Where to get 4.7 ohm 4.7 watt resistors?

[phook15]

For my setup im using 2 blue LED's from a Tri Cree, and based off this http://led.linear1.org/1led.wiz website, im told to use 4.7 ohm 4.7 watt capable resistors. On TCSS theres no options for those resistors though. I'm using a BB setup for the Tri cree(Not using the third one) with a 7.4 volt battery and the leds run at 1000mA.

[Silver Serpent]

http://www.thecustomsabershop.com/47...stor-P492.aspx

Wattage rating is a minimum. You can always round up, and it won't hurt anything or affect brightness.

Depending on if you're using a sound board or not, you could also wire those two LEDs in series. They'd act as a single LED with a Vf of 6.3v, and you'd get double the runtime out of your battery pack.

[NanoRex]

If you have a 7.4V battery pack, you should be wiring your LEDs in series for a longer battery life and a smaller resistor.

Why are you using a 7.4V battery pack exactly? Typically those are only used for BuckPucks or for the Petit Crouton or Crystal Focus sound boards; all of those cases shouldn't have resistors.

[phook15]

If you have a 7.4V battery pack, you should be wiring your LEDs in series for a longer battery life and a smaller resistor.

Why are you using a 7.4V battery pack exactly? Typically those are only used for BuckPucks or for the Petit Crouton or Crystal Focus sound boards; all of those cases shouldn't have resistors.

Because how else would I power two 3.47 volt LED dies? I'm using a Hasbro soundboard with the transistor and a voltage regulator

[FenixFire]

Because how else would I power two 3.47 volt LED dies? I'm using a Hasbro soundboard with the transistor and a voltage regulator

If wired in parallel you could use a 3.7. That's why he is asking. If wiring in series you would add the voltages for a Vf of 6.94v

In series...voltage regulator needed
(7.4-6.94)/1=.46 ohms .46x1^2= .46W round to .5ohm, .5W

In Parallel with 3.7, separate resistor on each die...no voltage regulator needed. Done this twice now, my sons and his friends.
(3.7-3.46)/1= .24 ohm. .24*1^2= .24W. Round to .25 ohm, .25W

In Parallel with 7.4, separate resistor on each...needs a voltage regulator.
(7.4-3.46)/1=3.94 ohm. 3.94*1^2= 3.94W

[phook15]

If I used a 3.7 volt 1400 mAh with three dies that run at 1000mA, wouldn't it drain very quickly?

[Kouri]

Perhaps, but if you're using a Tip42 transistor, you need the same voltage going to the board and the LEDs, so you can't use the 5v on the board while sending the full 7.4v to the LEDs. You'll get some odd quirks like LEDs never fully turning off and flashing whenever the swing sensor triggers. You're better off with a 3.7v cell. If runtime is an issue, rework your plans to fit an 18650 or larger into your hilt.

[FenixFire]

If I used a 3.7 volt 1400 mAh with three dies that run at 1000mA, wouldn't it drain very quickly?

Depends what 7.4v pack or 3.7 cell you use...the 7.4 is just 2 3.7v series together. An 18650 base has the same 2600mah or 18500 has 1400mah. The 7.4v pack with LEDs in parallel will waste most of its power dissipating as heat through the resistors.