Modified Lux III desklamp. **PICS**

[light_emitting_dude]

So I was bored last night and was thinking of what to do with all of those Lux III stars I have laying around. I have always wanted a LED Desklamp so I decided to mod the one I have.

The mount that the original socket was on made a nice mount for the Lux III star. I spliced in a power supply that I had laying around so it is running at 3 volts/600 mah.

Works great. Here are some pics.

 

[Drewfus2101]

Nicely done. I was just looking at a cell phone charger and a desk lamp and thinking the same thing last night.

 

[light_emitting_dude]

I had a 40 watt bulb originally and I got way too hot to touch the top to adjust the light and the wife always got irritated when I used it in the morning getting ready for work.

Now its not too hot to touch and not too bright for the wife trying to sleep.

 

[clg0159]

Now thats an efficiency upgrade! I am about to do something similar with a 200lm K2 TFFC and an old cell phone charger I had lying around. Have you taken temp. readings on the star?

 

[Mr_Light]

I have modded 4-5 lamps of various types using assorted wall warts 4.5 -6 volts attached to DX 800mA constant current drivers. Seems to work fine. I mount my stars inside 1 inch copper pipe caps which serve as heat sinks.

 

[light_emitting_dude]

No actual temp readings on the star. The metal bar that it is mounted on works well and it is cool to the touch. Its only being driven at approx 600 mah @ 4.5V

I have increased the voltage to 4.5V on the power supply and it did get a little bit brighter. I think the max voltage for a Lux III star is 4.7

If it blows I have many extra Lux III stars.

Now thats an efficiency upgrade! I am about to do something similar with a 200lm K2 TFFC and an old cell phone charger I had lying around. Have you taken temp. readings on the star?

 

[Drewfus2101]

Just an FYI, I did a P4 desk lamp last night. For a power supply I used an old cell phone charger. The one I used was for a Motorola Q. On the charger it said 5V 800mA. I tested it first and turns out its constant current, so it will do 800mA and vary the voltage to get that current. So its pretty perfect for a single emitter. These chargers are pretty cheap on Ebay. The charger actually has 3 wires coming out of the plug. Just remember to solder the red and white together as the positive at the emitter.

Here is a good site for these:
http://store.everythingq.com/moto-q-wall-chargers.htm

 

[clg0159]

I just finished mine with a 5V 1A charger running through a 1 Ohm resistor powering a TFFC K2. It is surprisingly bright. I do have one concern though if someone could chime in. After a 30 minute runtime to test the heat sinking I noticed the charger jack was warm(Its encased in plastic of course). Considering this is intended to charge a li-ion batt. is the extra resistance going to fry it eventually? I don't really care as it was a throw away, but also don't want to risk starting a fire

Any thoughts?

 

[Illum]

I'm not sure if anyone still sells luxVs this day and age....I'll probably get a cree or a seoul and mod that in to the lamp fixtures I have around here.

light_emitting_dude, the reason your not feeling much heat is partially due to under-driving [or "starving"] the luxIII. Nominal voltage should be 3.7V [ranging from 3.1-4.5V]. Heat is your worst enemy, your setup should last you for many many good nights. LuxIIIs, if properly driven and heatsinked, wouldn't die so easily.

I've managed to sandwich 12 LuxIs on a massive heatsink and it works pretty well as a floodlight but oy...reading under it was a PITA. When you have one light source you have, thankfully, one shadow. 12 light sources will yield 12 shadows:shakehead. Reading lights are best kept to a single LED if at all possible

I've mounted a cree [XR-E warm] on a aluminum bar to illuminate some cabinet items and running on a Nokia charger. I'm thinking of mounting some under the bed and in my bedside lamp for those "when you need light at night but not enough to blind you" times.

Fair warning, it ain't pretty...as it turns out phone chargers don't like to be used continuously. I left my "cabinet light" for one whole day [24 hours at minimum] and I noticed through the plastic covers the charger was very very warm, warm enough to warm my surge protector. I unplugged it and it gave me a 2nd degree [blister] burn under the thumb when the prongs touched me

 

[2xTrinity]

Fair warning, it ain't pretty...as it turns out phone chargers don't like to be used continuously. I left my "cabinet light" for one whole day [24 hours at minimum] and I noticed through the plastic covers the charger was very very warm, warm enough to warm my surge protector. I unplugged it and it gave me a 2nd degree [blister] burn under the thumb when the prongs touched me

How hard was the LED being driven? Genreally LiIon chargers will be CC/CV -- that is, they will charge at some set maximum current, OR until voltage reaches the terminal charging voltage of the battery (~4.2), then switch to a constant voltage. After that, the current supplied by the charger will be gradually less and less as the cell is "topped off". In most cases, the charger will be in the CC phase for less than an hour, then after that, then power draw will gradually diminish to nothing.

Your experience tells me using something like a linear regulator to reduce current to the LED to significantly under the max output of the power supply is a wise idea. Efficiency loss won't be much as a LiIon battery isn't much over the Vf of most LEDs. A potentometer input could be included to allow further dimming.

I've managed to sandwich 30 LuxIs on a massive heatsink and it works pretty well as a floodlight but oy...reading under it was a PITA. When you have one light source you have, thankfully, one shadow. 30 light sources will yield 30 shadows:shakehead. Reading lights are best kept to a single LED if at all possible

I'm still waiting for someone to produce a uniform diffused source covering an entire ceiling, which would produce NO shadows

Seriosuly though, adding diffusion film of some sort of the 30-emitter build would help dramatically.

 

[Illum]

CREE emitter...XR-E 7060 warm white [thats all I've been told from the seller on CPFM]
phone charger: Nokia 3.5V 340ma
direct drive without a resistor, hardwired and shrinkwrapped. I bought a wall plug switch to turn it on and off

the 30 emitter ones still being planned actually. its the 12 emitter one [prototype] I've been trying to read from. Doesn't work too well and I have to engage the fan from time to time.


all bad bins [10 YA surrounding 2 Y0 bins] but I got them cheap:thumbsup:
Turned it on for 30 minutes without touching the fan switch and I can smell the aroma of melting wire insulator

until I can figure out the collect dosage of current/voltage I don't think i want to try out the 30 LED one [thankfully still on the sketchboard]
I suck at soldering, used the wrong gauge of wiring and couldn't splice them together correctly so I made epoxy "hills" to mount my wires on the heatsink

 

[clg0159]

So I guess the question is not how to cool the emitter, but how to cool the charger?

 

[Illum]

I think the question is better asked as: what chargers good for continuous operation...if its utilization is based on fixed lighting.

light_emitting_dude, hows your charger feeling?

 

[light_emitting_dude]

The chargers feels warm to the touch. It basically feels the same when the light is off.

That is the only drawback of wallwarts......they always draw current.