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Old 01-08-2015, 09:17 PM   #21
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The LEDs I fried had what looked like a small resistor on one leg and a lead on the other. I can't be sure because it looks like the resistor is what burned. The whole thing is put together like a tiny circuit card with 42 LEDs on it.
OK. The resistor is a cheap way to limit the current by wiring in series with the LED array. The voltage drop across each LED varies with the type, but is usually 2.5V to 3.3V. The 42 LEDs are wired as parallel strings, with each string consisting of 3 or 4 LEDs in series, such that the voltage they need is something less than 12V. Then, the single resistor is wired in series with the entire array, and it absorbs the difference between 12V and whatever the LED strings need. Or perhaps each LED string has its own resistor, but the concept is the same.

In order for the resistor to be more effective in limiting the current over a wider voltage range, meaning reducing the current swing in the presence of voltage variations, it will need to have a relatively large voltage drop across it relative to the voltage across the LED array. This means more power loss, less lighting efficiency, and in this case the resistor was undersized and got burned out.

The proper way to regulate current is with a miniature DC/DC converter circuit, but this is easier to mount inside the base of a regular household bulb than in a 12V automobile lamp. I have seen 12V auto LEDs for sale at a high price of $15-20. I wonder if these have a real regulator.

PS. I built my own circuit, and not using microminiature components ended up with a regulator of about 2 cu.in. in volume. It was still small enough to be hidden inside the RV light fixtures. Each of these circuits can run two 10-Watt LED modules, each equivalent to a 60W incandescent. I have shown photos of my homebrew RV lights in another thread. See: Incandescent, CFL, LED, Halogen.
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Old 01-08-2015, 09:32 PM   #22
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I would bet that more than half get thrown in the garbage. I know when I had Section 8 renters, they did not recycle anything. All of it went in the trash.

Hmm, I live in a rural small town, and based on my experiences I would take the "over" bet with 75%. I have to confess, though college educated and never "sectioned 8" I haven't recycled bulbs. Never gave it a thought shamefully. I know home pollutant materials have changed, but I sure miss the days growing up when every little town had a city dump. Now they have a one time a year event, and snuck it by me this year without their usual public announcement. Now I am stuck with a pile of crap for another year.


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Old 01-08-2015, 09:41 PM   #23
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Hmm, I live in a rural small town, and based on my experiences I would take the "over" bet with 75%. I have to confess, though college educated and never "sectioned 8" I haven't recycled bulbs. Never gave it a thought shamefully. I know home pollutant materials have changed, but I sure miss the days growing up when every little town had a city dump. Now they have a one time a year event, and snuck it by me this year without their usual public announcement. Now I am stuck with a pile of crap for another year.


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My theory is that by throwing sway some recyclable material in the landfill, we give the people of the future something to find when they dig up the landfill looking for valuable items. Some of that is already happening with the rare earths in cell phones that may be in landfills.

Another place people of the future can find valuable minerals is in wilderness areas in the USA. I'm all for locking those minerals up like they are until we really really need them.
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Old 01-08-2015, 10:23 PM   #24
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Switching to LED fast in our household.
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Old 01-08-2015, 10:23 PM   #25
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LED bulbs do not last 20 years. Well, at least the electronics are not going to last 20 years. See, they use a switcher power supply and have electrolytic capacitors that are good for about 2000 to 5000 hours depending on temperature. The higher the temperature, the quicker they fail.

That being said, the LED elements themselves are quite robust and likely to last 20,000 hours or more.

I had 6 out of 30 bulbs fail within a 2 year period so I scavenged the little round circuit board with the cluster of half watt LED chips (about 18 chips total for 9 watts of LEDS). I found they run on about 40 volts DC and using a 12V to 40V DC-DC module I made 18 watt LED outdoor fixtures for our RV camper out of them. I put in a current control so I can adjust the draw and output...they blind you at about 3 watts and light up the forest for a football field at full output.


Edit: I missed NW's post. Evidently we have a lot of EE's on here!
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Old 01-09-2015, 12:10 AM   #26
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I switched my house over to LEDs this summer over the course of several paychecks. Really enjoy them, but some words of caution since they're relatively expensive: research color warmth (the "daylight" white is almost xray material) and models that have an audible hummmmm... DW made me get rid of 4 in the master bath because she could faintly hear them. Buy in small batches until you have confidence in the strength, color and noise. Ive had good luck with Phillips, but they are more expensive than Cree.
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Old 01-09-2015, 06:13 AM   #27
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I like the Cree LED bulbs, hate those CFLs.
Me too.
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Old 01-09-2015, 07:27 AM   #28
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I have never bought these horrible things, their light gives me headaches and I don't care to introduce Mercury vapor into my home. I filled a pantry shelf with "illegal" bulbs a couple years ago and waited for LED lights to drop in price.
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Old 01-09-2015, 07:29 AM   #29
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I ordered 10 LED car light bulbs from Amazon for 20 bucks. Installed two last night to see how they looked in my RV. After about 3 minutes, one blew the LEDs off the socket and the other was literally smoking. These were supposed to be 12 volt bulbs. They looked OK while they worked, but 3 minutes was a pretty short life span!
Insanity: doing the same thing over and over again and expecting different results. - Albert Einstein

I got an answer back through Amazon from the distributor: "hi,it depend on 12v,can we make a full refund. is it ok?thank you."

At the risk of being called insane, I think I will try a couple more of these before I send them back.
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Old 01-09-2015, 08:10 AM   #30
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I have never bought these horrible things, their light gives me headaches and I don't care to introduce Mercury vapor into my home. I filled a pantry shelf with "illegal" bulbs a couple years ago and waited for LED lights to drop in price.
Yep, I'm pretty happy with my decision to stock up on 40 and 60 watt incandescents. I have had horrible results with the few CFLs I experimented with. And I tried a couple early LEDs and didn't like the light quality.

I don't mind paying the extra few dollars/month to have light that I'm happy with, especially since so many of ours are on dimmers. By the time I'm running low I'm hoping that they'll have all the cost inefficiencies and bugs worked out of the LEDs.
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Old 01-09-2015, 08:27 AM   #31
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We've converted most of the lighting in our home to LED over the past 2 yrs and are completely satisfied. The price continues to fall and I have noticed an impact to our electric bill each month. Some of the lights we just leave on all of the time since the electrical consumption is so small.

I did try the CFL route but the color was hit or miss. They did fail periodically but not as frequently as Edison bulbs.

If you're sticking to incandescents you might try either severe service or 130v bulbs. Severe service are more expensive, but I have found 130v bulbs from easterm Europe packaged in some of the bargain store brands. They both seemed to have longer life. But, the energy (and associated $$) savings isn't there, except for the replacement costs.

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Old 01-09-2015, 08:37 AM   #32
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I have to second the idea that LED bulbs do last a long time, but the CFL ones I installed have to be replaced a lot more often than what I was led to believe.
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Old 01-09-2015, 08:45 AM   #33
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I tried the CFLs and they blew out much more quickly than I expected. Also the light color was an icky yellow/green, and they took a long time to get to full brightness, especially when cold.

LEDs are so much better.
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Old 01-09-2015, 09:03 AM   #34
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I've had pretty good luck with CFLs, got some that are in use for over 7 years. Except with the BR30's floods in recessed fixtures. Lucky to get 18 months out of these. As the kitchen lighting is mostly recessed, went back to 75w halogens. We have a side counter where the recessed lights are on typically 10 hours a day. As soon as I use up my supply of BR30 CFLs, It'll be the first place converted to LEDs, hopefully as LED pricing drops.
The curly ones have a good life, the spots/flood not worthwhile.
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Old 01-09-2015, 12:19 PM   #35
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I find that either they blow out within a year or they last "forever."

I got one of these and it's quite nice. I'm going to get some more--it will be nice to have dimming available again.

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Old 01-09-2015, 12:39 PM   #36
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Have had three CFLs fail in seven years, all flood lights in a bathroom, where they get cycled more often, and are subjected to more temperature and humidity changes.
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Old 01-09-2015, 08:48 PM   #37
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You remember when you had to buy CFLs at a premium price compared to the resistance bulbs that worked predictably? You remember how the CFLs were to outlast the old style bulbs by months and months? You remember how they didn't? Well, CFLs are passe and icky - nobody with any couth uses them anymore. You need to pay a bunch extra for LEDs - they'll last for twenty years or more! Really! ....
Yup. This time it's different....
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Old 01-09-2015, 09:05 PM   #38
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I find that either they blow out within a year or they last "forever."

I got one of these and it's quite nice. I'm going to get some more--it will be nice to have dimming available again.
Al, do those dim properly with a normal (old fashioned) dimmer? I know some LEDs are supposedly dimmable, but require a new dimmer to work properly. Also, I was reading through the specs and noticed you can't use them in an enclosed fixture, like a ceiling globe. Too bad for that.

I noticed a couple of the reviews said the bulbs aren't really the same size as a standard A19, being a little bit wider. That might impact their use a bit too. I ran into a similar problem with the CFLs I tried. They were a little longer than the incandescents they replaced, and didn't fit one of my fixtures properly.
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Old 01-09-2015, 09:45 PM   #39
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Temperature, humidity, orientation. CFLs are very sensitive to all, more so than incandescents.

My theory is that when they rate the CFLs, they test them like this:
- low humidity
- orientation with base at the bottom (so heat rises up)
- moderate temperature
- airflow over the device

It is all a cheat. If you have a CFL with the base at the top (bulb pointing down) in a fixture, outside, the thing will not last long at all.
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Old 01-09-2015, 09:56 PM   #40
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Recently, I bought the Philips flat LED that T-Al shows in the earlier post. It was at home when I read the instruction that the bulb could not be used in an enclosure, so I returned it. As JoeWras said, the toughest part of designing an LED bulb is arranging for heat dissipation. The 100W-equivalent bulb costs a lot more the 60W one for that reason, I believe.
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