Philips dimmable LED bulb for $5


#Philips dimmable LED bulb for $5

so… not really dimmable, then?


Are you using the correct wallbox dimmer with it?

Actual Architectural Lighting Designer Responsible For Making LEDs Dim In Houses


Have a look at this:

A lot of the LED dimming issues arise from the various ways that dimmers modify (or not) the voltage. Standard incandescents lower the height of the curve, but LEDs need the full 120V signal and then cut down on the front (or back) half of the wave. This essentially turns the LED on and off 60 times a second to provide both dimming and the full voltage. Others require a separate control signal entirely.

It’s complex because everyone it trying to game the market share to lock you into their ecosystem. But you should think of it as a system, from wall dimmer to source. Swapping out one of the components without considering the other portions of the system will typically have adverse effects right now.


Yeah - you need to use a dimmer switch that’s built to handle LEDs. I have quite a few of them in my house (mainly using the now sadly bankrupt Switch Lightbulbs, but also a few of the Cree cheapies). No strobing at all.



My house was built in 2007, renovated (after a squatter built a pot grow there and left it messed up) in early 2012.

Not sure if the switches are 2007 or 2012 vintage; the latter might conceivably have been “LED compatible” if that is such a thing. But the ones in the master bedroom and the kitchen work fine with the LED bulbs I installed.

I have a mix of LEDs and CFBs throughout the house. The two places with incandescents: the guest bathroom (which has a CFB and two incandescents I usually leave un-screwed in unless I actually have guests) and on the top of the stairwell, in a fixture I would need an extension ladder to reach.

The kitchen LED floods are really nice. 260 watt-equivalents of light for 65 watts of consumption.


Deal is dead.

Or, alternatively, get lamps that work with the dimmers you have installed. :smile:

A lamp might fit into that medium base socket, but you must confirm how you’re modifying the signal from the dimmer. Manufacturers spend millions testing this stuff, they want you to be happy, but some of it is on the end user.

I always thought that the common dimmers are the triac/SCR based ones, that switch on at a certain angle of the input waveform, and the switching angle is what regulates the amount of energy going to the load. (SCRs switch on when the trigger pulse fires at the control input, and stay switched on to the moment of zero current going through. With 60 Hz this equals switching 120 times per second, as each cycle gives two half-waves.) For regulating the amplitude of the sinewave, an autotransformer or a full-scale power inverter would be needed, and there would be probably considerable loss on (and heating of) the switching transistors.

There are also dimmers based on transistors instead of SCRs, which can switch the trailing edge instead of the leading one.

There are also issues with the loads; conventional lightbulbs are resistive loads, but transformers for halogen lamps are inductive and the switching power supplies are usually capacitive.

In an ideal world, the compatibility chart would contain the waveforms of the dimmer outputs, and a reasoning why they are or aren’t compatible…

A document about different dimmer types is here:

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I put an old CFL in the hallway and it cast a blueish light as from an electric arc. My GF was like “Take it down! Take it down!” and I said “Doesn’t it just instantly make you want to kill yourself?” and she said “My god, it really does!”


If you truly want to geek out on these, there’s a guy who does tear-downs of such bulbs and aims various sensors at them to check for flicker and color temps, etc. It’s strangely addictive.


Now THAT is what I’d call a review!

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I ended up several of the more expensive Philips – the ones that look just like the Hue bit without the built in wifi / zigbee chips – for $8 each. They are far more tolerant than these ones. It was at Home Depot a week ago, and picked up several GE Link bulbs too but wanted something that was non-automatable, and cheaper, and had had better spectrum.

But they were REALLY cheap last week:

A couple of months ago, Home Depot was selling these for $3.47. I bought about 20 and installed them pretty much everywhere. Very nice bulbs.


Looks like they wouldn’t be of much use on harpless lampshades, either.

I think an adapter could be made…

“Common” is difficult though, so let’s agree on “tungsten” for these in your example. Sinewave dimming, where the peaks are actually modified is very high-end but definitely reduces any noise issues from these dimmers. We specify a lot of these in high end homes to prevent any filament hum from even being a consideration.

Triacs, as you mention, cut either the forward half of the wave (forward phase) or the latter half (reverse phase) to dim the source.
Forward phase or leading edge:

Reverse phase:

Now, you also mention transformers for halogen lamps. Halogen pretty much just means we’ve replaced the vacuum inside the glass envelope with a halogen gas, so the source can burn hotter with less wattage. Not all halogens are low voltage with transformers, but lamps like MR-16’s certainly are. But one can get a halogen lamp that works exactly like a standard incandescent but has an efficacy to be allowed to be sold under the latest energy codes. So if you hate CFL or LED like I do, go shop for a halogen and lower your energy while enjoying the higher color rendering.

But, back to transformers, there are magnetic (large coils of wrapped copper, heavy) and electronic (inverters that switch the frequency quickly, very light) and they also dim differently. Magnetics are inductive and need a leading edge to work, ELV are capacitive typically reverse phase. Unless they aren’t and are capacative and use reverse phase. This really depends on who’s making the transformers and means you need to read the fine print.

And finally we get to LED, who can sometimes use that forward phase curve, the reverse phase, periodically needs a secondary analog control signal (called 0-10 volt),loves to get a secondary digital control signal (DMX), and is smitten with pulse width modulation (PWM). This is manufacturer-specific for the source and is often changing as the chip and driver manufacturers modify things as quickly as possible to get things out on shelves. So even if you purchased the same lamp six months ago, read the instructions again before you leave the store.

But PWM is super clever and modifies the pulse itself, giving you quick bursts with more time between them on the “dim” end and then increases the “on” burst as you dim it up:

PWM is great for LED, as it has to maintain that arc across the diode and 12 volts is going to get it there and keep it there, but it’s not very common in wall box dimmers yet. Very common with anyone who delves into exactly who makes their drivers or people who have no compunction strapping an Arduino into a light fixture, but we’re still trying to work a lot of these standards out in the industry. I mean, think about it, we’ve been using LED for ten years now and still don’t have a standard replacement for the A19 bulb yet. Everyone’s always coming up with these crazy styles and hoping they catch on and hopefully prevent other manufacturers from stealing their market share.

TL; DR: Check your bulb’s instructions to get the right dimmer and avoid strobing. There is no magic bullet LED replacement if you don’t know what kind of dimmer you have.


Solution, don’t use older CFLs. Anything in the past five years or so is going to have a CRI in the mid-to-upper 80’s, which means it renders about 85% of the color spectrum. And make sure you get a warm color temperature, like 3000K. You probably had a 4100K or even higher, and those don’t even cross my threshold.

But there is zero money going into CFL R&D. Fluorescent and sodium vapor lamps are both fighting to be the top of the scrap heap right now. Fluorescent is going to be with us for a very long time, as it’s so cheap and easily available, but nobody is spending any more money on making it better or more efficient.


True that.

Sweet. How do they work inside? A direct waveform synthesis? Or an autotransformer? Or…?

I think the reverse phase ones are transistor-based. Triacs can be forcefully switched off but transistors are easier for it.

I am looking forward to quantum dot based phosphors. These could give nice tunable spectrum without the pesky dip between blue and yellow.

Also, a good light source is a metalhalide lamp. Brilliant white, with mood-uplifting properties for long winters.

Somebody should design a multistandard chip. Something that can control many common kinds of LEDs (a programmable current source, most likely), and has several inputs for brightness control (UART for DMX, ADC for the 0…10V, ADC with a filter or a digital input with numerical processing for PWM, SPI for wireless chips…).

I think that PWM in the wall dimmer would have the issue of requiring to rectify and smooth the voltage first; PWM on the AC waveform would not be so good albeit it would work somewhat.

There are days when I dream about getting the big vendors to send a few engineers each (and no managers at all, and a secrecy vow to not tell anybody who supported what variant so the managers cannot have even indirect say), locking the engineers up in some posh mountain resort, and not letting them out (like when electing a pope) until they come up with one consensual specification, whether the problem is a charging connector or a dimming method…

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Lutron makes a line of CF- and LED-specific dimmers. I’m dimming these awesome Cree’s with those (also still some halogens, FWIW) without flicker. In Vermont, the state energy-efficiency organization is subsidizing those bulbs in a very generous way – you should lobby you state officials to help that happen for you and your neighbors!

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