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View Full Version : Help selecting resistors and tri led, cree xp l



Sidious_999
10-25-2015, 02:07 AM
For example, I want to use all red cree tri led, tcss says
Red Cree Part# XPEBRD-L1-0000-00901
80.6 Minimum Luminous Flux @ 350mA
Forward Voltage @1000mA = 2.59v

What does the 80.6 luminous Flux mean. I assume I put 1000mah and 2.59v into my calculator and get three resistors wiring them parallel?

Also looking at the cree xp l, tcss says

Cree Part# XPLAWT-00-0000-0000V5051 6200K Cool White
440 Minimum Luminous Flux @ 1050mA
620 Minimum Luminous Flux @ 1500mA
776 Minimum Luminous Flux @ 2000mA
1034 Minimum Luminous Flux @ 3000mA
Forward Voltage 2.95-3.25

Totally lost on what to use for mah and forward voltage in this one.

Can someone please help, just planning on stunt blades

darth_chasm
10-25-2015, 06:21 AM
Luminous flux is the measurement of perceived light. Reds will tend to be lower than other colors because the human eye does not perceive reds as bright. That's not to say the LEDs aren't bright, they're quite the opposite.

mAh is ampere-hour and is in regards to battery capacity/runtime. mA is milliamperes and is in regards to the current a component can accept. Its good to know this difference.

Yes, the numbers you mentioned are the ones you use for your resistance calculation. You'll also need the third part of that equation which will be your battery supply voltage.

Forgetful Jedi Knight
10-25-2015, 08:35 AM
This should help you figure things out:

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

Sidious_999
10-27-2015, 02:37 PM
This should help you figure things out:

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

I know about ohms law, what I do not know is why there is a range and different Luminous Flux on the white cree. Is it so I can choose how bright I want it or? Also how do I know what forward voltage to plug into calculator when it gives me a range for the forward voltage as well.

I know how to select single leds and figure it out but not this when it gives me different options and ranges for forward voltage

Forgetful Jedi Knight
10-27-2015, 02:48 PM
For the Cree XP-L, you pick the current you will be running the LED at and the rest of the corresponding values are what you will get. The Vf is a relative thing - the lower the current, use the lower end of the Vf range, and the more current, use the higher end of the range.

Sidious_999
10-27-2015, 03:16 PM
For the Cree XP-L, you pick the current you will be running the LED at and the rest of the corresponding values are what you will get. The Vf is a relative thing - the lower the current, use the lower end of the Vf range, and the more current, use the higher end of the range.

So if I chose to run at 1000mah on a 3.7 v battery I would need a 1 ohm resistor correct?

I take it that if u choose a lower mah to run at you will have a less bright led and longer life?

jt_trouble
10-27-2015, 03:19 PM
So if I chose to run at 1000mah on a 3.7 v battery I would need a 1 ohm resistor correct?

I take it that if u choose a lower mah to run at you will have a less bright led and longer life?

Here, just use this.

http://led.linear1.org/1led.wiz

Forgetful Jedi Knight
10-27-2015, 04:09 PM
So if I chose to run at 1000mah on a 3.7 v battery I would need a 1 ohm resistor correct?

I take it that if u choose a lower mah to run at you will have a less bright led and longer life?

Yes, both are correct. Using online calculators will also tend to give you overestimated results, which might even dim your blade more, which is why I recommend doing the math yourself, which you are capable of doing.

Sidious_999
10-27-2015, 06:47 PM
Here, just use this.

http://led.linear1.org/1led.wiz

That's the one I used just wanted to make sure I was reading stuff right and wanted to double check