Reducing 4xAA voltage for Luxeon 1 watt driver...HELP!

[CG]

I hope someone can help me, for I know not about such things! I have
a LEDSupply.com Micropuck driver for the Luxeon 1 watt LED "Star". I
must run it off of four (4) NiMH "AA" cells (1800mAh) the produce
something on the order of 5.6v (4.8v nominal).

I have a problem. Though it will run amazingly well on this set up,
the micropuck driver gets very hot only after a few seconds. I
figured this would happen. My plan was to drop the voltage of the AA
cells to the maximum operating voltage of the micropuck; 3v. However
(and here is where my limited knowledge of such things haunts me) when
I successfully drop the voltage to 3v by using a resistor (as tested
on my multimeter) the LED will not illuminate. No matter how small a
resistor I use, no light.

I have to run the whole thing on the 4.8v, because it also runs
another LED component that requires this.

How can I do this? Is there another way to drop the voltage to 3
volts so I can still run the driver/LED without overheating it? I am
pretty sure if I continue to overdrive the driver it will fail. Any
suggestions? And thanks in advance...

Chris the Caver

 

[Watson A.Name - Watt Sun, Dark Remover]

I hope someone can help me, for I know not about such things! I have
a LEDSupply.com Micropuck driver for the Luxeon 1 watt LED "Star". I
must run it off of four (4) NiMH "AA" cells (1800mAh) the produce
something on the order of 5.6v (4.8v nominal).

I have a couple of the micropucks also. They require two AA cells, or
3VDC.

I have a problem. Though it will run amazingly well on this set up,
the micropuck driver gets very hot only after a few seconds. I
figured this would happen. My plan was to drop the voltage of the AA
cells to the maximum operating voltage of the micropuck; 3v. However
(and here is where my limited knowledge of such things haunts me) when
I successfully drop the voltage to 3v by using a resistor (as tested
on my multimeter) the LED will not illuminate. No matter how small a
resistor I use, no light.

I have to run the whole thing on the 4.8v, because it also runs
another LED component that requires this.

How can I do this? Is there another way to drop the voltage to 3
volts so I can still run the driver/LED without overheating it? I am
pretty sure if I continue to overdrive the driver it will fail. Any
suggestions? And thanks in advance...

The Luxeon star takes 350 mA or .35 A, so you need a resistor instead
of the micropuck. Remove the micropuck completely (it may already be
damaged by overheating). The Luxeon Star LED needs 3.2V at .35A. You
need to drop 1.6VDC, at .35A, which requires a resistor of 4.57 ohms.
So use a standard 4.7 ohm 1 watt resistor, or use two of the radio
shack 10 ohm 1/2 watt resistors in parallel.
View with courier font

10 ohm 1/2W
Batt + o--+--/\/\/\--------+-------o + LED
| |
4 AA | 10 ohm 1/2W |
cells +--/\/\/\--------+ Luxeon Star

Batt - o---------------------------o - LED


I repeat, do not use the Micropuck, you will just burn it out, and it
is _not_ needed with four AA cells.

Chris the Caver

--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@

 

[Watson A.Name - Watt Sun, Dark Remover]

I hope someone can help me, for I know not about such things! I have
a LEDSupply.com Micropuck driver for the Luxeon 1 watt LED "Star". I
must run it off of four (4) NiMH "AA" cells (1800mAh) the produce
something on the order of 5.6v (4.8v nominal).

I have a problem. Though it will run amazingly well on this set up,
the micropuck driver gets very hot only after a few seconds. I
figured this would happen. My plan was to drop the voltage of the AA
cells to the maximum operating voltage of the micropuck; 3v. However
(and here is where my limited knowledge of such things haunts me) when
I successfully drop the voltage to 3v by using a resistor (as tested
on my multimeter) the LED will not illuminate. No matter how small a
resistor I use, no light.

I have to run the whole thing on the 4.8v, because it also runs
another LED component that requires this.

How can I do this? Is there another way to drop the voltage to 3
volts so I can still run the driver/LED without overheating it? I am
pretty sure if I continue to overdrive the driver it will fail. Any
suggestions? And thanks in advance...

By the way, I forgot to mention this. Use the two 10 ohm 1/2W
resistors that I just told you about. Put a switch on each resistor,
so that you can switch just one resistor on, and cut the brightness in
half and make the batteries last twice as long. The Luxeon stars are
hungry beasts for current, and will suck your batteries dry real
quick. So you might even consider using higher values of resistors,
like 15 or 22 ohms, for lower current and brightness but longer
battery life.

Chris the Caver

--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@

 

[Boris Mohar]

I repeat, do not use the Micropuck, you will just burn it out, and it
is _not_ needed with four AA cells.

Quote form their website:

"The LEDdynamics 2-Cell 1W MicroPuck (2009) was designed to power a single 1
Watt Lumileds Luxeon, or strings of 5mm (T 1-3/4) LEDs (see app. note) "

But I agree that he should be using only two cells.



Regards,

Boris Mohar

Got Knock? - see:
Viatrack Printed Circuit Designs http://www3.sympatico.ca/borism/
Aurora, Ontario

 

[CG]

Thank you all so much for the help. It is greatly appreciated. A few
more points and questions:

OK. I understand to ditch the micropuck. I will use straight
resistors. Can you provide me with the formulae you use to arrive at
the value? I think I understand that teh ohm you say lowers the
vltage to within range of the Luxeon.

I am using 4xAA because this is the main source for another LED array
I use. It all goes on a cave helmet. I plan on using the Luxeon for
spot illumination. Which leads me to the next question.

How much, if at all, can the Luxeon 1 watt be "overdriven" in regards
to voltage? Must it be 3.2 volts? If I wanted to squeeze a tad more
light out of it, what damage will result (other than shorter overall
life)?

Also, as an aside, how do 1/4watt, 1/2watt and 1 watt resistors alter
the circuit?

So many questions! Thanks for educating me, all of you.

CG

 

[CG]

Thank you all so much for the help. It is greatly appreciated. A few
more points and questions:

OK. I understand to ditch the micropuck. I will use straight
resistors. Can you provide me with the formulae you use to arrive at
the value? I think I understand that teh ohm you say lowers the
vltage to within range of the Luxeon.

I am using 4xAA because this is the main source for another LED array
I use. It all goes on a cave helmet. I plan on using the Luxeon for
spot illumination. Which leads me to the next question.

How much, if at all, can the Luxeon 1 watt be "overdriven" in regards
to voltage? Must it be 3.2 volts? If I wanted to squeeze a tad more
light out of it, what damage will result (other than shorter overall
life)?

Also, as an aside, how do 1/4watt, 1/2watt and 1 watt resistors alter
the circuit?

So many questions! Thanks for educating me, all of you.

CG

 

[Boris Mohar]

Thank you all so much for the help. It is greatly appreciated. A few
more points and questions:

OK. I understand to ditch the micropuck. I will use straight
resistors. Can you provide me with the formulae you use to arrive at
the value? I think I understand that teh ohm you say lowers the
vltage to within range of the Luxeon.

I am using 4xAA because this is the main source for another LED array
I use. It all goes on a cave helmet. I plan on using the Luxeon for
spot illumination. Which leads me to the next question.

How much, if at all, can the Luxeon 1 watt be "overdriven" in regards
to voltage? Must it be 3.2 volts? If I wanted to squeeze a tad more
light out of it, what damage will result (other than shorter overall
life)?

Also, as an aside, how do 1/4watt, 1/2watt and 1 watt resistors alter
the circuit?

So many questions! Thanks for educating me, all of you.

You really need to master the Ohm's Law. It is the LAW

http://www.grc.nasa.gov/WWW/K-12/Sample_Projects/Ohms_Law/ohmslaw.html

http://www.ledsupply.com/techinfo.html

You headache will be caused by the fact that the LED is not a linear device.
In other words its resistance is not constant but is affected by how much
current is flowing through it. The exact nature of that relationship I leave up
you to discover.

 

[Watson A.Name - Watt Sun, Dark Remover]

Thank you all so much for the help. It is greatly appreciated. A few
more points and questions:

OK. I understand to ditch the micropuck. I will use straight
resistors. Can you provide me with the formulae you use to arrive at
the value? I think I understand that teh ohm you say lowers the
vltage to within range of the Luxeon.

You take the battery voltage and subtract the voltage drop of the
Luxeon which is about 3.2V. You get 1.6V difference. You then divide
that by the current in amps, which is .35A. That gives the 4.57 ohms.
Use the next highest standard value, which is 4.7 ohms. By putting
two 10 ohms in parallel you will have the equivalent of a 5 ohm 1 watt
resistor. The 10 ohm 1/2 watt is a common, easy to get value.

I am using 4xAA because this is the main source for another LED array
I use. It all goes on a cave helmet. I plan on using the Luxeon for
spot illumination. Which leads me to the next question.

How much, if at all, can the Luxeon 1 watt be "overdriven" in regards
to voltage? Must it be 3.2 volts? If I wanted to squeeze a tad more
light out of it, what damage will result (other than shorter overall
life)?

Your problem is that the Luxeon star needs a heatsink to dissipate the
heat. If you mount it on some aluminum, it will handle the power
properly, without overheating. If you leave it by itself, it will get
hot, and the life will be shortened. So that's your decision.

Your other problem is that if you draw too much current from the
batteries, their voltage will drop, and they will be rapidly depleted.
So stay with the maximum rated current and you won't have problems.

Also, as an aside, how do 1/4watt, 1/2watt and 1 watt resistors alter
the circuit?

If you use a resistor of too low a power, it will burn up.

I'm listening to 60 Minutes' Andy Rooney grousing about Windows and
having to press START to shut it down. He said, "Well, what the hell
else did you think I want to shut down? The bedroom window?" LOL!!

So many questions! Thanks for educating me, all of you.

CG

--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@

 

[Michael A. Terrell]

I'm listening to 60 Minutes' Andy Rooney grousing about Windows and
having to press START to shut it down. He said, "Well, what the hell
else did you think I want to shut down? The bedroom window?" LOL!!

At least he wasn't griping about old cans of paint he'll never use
again. I quit watching "60 Minutes", because it seemed like he was
always complaining about left over paint.

 

[Watson A.Name \Watt Sun - the Dark Remover\]

At least he wasn't griping about old cans of paint he'll never use
again. I quit watching "60 Minutes", because it seemed like he was
always complaining about left over paint.

Well, the rest of the show comes before, so you can still watch that. ;-)

2 weeks or so ago he really got people upset when he talked about
something. The following week, he read a lot of comments that said
they were never going to watch 60 Minutes again. Well, they're probably
still watching, mainly because it's an excellent news magazine with
unbeatable stories.


--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@
F
o
d
d
e
r

f
o
r

s
t
u
p
i
d

n
o
t

e
n
o
u
g
h

i
n
c
l
u
d
e
d

t
e
x
t

m
s
g