistor and also the closest one they sell.
Yours came out to 4.0 ohms, 4 Watts and their closest they sell is 4.7 ohms, 5 watts that will give you 85% of desired current.

[Ibrene]

I thank you ever so much. Brilliant

[Forgetful Jedi Knight]

Outstanding... Let me see if this get's me into the ballpark... battery voltage 7-4 minus the Fvoltage of the Blue Rebel 2.95 = 4.45 divided by the mA of 0.7 gives me 6.3 Ohm... take the 6.3 Ohm and time that with the square root of the mA of 0.7 (0.49) times 6.3 and that gives me a wattage of 3.08 ... So I'm looking for a 6.3 ish Ohm 3 ish W resistor? ... A quick search at the local resistor store shows 5.6 and 6.8 Ohm resistors.. go slightly higher or slightly lower.. I'm thinking 6.8 Ohm 3 Watt... Am I about right on that? Thank you for the tips as always.. and I just connect it to either the + or the - wire going to the Luxeon Rebel ?

If you just have the one die, you won’t need a resistor because there is a voltage regulator on the main pads. When calculating the resistor, you always round UP, not down.

[Ibrene]

Now I'm confused.. OK, so i have only ONE LED (blue), so when you say " there is a voltage regulator on the main pads" that you are saying is that the Crystal Focus 9 has a voltage regulator and I will NOT need a resistor... as per the picture form the CF9 manual? If you could clarify this, it would be great. I'm unfortunately not yet "hip with the lingo" so I'm assuming "main pads" in this context means the CF9. Cheers Rene

[RavenXp]

you don't 'technically' need it since there is a voltage regulator (it basically controls how much power goes to the LED) but seeing as that regulator can push out a max of 3A, and most likely the max load your LED can handle is 1A, you could very easily accidentally blow the LED with the incorrect config settings. So the resistor in this case is just a protective measure to prevent an overcurrent situation to the LED.

[Forgetful Jedi Knight]

Now I'm confused.. OK, so i have only ONE LED (blue), so when you say " there is a voltage regulator on the main pads" that you are saying is that the Crystal Focus 9 has a voltage regulator and I will NOT need a resistor... as per the picture form the CF9 manual? If you could clarify this, it would be great. I'm unfortunately not yet "hip with the lingo" so I'm assuming "main pads" in this context means the CF9. Cheers Rene

Correct. The CF 9 has a voltage regulator attached to the main LED pads (see manual). Since you only have one LED, you attach it to those pads.

@RavenXP, just because it’s “capable” doesn’t mean it actually does. Also, he says he has a 7.4V power source, and those tend not to have a large amperage output.