Nichia 219 Desk Lamp Retrofit

When I was upgrading all the lighting in my house to LED lights (My adventures in LED home lighting) my favorite Ebay LED bulb seller often had some other LED type items on sale. I occasionally put in some lowball bids and wound up with some items for stupid cheap prices (anybody need any LED street lights?).

One of the items that I bid on and won was an LED desk light… 5 bucks or so and shipping costs were combined with some other stuff I bought that day. It was advertised as a 10 watt light, but was actually a 4.8 watt light. It used a Chinese 4x3 5000K LED array driven by an unregulated wall wart supply. The light quality was OK, but the CRI was probably around 70. It put out around 250 lumens.

Then Old Lumens got me hooked on those damn Nichia 219 4500K, 92CRI LEDs from Illumination Supply. So what’s a boy to do? Out with the old:

And in with the new (triple LED 20 mm star):

Add a tiny little driver:

And prestakazoo!:

I changed the wall wart to a 12V one. The driver puts out around 8 watts (9.5V, 0.8A). The fixture now puts out around 550 lumens. Without the reflector it only does around 350 lumens… this is the only light that I have that actually puts out more light with a reflector (due to the black head of the lamp soaking up light like a sponge). I left out the old lens. The LEDs were pretty close to the edge of the lens, plus with it open it gets better airflow. The head runs around 55C.

The driver that I used can do 1.2 amps. I could mod the sense resistor and get more light. The driver also supports dimming via PWM, a variable voltage, or a variable resistor (aka a pot). I am going to replace the power switch with a pot, but need to fab a bushing. The hole for the switch is too big for the shaft of the pot and it can’t be secured in the existing hole.

Nice aren't they? I really want to do some home lights with those, someday...

I hope we see some more high CRI leds come out soon, in that neutral to warm range.

I just ordered more Nichia leds to do some 1AA, 1AAA & Solitaire mags.

Maybe I should start doing desk lamps?

I have a pile of them to do my workshop lighted magnifier. I am going to use either 6 or 9 of them. It currently uses small fluorescent tubes.

I also just installed a couple of those 3x20mm Nichia stars and that same driver into a couple of Chinese wall-wash fixtures. I have them wired with Deans connsctors for use with either a car lighter plug or LiPo packs. I also added some stong-ish magnets to the mounting bracket and put hand knobs on the bracket bolts. I keep one in each car.

If you want REALLY nice high-CRI bulbs, try the Sylvania Ultra-LED bulbs. 95 CRI. I have a couple dozen of the 10 watt, 550 lumen PAR20 bulbs in my kitchen and office. They put out considerably more light than 50 watt halogens.

Bridgelux has a Decora line of LED arrays with a 98 CRI… not sure if they are available yet.

nice! I’ve been meaning to make a couple of adjustable LED work lights for my lathe for some time, but I was going to use some spare old CW P4s. Now I’m wondering if I should just stump up the cash and get a couple of Nichia 219s instead.

I’m also about to replace the front dome light in my car with WW XR-Es (from some old 12V bulbs) as the festoon bulb in there has blown again. I did the rear dome light with the same and it’s awesome - similar tint to the originals, but way brighter and cooler.

Still thinking about some high CRI lights for the bathroom mirror too…

Nice job, Tex! I really like that light. You have a link for that driver you used to share with your buddies on BLF? ;)

Nice work texaspyro, once again innovative Texans at work!!! :bigsmile: :stuck_out_tongue:

I bought the drivers from LighTake. They were around $15 for 5 of them… unfortunately they no longer seem to sell them. They are really nice little drivers, based on the PT4115E driver chip. They can take up to 30V AC/DC input.

The cheapest place that I have seen with them is now 5 bucks a pop: http://www.ebay.com/itm/1pc-10w-LED-Driver-Led-Constant-Currant-Power-Supply-For-1-10w-led-DC12v-/180917274371?pt=LH_DefaultDomain_0&hash=item2a1f828703 Some places want $9 ea!

You can get the bare chip for less than 50 cents… There are lots of MR-16 type 10W drivers available for under a couple of bucks each, but I don’t know if they have the dimming feature.

Definitely go with the high-CRI lights. They are perfect for such critical inspection applications.

I did a little snooping around on Ebay and found these:

http://www.ebay.com/itm/10pcs-Power-Driver-for-1x10w-LED-Light-Lamp-12V-MR16-/110920170823?pt=LH_DefaultDomain_0&hash=item19d35b7d47

They use the PT4115 driver chip (in a different package). Should work well. The price is right.

Also found these. They look just like the diver that I am using, but don’t show the back of the board to be sure. http://www.ebay.com/itm/10W-LED-Driver-DC12-24V-AC-DC-12v-For-10-Watt-LED-Light-/220772630797?pt=LH_DefaultDomain_0&hash=item336713010d

I wonder.. why not just use a 230V buck driver right away?

The lamp was designed for wall wart low voltage DC power. Running line voltage into it is not a good idea. Also line voltage drivers are much bigger than the MR16 style driver and would be harder to fit into the base.

Here is an image of the Gretag-Macbeth color checker chart lit by the Nichia desk lamp:

And the Chinese wall-wash lights. These cost around $25 for two of them. They were sold as 10 watt, 700 lumen. They were actually 5 watt, 250 lumen. The drivers in them were rather nice 600 mA drivers potted in silcone in an aluminum extrusion.

I swapped the drivers for those same drivers that I used in the lamp and that boosted the output to around 400 lumens (but at 14.5V in, the LEDs in the array had a large Vf). I replaced the Chinese arrays with a 3xNichia 219 stars. I can’t really measure the output since the reflector is bigger than the port in my sphere, but it is over 400 lumens. I also added magnets and knobs to the mounting bracket (not shown). I had to enlarge the hole in the reflector with a Dremel tool to make it fit the Nichia stars.

Nice work texaspyro. I reckon if I started buying and modifying desk lights with LEDs, it would be the straw that broke the camels back and she would have me locked up in a padded cell. Keep it up.

Very nice mod texaspyro. I have that same desk light in use on my desk. It puts out good light but would be much nicer with triple nichia 219’s. I would definitely like the dimming feature. If I were to get that same driver your using, where would I solder on the wires for a pot?
I also have the nichia bug. Im currently planning to mod my old ufh3 headlight with a nichia running as a mule.

thanks, I’m sold! What about optic/ reflector vs. mule/ bare LEDs? It would be a spot application, but also at a very short distance.

Thanks for the links. :wink:

On the lamp that I did, I used the reflector. The head is dark black and absorbed a lot of light. I suspect a bare LED would work just fine.

The chip has a DIM pin. Connect the pot between DIM and Ground (Pin 8 and Pin 5/6/7 on the SO-8 package on that driver). A 250K pot uses about half the range of the pot. I suspect that a 100K pot with a 20K-30K series resistor would work better. Too small of a total resistance and you can’t get full brightness. Too large of an added series resistance and you can’t dim it to full OFF.

I haven’t tested one yet, but an audio taper pot may give a better dimming profile. The human eye does not perceive brightness linearly, so an audio taper (logarithmic taper) pot might look better.