I Just Did My First Cree Mod -- On a Torchiere Lamp!

A number of years back, we bought a number of these cheap incan "torchiere" lamps

we loved them until we got the electric bill.

Since we haven't been using them in some time,
I thought I'd try putting some Cree XR-E's in one.

The pole is in sections -- the bottom section makes a nice battery tube for 8 D cells:



I glued the XR-E's directly to the aluminum reflector with Arctic Alumina.
I cut all 4 corners on all but the most negative of the LEDs because they
are in series.



Currently direct drive, and the LEDs are barely coasting along at 400ma
with a set of partly-charged NiMH's. Obviously room for improvement
here. What sort of controller would work best for this? Continuously
variable would be a big plus.





This torchiere has since been updated with a Fatman controller and 1 more Cree XR-E LED. It is dimmable by means of a 50k audio taper
potentiometer (mounted in the original dimmer hole) connected to the Fatman.

Cool, I wonder how much electricity/money I could save if I went ALL CREE - DIY in my house?I have far too many incans/halogen spots.

Hey, that's the same lamp I've got sitting in a garage. For a REALLY simple way of powering those Crees, try running them off a plugpack with the right voltage and a high enough milliamp rating. As for varying the brightness, try something like a rheostat. I'm sure somebody can come up with a more energy efficient idea though.

Hi,
I did similar with my small halogen lamp which had before a 20w halogen bulb.
I can vary the brightness from 1% to 100% with a switching regulator (efficiency measured more than 80%). Integrated switching regulator LM2574, very easy! I just can recomment!

cheers

Nice idea

Since the bottom of the "heatsink" isn't flat, I think the heattransfer could be a problem at higher driving rates.
I would add a flat AL heatsink to/or instead the reflector and each ermitter with its own reflector.

Best regards

____
Tom

thats a pretty cool idea

how would one go about doing such a mod so that you can plug the lamp in the wall and use the original switch to dim the light?

Sweet idea! I like those lamps in the colder months as the are like mini space heaters, but I don't' turn them on in summer. I'm thinking of trying some of the DC versions like these: http://www.superbrightleds.com/bi-pin.html

Time to order a reel of x-re's

EngrPaul said:

Time to order a reel of x-re's

Click to expand...

Exactly what I was thinking

I have one of those torchieres with a slider dimmer. A dumb old bridge rectifier with the right number of LED's in series is looking like a no brainer.


Oh, BTW, nice mod Andy Thanks for the idea.

hueppi114 said:

Hi,
I did similar with my small halogen lamp which had before a 20w halogen bulb.
I can vary the brightness from 1% to 100% with a switching regulator (efficiency measured more than 80%). Integrated switching regulator LM2574, very easy! I just can recomment!

Click to expand...

Would you share your design (the circuit, I mean) with the rest of us? That is an interesting project.

Anyway, those appliances usually have halogen lamps ranging between 200 and 500W (mine has a 300W bulb). How many leds would you need to reach the same light output?

Libbs said:

thats a pretty cool idea

how would one go about doing such a mod so that you can plug the lamp in the wall and use the original switch to dim the light?

Click to expand...

The original dimmer puts out somthing like 80-110 volts AC.
Possibly it could be modified to put out a lower range of voltages,
or it could be regulated down from there.
When dimmed, they generate quite a bit of RF interference
(not sure how they ever passed Part 15), so I'd want to clean that up too.

Have a look at this and see what you think.
www.taskled.com

Oh, and :goodjob:
on that Cree XRE led mod. :bow:

Cool Andy!

I have picked up a bunch of the xitanium drivers with intent of eventually replacing all incandescent lights in my house with Cree clusters. These will all be run off the 110VAC and replace lamps that are built in and switched by wall switches.

In your lamp there, you could mount a Xitanium in the base and drive a string of 6 (actually 7) XR-E's with one of the model drivers at 350 mA. With another version, you could drive the string at 700 mA or two strings of 6 (7) in parallel at 350 mA.

I just came home from my night run with my 3x 3W LED headtorch (2x XR-E + 1x Z-Power), as I do it 2 - 3 times a week. I have to say the color temperature of XR-Es is quite cold (about 7000K?). It's perfect for outdoor lighting, better than halogen, but at home I still like warmer light - ie 3000K as a typical value for warm white fluorescents. But I hope it will not be a long time until Cree or any other company comes with some warm white LEDs with "also good" efficiency.

josean said:

Would you share your design (the circuit, I mean) with the rest of us? That is an interesting project.

Anyway, those appliances usually have halogen lamps ranging between 200 and 500W (mine has a 300W bulb). How many leds would you need to reach the same light output?

Click to expand...

the 300W bulb probably puts out about 4000 lumens (not accounting for bouncing it off the ceiling, which is why so much light is needed for these kinds of lamps) To get similar light output, you could run 20 LEDs at 3 watts each. You could also run a 55W CFL. If you don't want maximum output though, Dimming halgoen bulbs causes total efficiency for these kinds of lamps to drop from 15 lm/W down to about 3. CFL will tend to be constant, at around 60 lm/W, and LED would increase from 60 lm/W to 100 lm/W.

IMHO, the biggest benefit of LEDs is for direct lighting applications, due to the ability for those light to be focused -- such as in spotlights or task lights. Indirect lighting I believe is best accomplished by fluorescent lights.

Hi,

I used the LM2575 ("LM2574" in my first post here was a mistake, I´m sorry for that) for my desk light.
This can be used for voltages up to 35 volts and would be able to handle LED-arrays up to about 30 volts (maybe 18 CREE´s in serial) and up to 1 ampere.
I made just a modification of the standard application for the LM2575, this circuit regulates the current instead of the voltage (using a shunt resistor to put the voltage dropped over this to the feedback pin), so exactly what you need.

As soon I´m able to post the circuit here, I´ll do that.
Datasheet of the LM2575 can be seen at:

http://www.national.com/search/search.cgi/main?keywords=lm2575

The big advantage to use this switching regulator is an efficiency of more than 80% and the low cost, about a few euros per circuit (including resistors, condensators, ect.)

cheers

Hi,

I always thought it is a very stupid thing to use this 500W halogen flood lights in the living room: Most of people I know always dim the light to get the right illumination they want. But be aware: When you dim the halogen bulb only by 30 percent electrical power or so, you decrease the efficiency of the bulb down to 6lm/W or less, so you only produce heat with very little litght!
What I would be interested in is a flood light with LED´s in warmwhite (because 5500K-6500K of the CREE is a little bit "cold").
Does anyone have informations about CREE´s in warmwhite and an effiency about 50lm/W or so?
I´m looking for the "naked" emitters and not GU10 halogen replacements or so,


cheers

2xTrinity said:

the 300W bulb probably puts out about 4000 lumens (not accounting for bouncing it off the ceiling, which is why so much light is needed for these kinds of lamps) To get similar light output, you could run 20 LEDs at 3 watts each. You could also run a 55W CFL. If you don't want maximum output though, Dimming halgoen bulbs causes total efficiency for these kinds of lamps to drop from 15 lm/W down to about 3. CFL will tend to be constant, at around 60 lm/W, and LED would increase from 60 lm/W to 100 lm/W.

Click to expand...

What is to prevent us from running them in the 100 lm/W region all the time?
We would have to use more LEDs, but the cost of those is dropping rapidly,
and we have plenty of room.
Heatsinking also becomes less of an issue then, and the LEDs should last forever.

IMHO, the biggest benefit of LEDs is for direct lighting applications, due to the ability for those light to be focused -- such as in spotlights or task lights.

Click to expand...

The benefits there are quite obvious. Some of these Cree XR-E Halogen Replacement Spots
look like they'd be great for track lighting, and I have signed up for the GB. I am open to any other suggestions regarding the use of LEDs for fixed spot lighting,
particularly the XR-E with its narrow beam.

Indirect lighting I believe is best accomplished by fluorescent lights.

Click to expand...

That certainly has been true up to now. We may be very close to the tipping point.

bitslammer said:

Sweet idea! I like those lamps in the colder months as the are like mini space heaters, but I don't' turn them on in summer. I'm thinking of trying some of the DC versions like these: http://www.superbrightleds.com/bi-pin.html

Click to expand...

I do the same thing. I've got an identical looking torchiere lamp and I only use it in the Winter. I live in Wisconsin and I haven't turned on the electric heat in my apt. in over two years. Both my computer and halogen lamp are my primary space heaters in the Winter. No.. that's not a computer, it's a 250 watt space heater that does computational tasks on the side

However in the Summer it's another story. I never use the 'torch' lamp then as it turns my place into a sweatbox. I could use a CREE modified light then.

Looks like an interesting mod, though the real trick (as has been noted) is coming up with a powersupply that works off the mains and supports dimming.

I have added a 4th Cree and put in a Fatman to regulate it.
The Fatman also make it dimmable.
A 50K audio taper switch/volume control is connected to the dimmer input on the
Fatman, and is located in the original dimmer position on the lamp.

I am using the aluminum reflector itself as a heatsink for the Fatman as well as
the LEDs. A liberal dose of AA keeps the short circuits away.

The lamp also has a 3 amp fuse at the battery, just in case.