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There's something off about LED bulbs

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Re: There's something off about LED bulbs

#901

Post by Dylan16807 »

thrashh wrote: post #865
tshaddox wrote: post #838

Earlier quoted context omitted.

I mean there’s gotta be some reasonable price limit where you stop blaming the consumer. If each supposedly higher-quality LED bulb is $50,000 are you still blaming the consumer? Especially when the consumer has can’t realistically even know if they’re going to get a higher quality bulb or just a $5 bulb resold for $50,000.

It’s only a few $ more. And it says on the box. I usually stick to the same brand too. All Phillips bulbs are 90+ CRI and some are 95+ so I just buy Phillips. Problem solved.

"A few dollars" is a bad way to describe the difference between $2 and $25.

Re: There's something off about LED bulbs

#902

Post by xnx »

jandrese wrote: post #804
JohnFen wrote: post #198

Earlier quoted context omitted.

Almost all LED bulb failures are because the power supply died due to overheating, not the LEDs themselves. I harvest the LEDs out of dead bulbs to use in hobby projects. With Edison-style bulbs, anyway, the orientation they're mounted in makes a huge amount of difference. They're last a lot longer if they're oriented upright (base down) than in any other orientation because it reduces the heat buildup in the power s…

Sometimes it is the power supply, but I've also had a number that died simply because one LED burned out and failed open. Because they are wired in series it only takes one failed LED to take out the entire bulb. If you're a cheapskate you can sometimes get a bulb working again by testing the circuit and bypassing the burned out LED with a jumper wire. If the bulb dies but you notice that all of the elements are stil…

Just saw a TikTok that showed routing around a failed LED by connecting the traces with a line from a graphite pencil.

Re: There's something off about LED bulbs

#903

Post by Dylan16807 »

novok wrote: post #889
formerly_proven wrote: post #24

There's a lot wrong with LEDs in general and retrofit (E27 bulbs) in particular. In no particular order - LED emitters driven hard for cost reasons, age and fail quickly - Power supplies driven hard for cost reasons, age and fail quickly - Poor CRI and SSRI - Flickering - Dim-to-warm is uncommon - Poorly designed power supplies that age and fail quickly - The same light quality is vastly more expensive to achieve wit…

A bunch of this is driven by power efficiency requirements, creating a flickering low quality mess. Like no-flicker LED lights usually have a worse power factor.

A bulb gets a burst of power every 120Hz, so it would only use about .075 joules per cycle. Half the time is spent above 110v, and half is under 110v, so we need to store less than 1/240th of a second of power to have a perfect output and a perfect power factor.

Let's put a capacitor before the regulator to store that power, and design the regulator to compensate for how the voltage will vary over each cycle. Since we don't want to drain our capacitor entirely, let's spec it for .05 joules at 100v, which means 10µF.

Digikey says a 10µF 200v capacitor costs ten cents.

If there's flicker, I blame the voltage regulator or lack thereof, not the requirement of power efficiency.

Re: There's something off about LED bulbs

#904

Post by midoridensha »

xpe wrote: post #864
midoridensha wrote: post #857

Earlier quoted context omitted.

It's because of Ohm's Law. Any sophomore-level electrical engineering student could answer this question immediately.

Until I see someone defining a representative example and running the numbers, I'm skeptical of their DC vs AC commentary. I say this, because I was guilty of this exact shortcut thinking (in another comment). But I paused and thought to myself "I should run the numbers before just repeating the usual voltage drop criticism". So I compared scenarios and it depends a lot on the topology, lengths, costs, and situation…

>Sure, a whole house system doesn't typically make sense, but I don't think that's what people are really talking about. I think people are interested in hybrid systems; e.g. DC power supply for each room.

I completely disagree. Where exactly are you going to put a power supply in a room? Make a special electrical box for it? Won't it be unsightly in many rooms, or need some huge special panel that looks like a breaker panel? The comments I see seem to be advocating a whole-house solution, where a power supply is mounted in the breaker panel to supply LVDC to the whole unit. But this makes no sense for several reasons, especially the voltage drop.

>I don't know if you meant it, but the sentence about "any sophomore level electrical engineering student can solve this" can easily come across as dismissive. I also think it gives too much credit to sophomore students. :)

It's supposed to be dismissive, because this whole discussion is a bunch of software people trying to make up solutions for a perceived problem when they obviously don't know one of the most basic things about electrical theory, which makes all of their solutions unworkable. It's like a bunch of people trying to make a new kind of personal vehicle to replace cars when they don't even understand Newton's Laws. It's really annoying, because I see this kind of discussion pop up every so often, over many many years.

I have another comment here I don't feel like copy-and-pasting, but basically this whole discussion is silly because people are trying to make a solution using a very expensive power supply to fix a problem they see because they're buying cheap $2 light bulbs that burn out quickly, instead of just buying light fixtures that were properly engineered in the first place. With modern SMPSs, you're not going to get any kind of benefit by centralizing the power supply to drive individual LEDs, you're only going to get problems. LEDs need a driver circuit to provide constant current, and that means the power supply needs to be matched to the emitters and kept very close to it.

Re: There's something off about LED bulbs

#905

Post by herbst »

formerly_proven wrote: post #24

There's a lot wrong with LEDs in general and retrofit (E27 bulbs) in particular. In no particular order - LED emitters driven hard for cost reasons, age and fail quickly - Power supplies driven hard for cost reasons, age and fail quickly - Poor CRI and SSRI - Flickering - Dim-to-warm is uncommon - Poorly designed power supplies that age and fail quickly - The same light quality is vastly more expensive to achieve wit…

I replaced nearly all bulps with WiZ bulps more than 2 years ago.

- I don't see flicker on any of my cameras. The light is actually really nice for filming too.

- The price is way less than hue (I own a few, and don't think they are any better)

- I get way more light per watt than with any other bulp type. Not sure what you mean with luxury.

- I love that each of them has an independent API on their own IP. Works perfectly for my smart home design.

I've had several cheap (in build quality, not price) bulps fail on me meanwhile. Not a single WiZ had failed so far. As said I own some hue too, but I wasn't willing to spend over $1000 just on bulps for my house but then I found the WiZ brand.

Not sure if am just lucky. But I really enjoy multicolour plus warm and cold LEDs in the whole house.

Re: There's something off about LED bulbs

#906

Post by dredmorbius »

Turskarama wrote: post #816
brianwawok wrote: post #789

Earlier quoted context omitted.

Wiring up a house with 48V for lights and 120V for plugs would be such a pain. Pulling 2 different wires to every room. Weird circuit breakers. Yuck.

A lot of countries already have lighting on a separate circuit. It means that when something trips a breaker you don't lose all your lights as well.

Lighting (on AC 110v / 220v circuits) also typically is specced for a lower peak amperage than utility or appliance outlets. For US codes, generally 15A rather than 20A. Lighting may use 20A, but isn't required to.

Other circuits must be 20A, e.g., kitchen outlets serving appliances.

A summary of standards here: https://www.thespruce.com/common-electrical-codes-by-room-11...>

A 15A lighting circuit can serve up to 14 100W bulbs. Or 150 LEDs drawing 10W each....

Re: There's something off about LED bulbs

#907

Post by Dylan16807 »

ixtli wrote: post #886
fsckboy wrote: post #652

Earlier quoted context omitted.

I do have different memories than you about buying lightbulbs. I remember thinking 60-watt bulbs are frustratingly dim, 75 watt bulbs are a minimum, but what I really wanted every time was a 100 watt bulb, it just improves visual acuity tremendously. And my frustration with LED and flourescents, etc is that I can't find the equivalent of my good old 100 watt bulb; whatever the new rating systems are, it's all an excu…

Try a 1100 lumen LIFX bulb. Overpriced but you’ll get the brightness you’re looking for if you have a fixture it’ll be a fit for.

1100 lumens only matches a 75 watt. 100 watt is 1600.

Re: There's something off about LED bulbs

#908

Post by Dylan16807 »

ccooffee wrote: post #810
wrycoder wrote: post #653

Earlier quoted context omitted.

And yet I have a growlight that specs its output in moles of photons per second.

I had been unaware of measurement according to "moles of photons", though I suppose it's not surprising. I've never really understood what a mole is other than "we decided to pick this number as a constant multiplier when doing small calculations". Per wikipedia[0], there's a vaguely defined unit, the Einstein, which may be defined as the energy in a mole of photons. (The vague definition being because each photon ma…

It's very important in chemistry to deal with molecular weights and convert them into usable masses. You could try to deal with uholy powers of 10, but mole makes everything easier by turning 1 molecular weight into 1 gram.

Re: There's something off about LED bulbs

#909

Post by ThePowerOfFuet »

eimrine wrote: post #95
QuarterReptile wrote: post #2

Non-dimmable bulbs are the author's problem. First, bans on incandescent bulbs are foolish because they encourage defeatist foolishness like this article (as far as I can tell, for the sake of virtue signaling and modest acceleration of a change that was already happening.) The CFLs which preceded LEDs were really awful, especially for closets (where they'll linger for decades, given the low utilization of those bulb…

Non-dimmableness is only one of the problems. For me the biggest problem is that all LEDs are blue, despite of any light-filters. I can not use it in bedroom when I use to read books before sleep and in bathroom when my aestetical needs of seing bare body have been not met. I have even changed my place of living since Sodium lamps have been replaced with LEDs on my old street. And if I need a really bright light or r…

Are you saying that you moved to a new house because of a change of streetlamps outside your old house?

Re: There's something off about LED bulbs

#910

Post by xxs »

droopyEyelids wrote: post #669
xxs wrote: post #541

Earlier quoted context omitted.

The same topic about LEDs has so many entries on HN in the recent years. I have posted about it a lot. To add to the list - low power factor (usually 50%). - cheap passives, caps/coils - terrible heat dissipation, e27/e14 are no good target, but see overdriven again - close to no input protection (see power supplies, again), so motors totally wreck them with their induction kickback OTOH, constant (not over)driven LE…

We're mostly on the same page, but there are some caveats to buying the heavier bulbs, even assuming the weight is all heat sink- because that won't matter if the heated air has no where to go! An expensive bulb with a nice heat sink will fail just as quickly as a cheap one when you put it in a well-sealed can light or something else that traps all the hot air.

If one bothers to care about heat sinking, they might actually test the thing and opted not overdrive it. It's just a good totally layman indicator.

Funny enough most mains/350V DC, chips tend to have a limiting resistor for the current drive - lower resistance = high current. Most (if not all) have two resistors in parallel (for a better control, and less power per resistor) - desoldering one would greatly improve the lifespan for a minimal luminosity loss. So by picking a larger heatsink, they might picked a bit large value for the resistors as well.

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