what to build with....6V lead acid battery, lux III's??

Turbo_E

Turbo_E

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Jan 25, 2005
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322
i have some stuff lying around and was looking for ideas on what to build.

i had though of using a CPU heatsink and attaching some lux III (SX1K)emitters to it and making a flood light or lantern.

problem is, the luxes only take 4.5V or so. and the battery puts out about 6.5V
I know a Fatman driver would work, but thats $ i dont have to spend :(

any CHEAP way to make this work?

Housing to be investigated later.
 
Meduza

Meduza

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Sep 28, 2005
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2 ohm resistor at input voltage 6.5 and Vf bin K (3.63v typ):

Code:
LED
Current (rms):	574 mA
Power (rms):	3.07 W

Resistor (R)
Voltage (rms):	1.15 V
Current (rms):	574 mA
Power (rms):	659 mW

Total
Power input (rms):	3.73 W
Power LED (rms):	3.07 W
Efficiency:	82.3 %

1 ohm resistor at input voltage 6.5 and Vf bin K (3.63v typ):

Code:
LED
Current (rms):	718 mA
Power (rms):	4.15 W

Resistor (R)
Voltage (rms):	718 mV
Current (rms):	718 mA
Power (rms):	515 mW

Total
Power input (rms):	4.66 W
Power LED (rms):	4.15 W
Efficiency:	89 %

or in short:

2ohm, ~3w, ~575ma, 82% effecient
1ohm, ~4w, ~720ma, 89% effecient
 
Turbo_E

Turbo_E

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Messages
322
1 ohm, how many watts? or do i just ask for a 1 ohm resistor? I'm stupid. sorry.

thanks guys
 
B

bexteck

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Jun 23, 2005
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Turbo_E said:
1 ohm, how many watts? or do i just ask for a 1 ohm resistor? I'm stupid. sorry.

thanks guys

Most of the common resistors out there can handle up to 0.5 watts. From the numbers Meduza posted, with a 1 ohm resistor, you are dissipating 659mW or 0.659 watts in the resistor. With a 2 ohm resistor, you are dissipating 515mW or 0.515 watts. With either resistor, you are over the 0.5 watt limit, which means possible meltdown of the resistor. You can either look for resistors which are rated for 1 watt or higher, or you can use several 0.5 watt resistors to dissipate the power. The formulas for series and parallel combinations of resistors are below.

Series: Equivelant resistance is the sum of the resistor values.

Parallel: Equivelant resistance is the inverse of the sum of the inverses of the resistances. (If R1, R2, R3 are resistor values, equivelant resistance is ((1/R1)+(1/R2)+(1/R3))^-1


Hope this helps

-Blake
 
Last edited:
shiftd

shiftd

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How about LM317 linear regulator? the overhead of >1,5V is enough to set the system, and you get constant current, adjustable with external resistor too :D
 

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