# I'm not impressed with home LED lighting
**URL:** https://boards.straightdope.com/t/im-not-impressed-with-home-led-lighting/611224
**Category:** Miscellaneous and Personal Stuff I Must Share
**Created:** [January 30, 2012, 8:57pm UTC](https://boards.straightdope.com/t/im-not-impressed-with-home-led-lighting/611224 "2012-01-30T20:57:58Z")
**Posts on this page:** 20
**Page:** 2
### Author:  [@Mangetout](https://boards.straightdope.com/u/Mangetout)
#### Post date: [January 31, 2012, 10:16pm UTC](https://boards.straightdope.com/t/im-not-impressed-with-home-led-lighting/611224/21 "2012-01-31T22:16:01Z")
> [@TriPolar](#):
>
> Aren’t you in the UK? I know you aren’t an idiot, so forgive me for asking, but what voltage was that bulb made for?
It was labelled as the UK version, but I guess there’s no way to be absolutely sure, considering the source.
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### Author:  [@Mangetout](https://boards.straightdope.com/u/Mangetout)
#### Post date: [January 31, 2012, 10:19pm UTC](https://boards.straightdope.com/t/im-not-impressed-with-home-led-lighting/611224/22 "2012-01-31T22:19:38Z")
> [@Thoresh](#):
>
> Might I just add that if you know what you are doing you can easily replicate a “fluorescent hue”
> with LEDs.
Are you talking about creating tuned arrays of separate R G and B emitters?
> [@](#):
>
> Just because you picked an unsuitable LED color and did not hook them up properly does not mean that LEDs are not good for a living room setting.
I only picked the colour in the sense that it was a choice between ‘warm white’ or ‘blue-white’, and ‘hooking them up’ consisted of screwing the ready-assembled lamp into the socket.
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### Author:  [@Terr](https://boards.straightdope.com/u/Terr)
#### Post date: [January 31, 2012, 10:23pm UTC](https://boards.straightdope.com/t/im-not-impressed-with-home-led-lighting/611224/23 "2012-01-31T22:23:57Z")
I wish there was an LED bulb that was equivalent to 100W+ (preferably 200W). I have a light fixture that is 14 feet high that is burned out. If I am going to go through all the trouble of getting up there to replace the bulb, I want to replace it with a bulb that will last for 20 years or so. It doesn’t even have to be compact - the fixture has a cover that is big enough.
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### Author:  [@TriPolar](https://boards.straightdope.com/u/TriPolar)
#### Post date: [January 31, 2012, 10:25pm UTC](https://boards.straightdope.com/t/im-not-impressed-with-home-led-lighting/611224/24 "2012-01-31T22:25:24Z")
> [@Mangetout](#):
>
> It was labelled as the UK version, but I guess there’s no way to be absolutely sure, considering the source.
Well, you might as well take it apart now and tell us what you find.
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### Author:  [@What\_Exit](https://boards.straightdope.com/u/What_Exit)
#### Post date: [January 31, 2012, 10:26pm UTC](https://boards.straightdope.com/t/im-not-impressed-with-home-led-lighting/611224/25 "2012-01-31T22:26:45Z")
I’ve found the bulbs to be hit or miss so far. I have a great one from Home Depot of all places and then 3 sub-standard ones from Amazon (from China). I had another from Target I returned.
Meanwhile the LED flashlights and Xmas lights have all been awesome.
I think the lightbulb technology is still maturing and is not there yet.
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### Author:  [@Mangetout](https://boards.straightdope.com/u/Mangetout)
#### Post date: [January 31, 2012, 10:40pm UTC](https://boards.straightdope.com/t/im-not-impressed-with-home-led-lighting/611224/26 "2012-01-31T22:40:22Z")
I just disassembled one of them - it comprises:
Six long thin PCBs each carrying 16 (two rows of 8) LEDs
A circular end board carrying 12 LEDs
A small PCB with 9 discrete components - 4 small black diodes (obviously a bridge rectifier), an electrolytic capacitor, a metal film capacitor and three resistors.
The LEDs (all 108 of them) are wired in one big series loop.
The LEDs themselves are epoxy-encapsulated (although stubby) and conventionally soldered to the boards (I misremembered them as surface mount components, and once installed, didn’t get to see them again)
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### Author:  [@appleciders](https://boards.straightdope.com/u/appleciders)
#### Post date: [January 31, 2012, 10:40pm UTC](https://boards.straightdope.com/t/im-not-impressed-with-home-led-lighting/611224/27 "2012-01-31T22:40:38Z")
I love the ones I’ve got, but they’re just so dim that they’re really only suitable for bedside reading lamps or maybe around a bathroom vanity. They work really well in those situations, though. After another five years of R&D, I think that the drop in price and increase in output will make them pretty much ubiquitous.
Incidentally, I’m noticing a change in behavior in myself and my friends in the last couple years-- whenever we’re moving out of a house we’re renting, taking all of our more-expensive CFLs and now LEDs is a big deal. Since the expense in those is more in buying them than operating them, it’s worthwhile to buy a couple cheap incandescents to leave behind to avoid being charged for it in the deposit.
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### Author:  [@Mangetout](https://boards.straightdope.com/u/Mangetout)
#### Post date: [January 31, 2012, 10:44pm UTC](https://boards.straightdope.com/t/im-not-impressed-with-home-led-lighting/611224/28 "2012-01-31T22:44:20Z")
The rectifier PCB is fairly simple - I’ll see if I can sketch a circuit diagram…
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### Author:  [@TriPolar](https://boards.straightdope.com/u/TriPolar)
#### Post date: [January 31, 2012, 10:44pm UTC](https://boards.straightdope.com/t/im-not-impressed-with-home-led-lighting/611224/29 "2012-01-31T22:44:40Z")
> [@Mangetout](#):
>
> I just disassembled one of them - it comprises:
>
> Six long thin PCBs each carrying 16 (two rows of 8) LEDs
> A circular end board carrying 12 LEDs
> A small PCB with 9 discrete components - 4 small black diodes (obviously a bridge rectifier), an electrolytic capacitor, a metal film capacitor and three resistors.
>
> The LEDs (all 108 of them) are wired in one big series loop.
>
> The LEDs themselves are epoxy-encapsulated (although stubby) and conventionally soldered to the boards (I misremembered them as surface mount components, and once installed, didn’t get to see them again)
Sounds like my flashlight. Except that’s running off a rechargeable at much lower voltage. Unless there’s more to yours, it sounds like they were driving the LEDs at line voltage. Or at least the first one.
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### Author:  [@Mangetout](https://boards.straightdope.com/u/Mangetout)
#### Post date: [January 31, 2012, 10:53pm UTC](https://boards.straightdope.com/t/im-not-impressed-with-home-led-lighting/611224/30 "2012-01-31T22:53:37Z")
I tell a lie - the 108 LEDs are wired in two strings of 54 (the connection wires between the PCBs are a bit of a tangle)
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### Author:  [@astro](https://boards.straightdope.com/u/astro)
#### Post date: [January 31, 2012, 11:32pm UTC](https://boards.straightdope.com/t/im-not-impressed-with-home-led-lighting/611224/31 "2012-01-31T23:32:55Z")
I have single “[Cree](http://www.cree.com/)” LED bulb in my 2 year old flashlight, it really puts out the light and it’s as powerful as the day I got it, and I have used the hell out of this flashlight. The flashlight cost $ 50 new.
Click on the Cree link above for info on state of the art LED lighting tech.
I think it’s less an issue of LED tech being bad, and more an issue of “affordable” LED tech for house lighting not being quite ready for prime time. One Cree LED can cost more than dozens of cheaper units.
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### Author:  [@Mangetout](https://boards.straightdope.com/u/Mangetout)
#### Post date: [January 31, 2012, 11:57pm UTC](https://boards.straightdope.com/t/im-not-impressed-with-home-led-lighting/611224/32 "2012-01-31T23:57:54Z")
OK, the circuit board is a bridge rectifier with:
a 4.7μF electrolytic capacitor (in parallel with a 1 MΩ resistor) across the outputs - presumably this is the bit that does the waveform smoothing
a metal film capacitor (again, paired with a 1 MΩ resistor) on one of the 240VAC input lines - isolation?
A fat 120Ω resistor on one of the output lines, which then splits to drive a parallel pair of 54-LED chains
---
### Author:  [@jz78817](https://boards.straightdope.com/u/jz78817)
#### Post date: [February 1, 2012, 12:01am UTC](https://boards.straightdope.com/t/im-not-impressed-with-home-led-lighting/611224/33 "2012-02-01T00:01:59Z")
can you link to them (or something similar) in eBay? just out of curiosity…
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### Author:  [@Mangetout](https://boards.straightdope.com/u/Mangetout)
#### Post date: [February 1, 2012, 12:22am UTC](https://boards.straightdope.com/t/im-not-impressed-with-home-led-lighting/611224/34 "2012-02-01T00:22:58Z")
It’s any of [these](http://www.google.co.uk/search?q=108+led+corn+lamp+warm+white&hl=en&client=firefox-a&hs=4ij&rls=org.mozilla:en-GB:official&prmd=imvns&source=lnms&tbm=isch&ei=voUoT7ypHqjQ0QW4i_HeBA&sa=X&oi=mode_link&ct=mode&cd=2&ved=0CGAQ_AUoAQ&biw=1024&bih=468) fellas.
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### Author:  [@Mdcastle](https://boards.straightdope.com/u/Mdcastle)
#### Post date: [February 1, 2012, 12:28am UTC](https://boards.straightdope.com/t/im-not-impressed-with-home-led-lighting/611224/35 "2012-02-01T00:28:06Z")
Any ideas when they’ll come out with an LED replacement for a 1000 watt high pressure sodium lamp?
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### Author:  [@jz78817](https://boards.straightdope.com/u/jz78817)
#### Post date: [February 1, 2012, 12:38am UTC](https://boards.straightdope.com/t/im-not-impressed-with-home-led-lighting/611224/36 "2012-02-01T00:38:39Z")
> [@Mangetout](#):
>
> It’s any of [these](http://www.google.co.uk/search?q=108+led+corn+lamp+warm+white&hl=en&client=firefox-a&hs=4ij&rls=org.mozilla:en-GB:official&prmd=imvns&source=lnms&tbm=isch&ei=voUoT7ypHqjQ0QW4i_HeBA&sa=X&oi=mode_link&ct=mode&cd=2&ved=0CGAQ_AUoAQ&biw=1024&bih=468) fellas.
ah. one of the images linked me to an eBay auction. the description says “110-220 volts.” by your teardown description, it doesn’t sound like there’s a switch-mode power supply in there. I don’t see how it can tolerate that range of mains voltages without one.
> [@Mdcastle](#):
>
> Any ideas when they’ll come out with an LED replacement for a 1000 watt high pressure sodium lamp?
well, there are plenty of LED panel streetlights going up in my area. I don’t know the wattage equivalency, and they aren’t omnidirectional.
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### Author:  [@Mangetout](https://boards.straightdope.com/u/Mangetout)
#### Post date: [February 1, 2012, 12:55am UTC](https://boards.straightdope.com/t/im-not-impressed-with-home-led-lighting/611224/37 "2012-02-01T00:55:18Z")
> [@jz78817](#):
>
> ah. one of the images linked me to an eBay auction. the description says “110-220 volts.” by your teardown description, it doesn’t sound like there’s a switch-mode power supply in there. I don’t see how it can tolerate that range of mains voltages without one.
The ones I looked at before buying were all either 110 or 240 volts - I’d expected they would have the LED boards wired up differently and/or a different step down resistor - otherwise I wouldn’t have thought they would tolerate the range at all (either catching fire on the higher voltage if designed for lower, or failing to light at all on the lower one if designed for higher)
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### Author:  [@The\_Second\_Stone](https://boards.straightdope.com/u/The_Second_Stone)
#### Post date: [February 1, 2012, 1:03am UTC](https://boards.straightdope.com/t/im-not-impressed-with-home-led-lighting/611224/38 "2012-02-01T01:03:21Z")
I’ve picked up a number of Sylvania led bulbs at Lowe’s with a 2700k color. I’ve been very pleased with them, except they flicker when dimmed. What does displease me is that they are still far too expensive to use throughout the house.
Personally, I find the light pleasing, but I haven’t talked to interior designers about them yet.
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### Author:  [@Michael63129](https://boards.straightdope.com/u/Michael63129)
#### Post date: [February 1, 2012, 1:57am UTC](https://boards.straightdope.com/t/im-not-impressed-with-home-led-lighting/611224/39 "2012-02-01T01:57:52Z")
> [@Mangetout](#):
>
> OK, the circuit board is a bridge rectifier with:
> a 4.7μF electrolytic capacitor (in parallel with a 1 MΩ resistor) across the outputs - presumably this is the bit that does the waveform smoothing
> a metal film capacitor (again, paired with a 1 MΩ resistor) on one of the 240VAC input lines - isolation?
> A fat 120Ω resistor on one of the output lines, which then splits to drive a parallel pair of 54-LED chains
That is pretty much what I thought, except for the bridge rectifier. One thing to note about that arrangement is that current is highly dependent on the input voltage and the voltage drop across the LEDs (they should have at least used two resistors, one for each string). In fact, a 1 volt change across a 120 ohm resistor will increase/decrease current by 8.3 mA, or 2 watts at 240 v.
Actually, I am surprised that it worked at all with 240 v (340 peak) across the LEDs with just a 120 ohm resistor; assuming a voltage drop of 3.5 volts per LED, 54 LEDs would drop 189 volts, leaving up to 151 volts across the 120 ohm resistor - that is over 1.25 amps of peak current (625 mA per string IF they were exactly the same) going through LEDs probably rated at 20 mA at the most (LEDs drop more voltage at higher currents, but even 5 v per LED gives 70 volts across the resistor).
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### Author:  [@Michael63129](https://boards.straightdope.com/u/Michael63129)
#### Post date: [February 1, 2012, 2:06am UTC](https://boards.straightdope.com/t/im-not-impressed-with-home-led-lighting/611224/40 "2012-02-01T02:06:42Z")
Forgot to mention - if the metal film capacitor is in series with one of the input lines, then current would be lower than stated in my previous post, dependent on its value (capacitive reactance). Still not a really good design though.
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