Converting an expensive old incandescent reading lamp into LED.

Other Types of Lights LED Spotlights
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About 15 years ago, I bought (what was at that time) a rather high end (and expensive) reading lamp for my desk. Internally, it converted 120VAC to 12VDC and used a 50W halogen bulb for illumination. I was very pleased with it for a while until CFL's came out, then I converted to them instead because Im rather energy conscious and CFL's consumed less power than incandescent bulbs. So the expensive little lamp sat in a box in my basement for the past 5 years being unused. Its actually lucky to have avoided the garbage can several times throughout the years.

Like many of you, Ive converted many of my old LED flashlights to XM-L and wound up with several LED's that were destined for the garbage can. There was one MCE in particular that delivered a very pleasing tint and I began to wonder what I could use it for. While going through boxes a few weeks ago looking for something else, I happened upon the old desk lamp. Then I found several old wall-wart transformers that I had saved and began some testing with my multimeter and MCE. I found the perfect transformer to power the MCE direct drive without overheating the LED or transformer and began surgery on the old desk lamp the next day. The new transformer fit into the cavity inside the lamp and I was able to use the stock fused connectors with a few modifications.

I initially installed a rheostat in place of the switch so I could dim it. After using the converted lamp to illuminate a few projects, I found that I only ran it at full power, so I converted it back to the original switch. Besides, the old analog rheostat is far more valuable to other projects (DD Mag conversions!) It came out of an old jet fighter and was probably the absolute best money could buy in its day.

Gutting the lamp of its old transformer, bulb assembly and wiring. Laying out the new pieces.

I drilled a hole in the top of the reflector large enough for the MCE to fit. The photo doesnt show it, but the MCE is actually sticking out well past the hole into the reflector so there are no obstructions to the beam. You can see some Fujic paste inside the hole.

Since the top of the hood was already heavily vented to allow heat to escape from the old incandescent bulb, all I needed was to build a makeshift heat sink out of copper to carry the heat from the MCE to the hood.

Here it is in my hobby room providing 100% of the light after dark. The beam is absolutely flat with no hotspots or distortions... pure flood light. The lamp moves up and down and tilts so its the perfect hobby/project/reading lamp.

It consumes far less power than the old incandescent, seems to put out at least twice the lumens, has a much more pleasing tint and runs much cooler. All that while retaining a stock factory appearance.

Measured through my P4400 KILL A WATT meter:

Before the LED transplant - 52 watts

After the LED transplant - 3.7 watts

Im glad I didnt throw the old thing away after all!

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Very cool, nice job.

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A nice warm tint makes a perfect a great desk lamp. Is that a warmer tint, or is that just camera white balance magic?

Nice mod though.

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Nice job Flash!

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Excellent .

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Very nice mod, Flashpilot! I like how it turned out.

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looks great! good job

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Very nice!

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The light in the photo is illuminating a lot of dark wood so the tint appears neutral. In actuality, the light it casts is whiter in tint than a comparable XML T6, which shows a slightly green hue. The light is best used where high contrast is needed, such as in reading or doing intricate work. It also does well as an economical bright night light.

There are many used furniture shops in town and I might set out too see what other lamp hosts I could buy to modify. Id like to have a multi-LED array. Possibly a well built heavy host with two or more gimble mounted heads so each light source could be aimed independently.

Probably the most valuable information that was gleaned from this mod is just how well copper works as a heat sink; and how far heat can travel while in thin copper.

I tried aluminum first but found that the heat would not travel the entire length of the metal strips to transmit the heat to the light head. The copper strips shown in the photo were actually slightly thinner than the aluminum ones that they replaced but conducted the full amount of heat all the way to the ends of the strips. AMAZING! The copper strips contact the light head when assembled and the whole package then becomes a large heat sink. The copper is 16 gauge roof flashing, available anywhere quality roofing supplies are sold and was advertised as being 100% copper. Ive read that very high copper content (99% or better) is very important to conducting the maximum amount of heat for sinking purposes.

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Yup! That's why I'm a fan of using big chunks of it when I can in mods :)

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Right you are! There's a recycling company in town that has huge dumpsters full of scrap copper. Guess where Im headed? Time to refine the arts of "dumpster diving".

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Cool! Nice job. I bet that doesn't strain your eyes as much as other bulb types

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Im still enjoying the heck out of this lamp, and its so useful. If only my flashlights got this much use.

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Very cool indeed.

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What kind of transformer did you use?

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I dont know what the transformer is from. I picked up several different ones at a used electronics store. The one I used is rated at 3.0V @4.0A. The actual measured no-load voltage through my DMM is 3.21V. Selecting the proper transformer requires a DMM and some testing to determine actual outputs. I brought along my DMM and a wired star mounted MC-E, paper clips and test leads to the store and tested several transformers before I bout them. A caution: if the voltage is above 4.5VDC or amperage is to high, you could destroy the LED, so test the voltage first. The labels on the back of the transformers are not precise specs. A good test LED would be an XM-L since the vF is fairly low and the emitter can withstand the abuse of +3.5A without a heat sink for a few seconds while you get a reading.

Also, keep in mind that you could potentially electrocute yourself or start a fire if you arent familiar with electronics.

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Very good advice indeed. It's one thing experimenting with batteries but AC is whole different beast.

Very nice mod. I have a similar lamp but about 1/2 the size. It ran hot as hell, but loved the tint of the bulb. I still have it in my old bedroom at my parents house.

And that wallwart in your pic looks like my LaCrosse Bc900 charger. It also puts out 3.0v.

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Measured through my P4400 KILL A WATT meter:

Before the LED transplant - 52 watts

After the LED transplant - 3.7 watts

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This is a nice find, but a bit over my head. I have the EXACT same model of desk lamp converted here. I’ve had it all apart for years meaning to convert it to LED, but lacked the know-how and I couldn’t find any layperson’s instructions on making the conversion. Can you please list the parts you used with some basic instructions using the stock switch? The reflector you drilled a hole into looks black. Is this an additional reflector beside the stock aluminum one? Thanks so much. Graz

EDIT Dec 23: Is this correct? When converting this particular lamp using the stock switch, you eliminate the low power setting. It’s only high or off. (Or you can use “high” for both sides of the switch.) You run the red(from switch) and yellow(from plug) wires through your mentioned 3.21v transformer and up to the lamp. You’re mounting the MCE directly to(through) the stock aluminum reflector with use of copper heat sinks. That’s a good idea because they are bent to fit under the hood. Thanks.

EDIT Dec 29: Anyone? Thank you.

EDIT Jan 18: Thank you anyways.

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My desklamp LED retrofit: Nichia 219 Desk Lamp Retrofit

I have since found a small pot with a power switch that fits in the space where the old power switch is. I still need to fab up a bushing so it can be secured in the hole. Gotta get those new stepper motors into the mill…

And while we are modding desk lamp thingies: Waldmann Omnivue Lighted Magnifier Nichia 219 Retrofit