5 years later, and it seems like the newer filament type LEDs have found their best/cheapest compromise solution, which is to just use high-voltage series filament LEDs, linear regulator current limiting, and then solve the flicker effect by using longer persistence phosphors that just smooth out the flicker chemically instead of electronically. Simplest, cheapest circuitry, works with the existing TRIAC dimmers that stubbornly refuse to stop being produced despite tungsten bulbs being VERY obsolete, a tad inefficient because linear instead of buck regulation but it means they don't need a big chunky base to hold the driver circuit, and the pulses and overheating issues mean they last just as long as tungsten lamps so the companies can still make money! As for the issue of triggering the TRIAC, I have found a few lamp HOLDERS in the trash here in the US that include a small "capacitor to nowhere" that exists solely to make sure the TRIAC has enough inrush current to trigger, doesn't even need to be a BIG one, just enough to cause a 50mA spike for the usual BTAxx series TRIACs to fire.

4 years on, I’d like to hear how things have progressed! Maybe you’d consider doing an updated version of this video?

Your knowledge in electronics and your effort to post videos everyday is astounding! You should be honored as a national treasure

FYI: In North America we have PWM replacement wall-plate dimmers (for old phase angle dimmers). they work well with LED CFL and Incandescent bulbs. They can drive any load up to 150W, smoothly dimming from fully on to barely visible and cost only slightly more than the traditional units.

How odd, a couple of years ago I bought a cheap B&Q £9.99 dimmer switch and a dimmable LED bulb and it works great, no noise and no flicker. The bulb is a £14 Integral LED dimmable ILA60B22011D03KAIMA (3000K). On the other end of the scale, I tried a Poundland 3 watt bulb in my bedside touch lamp, it turned into a snake machine at dimmed times. Thanks for being awesome Clive. 😎

I just have to say, I have learned more from your videos than i have from my high school before graduation. I've been watching for a while now and I must say I really enjoy learning, even if it is random from my point of view since I am not required to be on a specific topic now. once I accumulate the income, I plan on trying some of these circuits myself but that might take a bit of time. thank you for the knowledge.

I know this video is from 2 years ago, but I just found it and it's so hugely helpful! I was trying to troubleshoot the flickering on a cheap Chinese aquarium led light. For the longest time I was utterly confused thinking they were doing some sort of half-assed rectification with the triac, but I never could quite make heads or tails of how that was working. Turns out it is pretty much exactly that leading edge dimmer you drew, and not a rectifier (which explains the flickering). Next step is to cut the dimmer off and wire up a proper rectifier and smoothing circuit. Thank you so much!

As tech support for a company who makes SCR dimmers, having to explain to folks why they can't just swap out their old incandescents for LEDs is one of the most painful things I have to deal with. Especially if they've already purchased a set of 500.....

I had this issue with a string of "dimmable" LED lights which flashed and had the sharp cut off as described in the video. The 12 LED bulbs only drew 48W on a 150W rated Lutron LED/CFL dimmer so I added one 60W incandescent light in an innocuous location on the string and the problem was solved with the full range of dimming and no cut off. Not exactly an elegant solution but the wife is happy.

Super helpful video as people transition to green LED lighting. New LED dimmers are expensive so I was tempted to keep the old style dimmers in a refurbished kitchen. But the electrician insisted we change. The new LED dimmers are not perfect as they don't go down super dim but they are trouble-free and are quiet. My buddy refurbished a big room with 20 tiny celing LEDs - every one of them died within a year, which was expensive and a pain to continually exchange "bulbs". The electrician kept the old dimmer so we can speculate on what caused his problems...

Hi Clive Your favourite store, Poundland, used to sell dimmable lamps for £1. About 3 times the weight of the non dimmable ones. They also only lasted about half the time of the non-dimmable. I think that 12v lighting in homes seems to be the best option with potentiometers where you need them. There you go , a national company just for you. Great show keep it up.

I'm actually so glad you've made this, because up to seeing this video it wasn't something that crossed my mind and I just assumed it was some sort of a resistor setup or something rather like that...

I recently installed VARILIGHT V-PRO DIMMER SWITCHES with Philips Warm Glow Dimmable LED. They work well. The dimmers are programmable for various modes and come on with a gentle 'boost' . The Lamps have a 'lightpipe' to simulate filaments and have two sets of LEDs (warm and cool) the cool LEDs shut down to 'warm' the light at lower settings. They will dim very low without flicker.

VERY interesting video! I wish I saw this when working at a store selling among lots of things light bulbs. I never got the hang of which LED bulbs where dimmable and why. Thanks for showing and explaining how complex it is!

Having discovered your channel about a week ago I didn't imagine I could get so interested in light bulbs! :-)

One of your best Clive! An excellent status report on this evolution!

I am using 3 brightness level LED globes, controlled by switching them on/off multiple times to get a dimmer light output. So at the first on state, they are at full brightness & each following power off/on cycle reduces the brightness level (twice in total), then they are back at full brightness at the third cycle! The globes did cost a little bit extra, but it is worth it!

Brilliant explanation how a basic AC light dimmer works!

I think it would be a good idea to simplify the LED fixtures to be *just* a string of LEDs and a current limiting resistor. Then the dimmer would rectify and supply the variable voltage DC to the fixtures. Lower voltage = dimmed. When the fluorescent fixtures were too bright, they made a dimmer for each tube. It consisted of one plastic cylinder inside of the other. Each was printed with black stripes. When the cylinders were rotated so both stripes aligned, the tube was half dimmed. When the stripes were rotated to cover most of the tube, the light was very dim.

I’ve been in IT for a little while. Around 30 years. Personally I’ve found the best way to eliminate as much security and application issues with Technology as possible is to subdivide your network. Create subnets for your wired and wireless systems. One for security another for your computers your children’s stuff. your TV’s and home automation systems, Hell everything you have you that can be broken up and subverted out can, and in today’s age, should be sub-netted out. it’s pretty damn big networks (that is he 192.168, 10; and the 172 subnets) just divide them up and use firewalls and routes to keep them from breaching one another. There are lots of ways to handle issues like these, but the best way by far is to “stop, think, plan and document, then implement and test”. But hey, that’s just me and this Texan tips his hat to you sir and all your work. I thank you dearly.

Thank you, I've spent ages trying find info about this, very well presented. Cheers

Great video Clive, been dealing with this issue recently. Currently split between replacing the dimmer with switches and using dual white LED lamps with a remote control+hub... or just putting in the most efficient lamp type that works with a dimmer.

Immensely helpful. We just replaced two incandescent spots with LED spots and they would not turn off. I'm sure it was the triac sustaining current in the dimmer. My solution was to replace the dimmer with one that has a hard on/off switch in addition to the dimming slider. Thanks Big Clive! Even a 4-year-old video is helpful.

Thank you for the very informative video. I too have been pondering a decent method of mains powered LED dimming. I have decided that I need only a few brightness level options (4 or 5) so will try a tapped power transformer. We are 230V here, so a transformer with a 0-115-230 primary and a 57.5V secondary and a 2-pole 5-position switch will give 'off' plus 4 'on' levels. Lowest on level is 115V primary tap with the secondary connected reverse phase in series giving 57.5V, second level 115V from the primary tap, third level is incoming 230V with the secondary connected reverse phase in series giving 172.5V and full level is 230V. The transformer needs only be a quarter the wattage of the lamp (from my quick mental arithmetic estimation). Marcus, New Zealand.

As an IT guy, I don't like the idea of light bulbs communicating over systems as complex as Bluetooth or WiFi. They are so easy to bugger up security... Look at what Philips did with their internet connected light bulb. A standardised, over the wire protocol would be fine. But I know that won't happen because its not as cool as an iPhone app to switch your lights on and off.

Fantastic Video Clive. Keep up the great work. Nick.

I think the real future of LED home lighting is in integrated low voltage. It solves a lot of problems to stick your LED driver behind the wall switch, and have low-voltage coming out of the ceiling rose.

I have led dimmable bulbs from a company called Mini Sun on sale on Amazon £5 approx each bulb. No flicker and good quality. Best led dimmable bulbs I have found so far.

Excellent and very accessible explanation. Thanks Clive!

Wow. Awesome, informative roundup. Thanks so much, Clive.

For my entertainment room I finally just went DC. Used led strips with built in current limiting resistors, IR remote pwm dimmer and a switch mode power supply. I have Costco dimmable Led bulbs in the wash room on a dimmer. The dimming at the low end is as described in this video. They come on at 20-30% intensity.

You are exactly right. The dimmer (as opposed to "dimmable circuitry") should be in the bulb or fixture, and receive commands via the power line. One simple command protocol is Blink'n'Dim. A short power interruption triggers gradual dimming or brightening, and another halts it. Technology to achieve this is described on ResponsivLED.com. As of this writing, no fixture manufacturer has embraced it. However, a 0-10V Blink'n'Dim Adapter is available on Amazon for fixtures that include 0-10V dimming capability.

Hi Clive, great explanation! The way I see it is the most effective way to control dimmable LEDs would be as you suggested have the dimmer panel be a simple low power digital control and just modulate a carrier on top of the power fed to the LED fixture so no changes in infrastructure or wiring are necessary. Then the job of PWM modulating the LED would be offset to the local controller that feeds the LED. You could even have one dimmer panel control multiple LED lights independently by utilizing unique addresses for each light. Yes this would add the cost of adding more complicated control hardware and software but with IOT and dirt cheap powerful arm processors I think this is where things are heading.

Who knew LED lamps were so interesting?That probably comes down to a thoughtful producer / narrator & the inherent complexity of LED systems.

The IKEA Lunnom lights (the slightly more expensive ones with the brass colored base) work really well with traditional dimmers. I was really surprised by the dimming range, and they don't flicker at all. Perhaps a teardown of one of those would be fun!

Thanks Clive, I've wondered about that for a while. A very clear explanation!

In my Electrical Technology class in high school, we built leading edge dimmers, and as an experiment, we put compact fluorescent bulbs into them, which was quite an interesting experience.

Thanks Clive, I appreciate the explanation.

Thanks again Clive for your, er, illuminating explanation of dimmables! I just revisited this, because I am coming up to a makeover in my flat in south east London. I have a couple of ideas I want to throw into the pot, and I may try them out if I can get hold of the necessary kit. 1/ What if bar LED units were used instead? The principle involved would be to coil maybe 50 or 100 LEDs in a spiral fitting inside a lamp housing. The signaller (=dimmer) would then be in the wall switch, and I presume the PSU (driver) would, too - some reworking of cables needed. Instead of trying to lower the light output of a lamp's LED array, you'd simply reduce the number of LEDs lit. There are kits around that could be used, and a selection of bar LEDs, although I have not seen them in spirals. This could be worked round, however, by cramming modules and crafty soldering. But, their light output might be an issue. Ribbon lighting a possibility. 2/ Another approach would be a bodge IMHO. I was considering say a dozen or more LED downlighters in my living room, but with two or three on a separate circuit. How to do that? Use half-wave rectifiers! All I would need is a double switch. The two or three downlighters could also be underdriven - my crude way would simply be to add resistors, just enough current to trigger them. This approach is simply to have a lot less total light coming out of the ceiling, rather than each individual lamp glowing feebly. Not as sexy, but all I need is not to fall over the coffee table! As a complication I would need to override the dimmed lights, but I think some extra circuitry would work, the simplest by using a relay. Maybe your fairground experience can point me in the right direction! Or you could do an update video...

led dimmers are now mostly based on pwm motor controllers with a few extra output smoothing components

Another fantastic video! Thanks Clive.

This is why commerial installations used voltage or current controlled lamps, running at 24 to 50 volts. They are connected to the mains via dedicated drivers and power supplies. The drivers themselves are dimmed using DMX, DALI or 1 to 10 Volt signals. One driver can control a numerical of leds, and a suitable PSU could feed a number of such drivers. Essentially the lighting is a low voltage installation. Direct mains dimmable Leds are for existing installations where rewiring isn't practical.

Really good explanation Clive, cheers.

I noticed that my local box stores now are offering fairly cheap dimmable LED bulbs and they now also stock a dimmer specifically designed for use with larger multi-led lighting fixtures of the type you typically see being used in kitchens, etc.

Interesting video. I've always thought that a dimmer switch was just a high voltage rheostat.

Great comparison explanation. What you propose as the future is LumenCache. Communications to driver from wallplate as a controller.

Your comments about the circuits you have reverse engineered are informative. I have a pair of 4 lamp lights above my 2 sink counter in my master restroom. The 8 lamps are GV (Walmart) equivalent 60W dimmable lamps that work well with a traditional angle control dimmer. Although they the rf noise may be high I have no indication of this noise. It seems that the power from the dimmer is rectified and filtered based on the fact that when you turn it off the light decays over a second or two. The non-dimable ones turn off much faster. What is interesting to me is that even though these lamps did not cost much more than the non-dimmable ones, they seem to dim smoothly from a low turn-on position to full brightness and back down to minimum. Maybe sometime I will open one of these lamps to see what circuits they contain.

The simplest solution for dimming LEDs would be to use DC power, and just use a suitable rheostat of somesort on a dedicated LED-only radial circuit, so rectify the AC into DC at the lightswitch, then use a variable resistor as the dimmer with an appropriately designed standardised (HAH!! Like that'll happen!) LED bulb in the light fitting, and there we have it... :) I will say though, I have seen dimmable LED lightbulbs used on youtube, fella in Canada (vlogginlife here on youtube) has dimmable LEDs on two separate relatively standard dimmer circuits, so they are in existence, just not from places like banggood, etc., where our favourite LED filaments tend to reside... :)

For all the elegant and efficient solutions I think we'll largely end up with highly optimised cheap versions of the last type you describe (using smart circuitry to bodge a good result with existing hardware), simply because so many people have built in dimmers and an aversion to screw drivers.

We just built a new office and all the lights are dimmable LED fixtures that use a switched 120V line for On/Off and a separate 0-10V signal for the intensity setting. Works great for a new installation but not so much for existing buildings/wiring. I dislike the idea of radio communication for the dimming as the airwaves are noisy enough as is. IMHO modulating the signal over the power sounds like a good way to go for old work installations as long as it doesn't interfere with other systems.

Fun fact: Leading Edge was a computer company that made 386, 486, and Pentium systems in the late 1980s and early 1990s. They had a few modems as well.

The long term solution might be to switch to 12 volt dc wiring for domestic lighting. I recently installed half a dozen Bonlux T22 E14 ac/dc 12V-24V, 2W SES clear filament LED bulbs (from Amazon) advertised for "RV Camper Marine, Truck, Boat, Solar Power" in wall-lights a wooden gazebo. I didn't want to get involved with mains wiring regulations so everything is fed from a 12 volt dc PSU housed in the nearby garage. The lamps are really good but are far too bright and despite the fact that they're advertised as non-dimmable, I decided to have a go at dimming them. I tried them first on a variable voltage dc lab power supply and they dimmed nicely, cutting off completely at about 6 volts. Feeding them with a PWM signal didn't work (as expected, because of the internal smoothing capacitor), but I designed a variable PWM circuit using a 555 timer and fed that into a P-channel MOSFET with smoothing afterwards (as used in a buck regulator). It works perfectly. The waveforms all look good on an oscilloscope and nothing gets hot. It needs a bleed resistor across the output to cope with low loads and the pot needs to be logarithmic so that the dimming is not all bunched up at one end of the scale.

As always +bigclivedotcom your videos are completely accurate and full of information. I sincerely thank you for what you do. I'm always pleased when I see your videos pop up in my youtube feed. :)

Clive, Every year I put LEDs outside my mates house and we can dim the LED's using an 3 or 8 channel control board comprising of a triac, A control chip, A few odd components and the input from the computer... Yes we do the sound to light for christmas but we dont use the american stuff. We have full control of the dimming of the LED's either strings or the RGB strips.

Interesting. Nicely explained and answered some of my questions. Thanks.

I use a variable buck DC to DC converter to control LED light in my room, works a treat. I made a box with the circuit in that sits between the light socket and light shade with a pot on the side, I just reach up and turn the pot

I too would like to see an update. I've replaced quite a few of the old bulbs with "smart" bulbs and I've noticed recently that there seems to be about a 2 year life span before thy start flickering, without any dimmer. So I'd guess the dimmer functionality you describe is built into the bulb? I had one replacement smart bulb that was on an occupancy sensor and it did as you described being very dim, so I had to keep that one as a fluorescent. I've had 3 different rooms so far (no dimmers) that smart bulbs have started flickering within a 2-4 year or so time frame. Seems there is a big difference in life span for smart bulbs vs regular LED bulbs, and certainly not what the manufacturer claims are

Here is some more information if anyone is interested. You shouldn't use leading edge dimmers with any tipe of LEDs, even those with linear drivers which swich how many LEDs are in series. Voltage spike is so big that they can't react fast enough and even small capacitances arround the board make a big difference. (I wouldn't use leading edge dimmers anywhere thease days because some of them make so much noise they affect celphone, WiFi, Bluetoth...) You can use trailing edge dimmers on most LED lamps with some kind of linear control as said in the video but the problem is not only flickering bacause of ON/OFF but zero cross detection too. LEDs are so fast you can see 0,5% jittering and with so much noise on the power lines these days zero cross detection is not that easy. (We set the minimum for this type of dimmer to 25%) so the jittering is not so visible, but it is still there if you look for it.) There are many different options for dimming but they normaly start with dedicated LED power supplys at arround 25W and up, they are a bit more expensive but you can get a good brand for arround 20€/$ and they last for years. We mostly use 3 types of dimming: 1.Push button (for old instalations where wires are already in place and you can't use low voltage lines (Short press is ON/OFF, long press is dimming) 2. simple potentiometer normaly 100k ( thease type of power supply are the cheapest and the best in general, the probelem is you should have a cable directly from the lamp to the potentiometer at least 20cm away from mains power). 3. 1-10V (If you want to control more than one light at the time and you can easily add WiFi/ Bluetooth to this line) There are many others like DALI,DMX,KNX,Bluetooth, WiFi, LAN,... but for now I would advise to just use them for playing arround and not controll the whole house on it because one day it fails and when it does it takes a week to set up again. Leave those to companies, shops, entertaiment and people with too much money xD

I went to home depot and looked at some sylvania / osram dimmable LEDs. Not only were they like $30+ each, but the display ones bothered me with flicker. Down to about say half power they seemed ok, but below that threshold you could see the result of the sinewave being chopped up. Said works with standard wall dimmers. No, no it doesn't. I was less than impressed.

Hi Clive, could you do an update on this subject. I’ve recently changed my kitchen down lighters from halogen to dimmable led and they seem to work fine on the existing dimmer that was in the house when we moved in 20 years ago. No buzzing or flickering from the lights or the wall plate. It used to buzz a bit with the halogens when on full tilt 9 lamps @ 50w each. I was actually surprised they worked having heard about issues with dimmable led.

As always a really interesting video, I've struggled for some time to get a good LED lamp and dimmer combination, I found that my Futronix IR dimmer seems to do a pretty good job with most dimmable LED's. However having recently installed some Philips Hue lamps, I really think that's the way to go, not only very smooth dimming but colour temperature control as well. Also lots of features such as timed on/off, sunrise/sunset effect (great to wake you up) and remote control (even from the other side of the world, should you want to). Trouble is, very expensive.

Of the solutions you posited, I see the powerline communications option being the most likely as well as the cheapest to implement. The dimmer proper would be the LED driver as it is right now, except the voltage and/or current regulation would have an adjustable set-point controlled by a low speed serial data stream superimposed on the mains power lines. By default, this would operate at full power (no serial data stream detected = full power, should be good for testing or "dumb" switches). The dimmer switch would place a low-pass filter across both wires of the AC supply, and superimpose a low speed serial data stream on the lines after the switch. To do this, the dimmer switch would have 4 or 5 terminals, 2 for AC input, 2 for AC output (with serial data), and probably one for grounding (just for good measure). The low pass filter and 4 (or 5) terminals on the switch are the important parts. They make it so you don't need to mess about with channel settings just because everything is connected to a common power feed Effectively, they prevent the serial data stream from back-feeding into the rest of the house's wiring, while letting the mains power thru with minimal losses. Choosing the serial data carrier frequency to be several 10s of kilohertz makes the filter design for this relatively easy (and therefore cheap). Here's how the wiring would work (it's pretty similar to how dimmer wiring works right now): LED drivers that are wired in parallel on the output of an LED dimmer control switch will be controlled by that dimmer and no other dimmers. LED dimmer controls that are in parallel can't cross-talk because the low-pass filters isolate the serial data streams from each other. Easy to understand set up, no messing with "was that channel 5 or channel 6?", and if you really wanted you could probably get special dimmer control units that would translate to/from various home automation control standards to this one.

Thanks Clive, I forgot about the way that dimming works when it comes to non incandescent bulbs vs LEDs in my comment on your previous vid.

Hi Clive, I've recently purchased a dimmable LED from IKEA (LEDARE E27 1000lumen £8) and paired it up with a V-PRO-IR From Varilight (screwfix (1220J)£15.99) It works really well and you can program the dimmer to a minimum dimming level that stops the LED light from strobe-ing and the dimmer has programable leading edge, trailing edge or Digiflux? modes, trailing edge is the default and works best with the IKEA LED bulb, I know it's not a chinese £1 purchase but it works really well. If it didn't cost £8 I'd do a bigclive on the lamp, perhaps when it fails!

One day lighting circuits will be low voltage DC, with the bulbs containing no electronics but the LEDs. Elsewhere will be a fairly beefy AC/DC transformer and the wall plates will just do PWM of the whole system in the room. Spraying RF around the house to control lights feels too inelegant and error prone - I've used cheap RF doorbells before, they're not very reliable and like to randomly go off. We have dimmable LED lights in some of our classrooms at work, and the wall switches are "clever" - press to turn on, press to turn off, hold to dim. Some of the bigger rooms have big switch panels with programmed presets to turn banks of lights on at set intensities. So we can press "1" to make the room full brightness, "3" for just the front lights, and so on.

The ceiling fans in hotel rooms would appear to be triac controlled - it's either full speed (too noisy/cold), half speed (annoying 100Hz buzz) or no speed (too hot). Either way it's impossible to sleep.

I got a couple of GU10 dimmable LEDs at B&Q for £1 (reduced to clear). I use one of them in a weird Ikea floor lamp, which has a dimmer that I don't quite understand at all. The dimmer has a slide potentiometer and a neon lamp. As you turn the lamp brightness up, the neon gets dimmer and vice-versa. With the LED, the dimming is a bit choppy. It takes the LED a few moments to realise (?) what it's supposed to be doing.. There's a choppy dimming and then it settles out. I like the fact it doesn't get hot at all, but the light isn't as warm as a filament bulb. Filaments get "warmer" (redder) when they are running dimmed, but LED just gets less bright. I think you're right about needing a PWM dimmer, but it would be nice if they could emulate the colour change of a traditional filament too.

I have Cree LED stuff on the most used lights in my house now, and all of them are very smoothly dimmable with a standard dimmer. Here in the US anyway, they're cheap. Around $4 for a 60 watt equivalent bulb and around $14 for the pot light retrofit. While I don't think power line networking is necessarily a bad way to go, I don't think it would catch on much because of the added issue of what would certainly become another format war.

Thanks a lot for the explanation, I've been wondering quite some time about dimmable LEDs. Your video made it obvious why both the dimmer and the LED have to be made for each other. I guess you could put the complete rectifying, smoothing and pulsing circuitry inside the dimmer. And only have a current limiting resistor in the LED bulb. Such a type of dimmer would still work with old bulbs. But it would make these new LED bulbs completely incompatible with the current situation. So it probably just ends up quite expensive again due to different standards. (and given that you can't risk people putting the LEDs in sockets that aren't rectified, it would need completely incompatible socket types again).

The football match I watched Thursday evening Hull I think, the flood lights were led as they were strobing them and flashing them in sequence before the match, very impressive led can be multi functional if you drive it correctly

Love your videos Clive! So educational. However, how do the dimmer compatible filament bulbs work you show in your thumbnail? I bought a bunch and they dim fine on a regular dimmer with no buzz or flickering.

Hi Clive, What if you rectified the mains to DC, and effectively drove each LED as a separate unit using a chip of some sort? So you turn the light on and x amount of the LEDs light, not bright enough, you turn a controller and x more LEDs light. What do yoy think?

Would a dimmer that adjusts the output voltage to be a percentage of the input voltage work better? It would probably have to be nonlinear for lighting, but it could possibly work for inductive loads as well.

You can now get dimmable drivers that convert phase angle to PWM for backwards compatability. the market is slowly catching up to customer demands. it's like they were so busy making and selling LED bulbs they completely forgot how Joe blogs is going to actually drive the things.

I've actually come up with an interesting LED dimming system. It would use a specific light switch module that would communicate with the bulb through the wiring. The bulb would have multiple sets of varying intensity LEDs. The wall switch module would have a knob connected to a potentiometer, the circuitry would then tell the bulb the intensity to light at. A low setting could use half the low-intensity chips, medium setting could use all the low-intensity chips, and the high setting would combine all the low-intensity chips with half of the high-intensity. And at full brightness, it would light all the chips. It wouldn't provide the same kind of linear brightness control you would get with a traditional dimmer, but it would be a simple and functional system that doesn't involve any flickering or burning hot MOSFETs.

You're right that dimable LED lamps able to dim from ordinary wall dimmers are very complex as for accepting an leading edge dimmer you need to design circuit to be able to take high inrush currents. Trailing edge compatibility is more simple as "all" you need is to be able to analyze the waveform and drive LED accordingly. That said I do find that both Osram and especially Philips do run very on ordinary small current LE dimmers - even single bulbs. They've nailed it as far as ordinary consumers go. Technically it's a bit of a hack but they work very well in reality and those two manufacturers lamp are audibly very quiet even on LE dimmers barely audible with ears 5-10cm from bulb. I have a 15-20 years old 24-240w plug in triac type dimmer and even a single 7w Philips on it works nicely. That said I'm looking for a small plug in TE dimmer instead as it's better for the circuitry none the less and even ear close to bulb they're dead quiet but oddly they're hard to find. Wall type TE dimmers are easily but also expensive for odd reason and not suitable for my use. If you have trouble dimming a dimable LED lamp all the way down you can put on more lamps or an active load. As you say the future is different but old school dimmers will still be around for a long time and so will compatible bulbs as many people are not ready for a smart system yet. Heck even Ikea's LEDARE are mostly dimable types. Not quite as quiet and smoothly working (without an active load) on cheap TE dimmers as Philips but working satisfactory compared to price paid none the less. In the meantime you can get various of smart bulbs - even cheapos. Flip switch off/on within a second and it starts dimming, again to lock brightness levels. Others just have 3 levels 100, 50 and 10%. But it doesn't stop there. Personally I've switched to Philips Hue for some of my lamps. Really nice to be able to control light even when you're not at home, having light fade on 5-10 minuttes before alarm clock screams, automatic front door/drive way lighting with more complex patterns than a simple digital timer etc. I can totally recommend both Hue and Osrams Lightify. A few lamps though I will not or can't switch for smart bulbs. That's where the Osram Lightify plug comes in as it allows to turn those on/off remotely and smartly without those costly bulbs (it also helps I can buy the Lightify plugs at a good price through my work) and at 16 amps 230v the plug can drive just about anything you want - not just lighting. For wake up I like the light at first 5 minuttes to dim up at 2200 K (got the ambiance version in the bedroom, no full color able to go to 2000K as I find those way too expensive) then the next 10 minuttes fade to ~6000 K and finally over the next 15 minuttes fade to ordinary 2700 K. Mostly I wake up by the light instead of a screaming alarm clock and it's perfect to wake up on while reading news on tablet etc. For my front door/drive way I only got the cheapest white hue bulbs without any adjusting except brightness. Different pattern for weekend and work days and different light levels for different parts of the night/morning as some parts of the time you really don't need a blasting full light - just enough to see an make house look alive while on other parts of the evening/night - weekends etc. when you risk drunken people wondering around they get more brightness. So yes I'm very well on to adapting smart lighting :)

I had a setup of a basic dimmer and a Wilko LED bulb, and although it worked pretty well dimming wise, when the bulb wasn't on max power the bulb would emit a high pitch buzzing sound, although not too loud it was annoying.

White LEDS are actually ultraviolet LEDs with a phosphor layer that converts the ultraviolet radiation into visible light. The phosphors have an afterglow similar to the afterglow of an incandescent lamp filament, greatly reducing the flicker when driven with 50-60 Hz mains power.

which is why i put a 'ballast resistor' in parallel with the bulbs, just a pair of 3Kohm 10w ceramic power resistors in series is all it takes for 120V it also heps to lesser degree with CL rated dimmers in some cases

have to say have dimmable gu10 leds in the livingroom and a led dimmer from tlc direct, no noise and no problems, looks great and saves a fortune in electricity ;)

A lot of the commercial LED drivers don't use PWM to dim these days. They control the DC current to the LED strings

My old dimmers were a rheostat style. Good old wire wrapped dimmer no electronics required

Superb tutorial !

Great video and Im not tabbing on to ebay buying something for a change :) Busted some dim able myths Thankyou

My perception is that recently, it is harder to find LED bulbs that are NOT dimmable. Most of the LED bulbs in the local box stores are dimmable. They do require a special dimming switch which is LED compatible. I had a "traditional" dimmer and tried it with some "dimmable" led bulbs and noticed what was described by Clive - the lights flickered and made a humming noise. Since we can no longer purchase tungsten bulbs, I bought some more expensive (but supposedly longer life) halogen bulbs. These could dim, but they hummed worse than the LEDs when dimmed. So much so that I finally gave in and replaced the switch with a Leviton LED compatible dimmer and installed dimmable LED bulbs. No hum and no flickering. The LED bulbs I'm using are relatively cheap from a company called Ecosmart. The only complaint I have is that the led bulbs don't come on right away when turned on - there's a small delay which is short but noticeable. Also, the dimmer setting has to be at around 50% for the light to come on, but once the light is on I can fully dim the light. Hopefully one day +bigclivedotcom will be willing to tear one of these down. Would really love to see a Leviton brand teardown.

Clive - something you've mentioned in a couple of videos. That "discharge" resistor isn't only to prevent the terminals of the appliance giving you a tingle when you unplug it -- though it will do that -- it's a key part of the dropper power supply. Essentially, it slightly reduces the voltage across the dropper capacitor so that less of the mains voltage is dropped, and so more mains voltage is available to the load. (It's a significant term in the dropper impedance.) Try removing it from something; I suspect it'll stop working or work at greatly reduced power. And it'll give you a tingle.

Before triacs were available the PA dimmer used a SCR across the + / - of a bridge rectifier ! ( I have one and it still works ! ) .. the colour changing LED lamps use PWM and a remote controller ... a small step to " beef up " the lamp driver to supply big LED room lights , using similar hand held controller ( then remove your room's triac PA unit , fitting a normal on / off switch ? ? ) this must be the way for the future ?

Thanks for an excellent explanation. Maybe it's just me but in my mind the trailing edge would be the first example and leading the second thinking it's like an airplane wing. The leading edge would be the front of the wing starting from the front edge and the trailing edge the back half. Hence the leading edge would ramp up smoothly.

According to the latest technology I've seen, the dimmer module varies frequency, the supply to the LED is rectified to DC so the LED does not care about the frequency but......... Their are two (glass or plastic )envelopes around the LEDs with a gap for a substance which becomes less opaque (more transparent) at higher frequency controlled by the on board electronics.

interesting video there is a very good dimmer for led lights a phase adaptive dimmer works from 2 to 400 watts and gives no flickering with the led I have tried

Hi Big Clive! Do you know whether the pushbutton electronic dimmers work in a similar fashion? I have a couple of Lutron Maestro dimmers controlling LED can lights. I found that these dimmers can really dim those LEDs low, like down to the point where they start looking slightly green, presumably because the phosphor isn't getting excited enough anymore.

BigClive, what is the magic inside an LED load regulator (such as the Varilight GlowFix Regulator) that makes dimmers behave better with LEDs? Is it just a very expensive resistor or a more complex capacitive dropper?

Clear as mud!

I Suppose this also applies to the beefier theatrical dimmer packs. They replaced all of our house lights with the cheapest 'dimming' LEDs they could find as part of an eco-friendly initiative (never mind the fact they didn't even touch the 1KW Halogens and scoops) They've replaced dozens of bulbs that had a failure mode of dying, or my personal favorite, becoming a strobe light.

There are now several intelligent dimmers on the market that work with leading and trailing edge plus resistive they either auto sense or you program it by switching it on and off. you also set the threshold you want as the lowest as different bulbs have different on thresholds.

I have some Cree dimmable bulbs and they seem to work well - wonder how long they will last as I run them at about 75% all the time

I have a new Philips R7S LED Dimmable working perfectly with a Legrand wall Dimmer. I have tried a Philips and other branded G9 dimmable with ceiling fan light but it doesn't work properly

Since you have LED lamps with and without the drivers, that makes it a mess to try and work around it directly from the supply. As you said, if it has a smoothing cap, you can't really do anything, since the buck driver would just work harder to output. So isn't the problem coming from more of a "missing standard" on what an LED lamps contain? So making a matching pair of dimmers and dimmable LED lamps, would work the best?

This is a pretty good explanation, however is is somewhat "Clive-centric". Here in Australia, the use of capacitive droppers is pretty rare, as those lamps don't comply with EMC or power factor standards. Also, the use of PWM is not the easiest way to control LED brightness, nor is it the way that dimmable lamps are controlled. Modern chips adjust the output current, and they internally handle power factor as well. A single-chip buck with current control and PFC is extremely cheap with low component count.

Huh I just learnt something new, I thought dimmer switches were just variable resistors. Instead, they work more like analogue PWM. This explains why the one in my house made angry buzzing noises - until I removed it and replaced with with a normal switch so I could use LED bulbs in the room.