Instructables
Picture of LED Appliance Bulb Replacement

If your microwave or other appliance has a built in light, chances are you have been wondering how to replace the anemic, inefficient bulb in it with a high power LED.  Your time is at hand, as in this Instructable I will show you how to replace a 40W incandescent appliance bulb with a 3W white LED that will generate as much or more light at a >10X reduction in power consumption.  Total project cost around $10.   Fun, easy, cheap.
 
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Step 1: Assemble your components

Picture of Assemble your components

This project will require a handful of parts, pictured below. Your project may vary slightly depending on the bulb you are replacing, but the basic idea will be the same. The main components are the LED and the driver.

The driver is a cheap 120VAC to constant current unit built and sold direct from China. This is not a particularly safe, elegant, or reliable driver but the price is hard to beat. When working with electricity, especially 120VAC, be careful and do not take any chances.

The LED is a Cree XRE high efficiency warm white source, rated at 74 Lumens at 350mA.

List of Parts
Cree XRE Warm White LED http://ledsupply.com/creexre-ww.php
(You should get the XPG now, since it is more efficient and cheaper http://www.ledsupply.com/creexpg-ww105.php )
3W 120VAC LED Driver http://www.dx.com/s/13552

Bulb to be replaced
Scrap of thin wood (plywood or popsicle stick)
Small section of aluminum channel for heatsink
Misc Wire
Misc epoxy (i.e. JB Weld)

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carverno128 days ago

I can't find the 3W 120 VAC LED Driver.

jmengel (author)  carverno121 days ago

The DX website has changed a bit, here is the new link. I'll update the link in the text as well.

aandroyd6 months ago

would scrap aluminum (like a soda can) work for the heat sink?

loucoh7 months ago
I really want to make this but for the life of me can't separate the bulb from the base. Tried heat gun, gentle flame, boiling water, etc. Wasted about 10 bulbs! Any ideas?
jmengel (author)  loucoh7 months ago
Sometimes I've had trouble myself and have just crushed the glass out without destroying the metal based as best I could. It depends on the brand and age of the bulb I think. You'll need to clear enough glass out in the bottom of the base so you can solder a wire to the "nib" at the bottom center of the base. Also try not to cut yourself. :)
loucoh jmengel7 months ago
Thanks for replying. I've tried many times but cannot get enough room to solder. If you or anyone else who has done this successfully care to, I'd be glad to send all the parts for the two bulbs I need, and $25 for your trouble. I'll mark the base to show which side faces straight down.
jmengel (author)  loucoh7 months ago

I could possibly help you out. You should solder the wire from the outside. It sounds like you are trying to do so from the inside of the base. The whole "nib" is solder so what I do is apply the iron to the nib from the outside while pressing the wire in from the outside. When the solder melts, the wire comes through. If you need more help, send me a message directly.

jmengel (author)  jmengel7 months ago

Oops. I meant to say "apply the iron to the nib from the outside while pressing the wire in from the INSIDE."

loucoh9 months ago
Where can I find the aluminum stock for the heatsink??
jmengel (author)  loucoh9 months ago
You local hardware store or big-box retailer will have aluminum channel you can use.

http://www.homedepot.com/s/aluminum%2520channel?NCNI-5
loucoh jmengel9 months ago
Thanks very much.
hebejevee1 year ago
Beware of these " ready to go bulbs" (suggested by dalebesh)t he package size is described as Package size (L x W x H): 9 x 4 x 4 cm. My bulb measures 6.3 x 2.4 x 2.4 cm....no way they will fit in my vent hood light !
hebejevee1 year ago
Great instruct-able! I have struggled with these bulbs burning out in 3-4 months. The location makes them hard to change so they remain burned out for another month (frustrating my wife) I agree with the caution update that recommended against hot glue. Hot glue is my least favorite adhesive unless I'm glueing paper of cardboard ... I used jb weld for everything in this project (BTW JB weld is not conductive). I also screwed the led down to the heat sink (with JB weld underneath ). A small number 2 screw +nut worked well (though I did have to trim led pads away from nut with a razor knife). I also used some FR4 type perf board instead of the wood (it has a much safer heat/flammability rating compared to wood). The location of the bulb is very tight in my vent hood so be very careful to stay compact (I had to trim down the aluminum heat sink fins to make my first one fit)
dalebesh1 year ago
I am now using these bulbs.

http://www.gadgetsdealer.com/product447367.html

I got E12 to E14 adapters also. There are many sources of adapters including ebay.
The lamps don't give out a lot of light considering the number of leds on each module, but enough for my purposes. On the positive side, they run cool and screw right in.
I am planning some other uses for ones I built up..

I'll add a picture later of the finished 'lighted area'.
Just thought I'd mention that I've been running this bulb for over a year now over my microwave. It comes on automatically on a timer and is on for 12 hours daily. The timer switches it on on low setting and I never have any flicker. I built it as designed in the original plans posted. The bulb still works flawlessly. Thanks again for the posting the instructions.
dalebesh1 year ago
I should have mentioned also, the only ones available that will fit are rated at only 0.5-3 watts, you need at least 5W for an equivalent 25W output. They have them, but they are too big to fit the space available in over range microwaves.
jmengel (author)  dalebesh1 year ago
Do you have a link? I'd say it depends on the bulb. The design shown in this guide is directional while the typical incandescent or LED replacement is not. The reflectors in these under-range hoods are miserable, so a lot (~50%?) of the light directed away from the work surface into the reflector is lost. As my measurements show, using a single LED at around 2W (650mA at 3.1V) gives as much or more light than the 40W incandescent. Some of this is due to electrical efficiency and some of it due to configurational efficiency since the LED directs zero light away from the work surface.

Also, a lot of the commercial bulbs out there do not use the best LEDs. Using a state-of-the-art LED I'd expect another 25-50% more light output than I published.
dalebesh1 year ago
They do 'now'. They run around 8 bucks each, and up. So about twice the cost and less than half the fun. ;)
shane18001 year ago
Very cool you figured out how to do this. Does anyone sell something like this pre-made?
Davidwd1 year ago
You commented earlier on dimmers, but I didn't fully understand your reply.

My light on my microwave toggles from High-Medium-Low-Off. Will the medium or low settings damage the driver used in this project? Is there a different driver that would work better on my microwave's dimmer circuit?

My goal is to have less heat generated in the lamp enclosure, as I recently got a nasty burn when my hand brushed against the glass cover while reaching for a pot on the back of my stove.
jmengel (author)  Davidwd1 year ago
I'm not sure what dimming method is used by your microwave. Whichever method, the result is to reduce the effective average power to the incandescent bulb. The way the LED driver operates is to reduce the 120VAC to a lower level, rectify it to DC, and then the driver IC runs a set current through the LED by changing the output voltage. When the LED driver is presented with the varying power output by the microwave in med and low setting it may cause the LED driver to drop out and flicker because the DC voltage output by the rectifier will be below the output voltage required by the driver IC to maintain the set drive current. You'll have to try it out. There may be a better LED driver that can handle the med-low output of the microwave but I don't have a link for one. Dimmable LED drivers exist, they are less efficient (typically) and more expensive. I would say try the design as shown and see what the LED driver does.
smarks452 years ago
I'm a little concerned about driving 650-700mA into an LED rated for 350mA. That will definitely reduce the lifespan of the LED. A possible alternate current driver can be the 350mA constant current driver listed below. It also will drive 2 LEDs with no problem.
http://www.dealextreme.com/p/330ma-1w-power-constant-current-source-led-driver-85-265v-47060?item=26
jmengel (author)  smarks452 years ago
The Cree XRE maximum current is rated at 1000mA in cool white, 700mA in neutral/warm white.
Karlboer3 years ago
Bulb is complete. The dimmed setting makes no difference to this bulb (which is fine by me. My question below was just to make sure it wouldn't hurt the bulb). It cost me about $30 for supplies for two bulbs. I think it will easily save me $15/year in electric & cost of bulbs. Awesome! Thanks!

I gotta say that the light is a little..... harsh. Not quite as yellow (warm) as the incandescent). I was also surprised that the bulb takes a half second to turn on once the button is pressed. I wonder why.
010.JPG
A few days after posting this, by bulb burned out. The driver died. I had it hot glued to the back of the heat sink, and the heat sink melted the glue, causing a short circuit (I think that's what happened from my best guess). I still need to take the time to replace the driver and increase the size of the heat sink. Make sure your heat sink is big enough to dissipate the heat generated. I believe the LED came with a sheet that said the heat sink needs to be at least 3 inches (I assume that is total surface area, though it didn't say).

Let's try this again!
jmengel (author)  Karlboer3 years ago
Yes, I had a similar problem with hot glue although the bulb did not self destruct. I switched to an epoxy (JB Weld). If you dial back the current it will also help on the heat. The big issue for me was that the bulb sits inside a metal can on the bottom of my microwave, with a glass front, so that heat is pretty much trapped with no airflow. Add to that the fact that the bulb is usually on when I am using the stove, and heat is a problem. I expect that the LED life will be shortened from 50k hours, but since I don't use the bulb more than an hour a day I think it will last longer than the stove.

If it is just the driver, you should be able to drop in another one ($2). I usually order them in packs of 10 since they are cheaper that way and nice to have around if they burn out.

Thanks for sharing your experience. As convenient as hot glue is, it isn't for every project.
I ordered and installed the new driver on a larger heat sink. This time I wire tied (plastic) the driver to the board. Somehow I just couldn't bring myself to use epoxy to mount the driver. I finished the new light in May, and it has been going strong ever since.

Just to clarify, I am using it under the microwave in the same situation you did. There is no place for the heat to escape in that little glass and aluminum coffin.

Thanks again. It has been a fun project, and the results are fantastic!
jmengel (author)  Karlboer3 years ago
I edited the text to caution against hot glue in any location on the project. Sometimes it is so nice to be able to put a project together in minutes with hot glue, but like fat free Olestra potato chips there is no free lunch.
jmengel (author)  Karlboer3 years ago
The lower wattage incandescent bulbs are pretty yellow (2500K), even the "warm" white LEDs are only rated ~3000K and that is usually seems pretty generous.

LEDSupply.com is also now selling warm white Cree XP-G single LED star boards that are about 40% more efficient than the XR-E LED that I used. 105 Lumens at 350mA as compared to 74.

http://ledsupply.com/creexpg-ww105.php

I've noticed the start up lag as well. I attribute it to the time to charge the smoothing cap and the time needed for the current control loop to ramp up and stabilize.

Glad to see your successful bulb build. Let me know how it holds up. I've had no problems with mine, although it doesn't get used a whole lot.

-Jon
-max- jmengel3 years ago
start using the XM-L T6 LED!!! it is 100 lumens per watt, and 130 lumen per watt @ 700mA
jmengel (author)  -max-3 years ago
My reading of the datasheet puts the T6 bin at 140 lumens/watt at 700mA which is better than the XP-G R5 140/watt at 350mA and 115 lumens/watt at 700mA in cool white. I prefer a warmer white with a better CRI, at which point the XM-L and XP-G's are more similar in performance. Additionally, using more XP-G's and lower wattage is easier to heat sink and easier on the eyes. I'm currently building some 5 foot linear 15x arrays for a closet which will run each LED at 300mA for a distributed and easy on the eye >1000 lumens. Try looking at a single 1000 lumen XM-L at 3000mA? Painful.

The price for XM-L's is also still pretty high as they are "cutting edge", almost 2x the XP-G. Do you know of a good source for XM-L's at a decent low quantity price?

Thanks for the tips.

-Jon
What gauge wire did you use for this?
jmengel (author) 2 years ago
The driver modulates the output voltage to reach the programmed output current. The driver I specified for this build is a 1x3W driver pushing 650mA constant current designed to drive a single LED. The circuit consists of a step-down transformer a rectifier, and then a buck type constant current regulator. Using this circuit to run a 3-up style LED star is possible since the constant current driver doesn't care how many LEDs are in series as long as the supply voltage is higher than the forward voltage of the series LEDs (~10V for 3-up) plus some overhead (~1.5V) as well as the total power dissipated in the driver is less than rated maximum. Typical driver ICs can handle 9 LEDs in series before they max out. However, the other parts in the chain may not be rated for running 3 LEDs at 3W each. Particularly the transformer and rectifier may fail. In any case, the driver will run hot at 3x3W and wrapping in electrical tape may not be a good fix as the tape softens and unwraps when really hot. I've run 3x3W for short periods with these drivers but have not tried long term running in an enclosed space. If the door switch were to fail, I'd be worried about the driver failing after being on for a long time. The method of failure may or may not damage the fridge or cause an electrical fire. Caution is warranted. That said, the pictured heat sink is probably inadequate to run a 3-up for long runtime without degrading the LED lifetime (15,000 vs 50,000 hour lifetime). The two LEDs shown are probably running pretty damn hot if the light is on for more than a few minutes.
mvipond jmengel2 years ago
What is "pretty damn hot"?

I am currently connected to a thermo couple on the counter (room temp, not fridge) at 155 deg F. After 25 minutes.
jmengel (author)  mvipond2 years ago
Where is the thermocouple? The maximum junction temp is 150C (300F) for an XPG according to the datasheet. With a 6C/W junction to thermal pad resistance, and a 3C/W solder/star/paste to heat sink resistance, and a 6C/W heat sink resistance to the environment the temp at the junction could be already at 133C. (70C at thermocouple on heatsink + 6C/W * 6W (2 LEDs at 3W each) + 3C/W * 3W + 6C/W * 3W)

Running long term at a junction temp of 130C will reduce the LED lifetime. How much, I don't know. 30%? In a fridge application I would say the LED will still outlive the fridge unless the door switch fails and the LED starts running around the clock.

As a rule of thumb (ha!) I'd say you should be able to touch the LED heatsink indefinitely without burning yourself for a good thermal design for long runtime. In an intermittent application like a fridge, you are probably fine.

-Jon
mvipond jmengel2 years ago
Thermocouple was right between the two LEDs, on the heatsink, so, yeah, probably too hot for long term use, but that is at room temp ambient too.

I am gonna order some more supplies, and try again, with an improved heatsink design.

In the meantime, I feel comfortable using these in the fridge. Awesome instruct able! Thanks for all the good advice.
mvipond2 years ago
bump (I know this is a year old but...)

I just built two of these, I took some liberties with the design, and actually doubled the LEDs per "replacement bulb" Still trying to understand all the LED terminology, and was hoping to build a couple more "bulbs" with the cool white emitters. here:

http://www.ledsupply.com/creexpg-w139.php

and am concerned that the original drivers would be appropriate for this different LED.

These are for my refrigerator and freezer, each replaces a 60 watt incandescent cool white bulb.  I just couldn't stand having 120 watts of heater in my fridge, even if it's only on (in theory) when the door is open.

Input would be appreciated.  I was also curious if there was a different driver I could/should use to drive two LEDs, as in my current design, I just used two drivers.  The form factor of this was nice, but it's kind of "cheesy".

Thanks!
LED Appliance bulb1.jpg
jmengel (author)  mvipond2 years ago
The drivers will work fine, they provide a constant current which is what any LED prefers. The level of current desired may vary, but the XPG LED will happily run on these drivers. You can even use one driver and put the LEDs in series, wiring the + from the first of the LEDs to the - on the other and then having the + and - leads from the driver connect to the - on the first LED and the + on the second.

Having this in your fridge is a little bit concerning since you reach into the fridge with your bare hands and may contact the 120VAC wires. Make sure all the "hot" wires are covered and that the heat sink is isolated from 120VAC. Also be sure and use whatever bulb cover came with the fridge. I know some older fridges don't have a bulb cover, so if that is your case then I would be extremely careful. Additionally, the bulbs are certainly off when the door shuts. If not, all your food would spoil as your fridge ran flat out to try and keep cool. If you are worried about the theory of it, pull the shelves and the food out and climb inside and shut the door to find out. Good luck!

-Jon
mvipond jmengel2 years ago
Thank you for the quick reply! Regarding running the LEDs in series with one driver, how would that affect the light output?

Could a person use one of the "3 up" led stars with just one of these drivers?
http://www.ledsupply.com/creexpg-w354.php

The fridge is a bit of a mess actually. It's an LG french door model, one of the first ones (the new ones have LEDs from the factory) and there are well documented problems with the door switches failing, and the bulbs staying on. This results in the bulb housing actually melting, pictures have been seen on the internet of a stringy mess of melted plastic on top of food. LG has no real response except "changing the bulbs voids the warranty" SO that's the "why" for me with this project.

Details - I didn't like the "take the glass off of the lightbulb" although, if you had a non-standard lightbulb, that would be your best bet. Anyway, the base I used is actually one of those nifty things that you screw into a light socket, and make a "wall outlet" out of. SO, I just whittled out the plastic a bit, to expose the contacts, and soldered in the 110v leads. Then I filled that whole area with clear (non-electrically conductive) epoxy effictively insulating the 110v from the rest of the assembly. I ran the 110v leads up to my drivers, and then just wrapped the drivers with electrical tape. Further protection from the fridge user contacting 110V is afforded by the fact that there is in fact a clear plastic shroud over the "bulbs"

The installed look is awesome.

I don't understand completely the lumens that this is putting out, as the charts are a bit confusing (how many mA?) but I would say that these things are almost comparable to my O.E.M. 60 watt bulbs in this application.
fixrupr3 years ago
I just received the driver but it doesn't have the 4 white wires it has 2 white and 1 red and 1 black. I examined the circuit board and it has a positive for the red and black for the negative. The 2 white wires don't have anything on them. Should I connect those to the bulb and not the led?
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