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Custom LED bulb advice needed


Steven

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This question is not about Christmas lights, but I feel this is the best time and place to ask because this forum is filled with LED lighting experts.

Our kitchen has a vaulted ceiling that is about 15 feet tall. Because it seemed like a good idea at the time we moved in, the 1970's "hanging egg" light fixtures were replaced with recessed lighting fixtures. Due to the limited space between the ceiling and the roof, we were forced to use recessed fixtures that are shorter than others, which require "150 Watt Par38 Side Prong" light bulbs, like these:
[align=center]par38_sprong.jpg[/align][align=left]The trouble is that when one of these burns out, I have to haul my 12-foot ladder into the kitchen, after cleaning it with a rag (because it's the same ladder I use for the Christmas lights). It's quite a production, so it usually has to wait until the weekend to replace a bulb.[/align][align=left]To save myself this trouble, I would like to replace these with LED bulbs, but they just can't be found in this size. However, after seeing the Rainbow Floods, I'm now thinking that I could build a bulb myself.[/align][align=left]The first issue is the enclosure. It may be tricky, but I'm thinking of taking a burned-out bulb and using a glass cutter to cut the end off. I can then stuff it with LEDs and resistors and close the end with hot glue or epoxy.[/align][align=left]Second issue is what kind of LED bulbs and where to buy them. I don't want to use all white, because that's too harsh a look for the kitchen. I'm thinking about mixing white bulbs with some yellow and/or red and green to get more of a yellow incandescent look.[/align][align=left]So any ideas from you LED experts?
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Id use a par 30 or 38 LED Flood, (120v ac) and cut it down to fit your side prong fixture. Its going to be a lot easier to trim the back off the ready-made par30/38 - even if you just cut it and run jumper wires to the socket, then it would to buy individual LED's and assembel them with resistor networks

The 30 will fit a bit easier, but the 38 will have more might.

http://www.eaglelight.com/product/XP30-E27-5W20S/PAR30-LED-flood-light-with-20-SMT-LEDs-5W-110V-screw-in-light-bulb.html

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gizmomkr wrote:

Id use a par 30 or 38 LED Flood, (120v ac) and cut it down to fit your side prong fixture. Its going to be a lot easier to trim the back off the ready-made par30/38 - even if you just cut it and run jumper wires to the socket, then it would to buy individual LED's and assembel them with resistor networks

The 30 will fit a bit easier, but the 38 will have more might.

http://www.eaglelight.com/product/XP30-E27-5W20S/PAR30-LED-flood-light-with-20-SMT-LEDs-5W-110V-screw-in-light-bulb.html

Most household LED lighting is for accent lighting only, mainly, glorified nightlights. Notice the above link, replaces a 50watt aquivelent bulb and costs $55 bucks to boot. If you are using these bulbs to really light up the kitchen, don't bother with LED technology at this time. The more high powered led's lack warm white characteristics and may have heat issues. You will be happier if you can find CFL par38 bulbs with the side mount plug. If you still persue building your own, shop on Ebay, there are a lot of varieties of led's and brightnesses.
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Maybe this is more to what Steven is looking for. Provided he is willing to do a little mod on the new bulb.

Never can say I have seen a bulb with side terminals like that Steven. Hope you find something that will provide a longer life so you dont have to fart with it to often.

In my offering I am not sure if this bulb is small enough in diameter, so be careful that it would fit if you become interested in it.

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I took a look at a close up pick of one those lamps. It looks to me that side base can be detached - worse case you break the lamp to salvage the base plug.

If you can get that off of the light you can but a screw in base par38 LED from someone like 1000bulbs, superbrightleds, etc... Soider the base wiring to the screw in lamp, glue the base one and be done with thes $8, 2000 hour lamps...

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I stopped at Sams Club today to look at LED lighting for someone. While there I noticed they have a PAR38 LED bulb that puts out 570 lumens for about $20. They don't have it on their website to show you a link. It has the screw in mount, but it'a start. Also doesn't state daylight or warm white.
Just an FYI for anybody else looking at LED bulbs, Sam's Club has a decent variety of LED bulbs and continues to add new ones such as the one mentioned above. The bulbs with many little bulbs don't last a long time. I have some that are on 24/7, after about a year the bulbs begin to die off loosing effective output.

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I found another PAR38 LED bulb of interest. Menards here has an PAR38 bulb using a single high power led in it. Uses 15W and puts out 770 lumens and a $65 hole in your wallet. Doesn't specify color. Forgot to mention, it's dimable.

Steven, have you tried modifying any bulbs yet for the socket type you have?

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  • 1 month later...

I finished a custom-built LED bulb and installed it today. It doesn't have the same output as the bulb it replaced, but it's good enough for one corner where we just have brooms and vacuums.

To build it, I started with a burned-out bulb:
IMG_2260.JPG

I (carefully?) removed the back, then coated the sharp, jagged edge with Plasti-Dip:
IMG_2259.JPG

I ordered a bunch of LEDs from Phenoptix, including 50 Ultra Bright White 5mm and 10 Ultra Bright Yellow 10mm. I wired these, and some more that I had laying around together, using an old Hollerith card I had.
IMG_2261.JPG
IMG_2262.JPG

Here's what it looks like after being stuffed in the bulb:
IMG_2265.JPG
IMG_2266.JPG

The lamp has 74 LEDs, including 50 Ultra Bright White, 10 Ultra Bright Yellow, 2 Ultra Bright Green, and 12 other white LEDs I had laying around. It has a single 1A rectifier, and two sets of resistors that each come out to about 750Ω. I determined the number of LEDs and value of resistors by trial and error, until I came out with 25mA on each set. 25mA * 2 * 120V gives 6 Watts. That's not much compared to the 150W bulb it replaced.

Unfortunately, it's not as bright as the 150W bulb, so we won't be replacing the rest at this time, but I'm thinking that in a few years, the technology may catch up. I'm just hoping it will fit in a PAR38 Side Prong bulb.

By the way, if you want to see any of these pictures in higher resolution, click on them.

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And there are those who said the days of the Hollerith card had passed...;)

Seriously, I'd be real nervous, actually, beyond nervous, about using that as a mounting material..heat, solder, weight...all makes it prone to crumbling, and then shorts..

Even if you were dropping supply voltage down to the 12V range before you make any connections to the paper mounting material, I wouldn't do it. Reliability suffers with any supply voltage, the risk and potential fire hazard skyrockets if you are making a 110VAC connection to that paper "circuit board".

Instead, you could go with a piece of perf board, which is a material really designed for what you are tryigng to do: (http://www.radioshack.com/product/index.jsp?productId=2103804&CAWELAID=107598474)

You can get various sizes and hole spacings via mail order also.

The cost is minimal for the level of risk you take on using paper as a mounting material...

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