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.
I found this while looking for a dimmable teardown from him, trying to decide if I should invest in dimmables for the church fixtures. This explanation from the other side of it, though, ended up being more useful, if it's still accurate.
That would be nice to see. It's amazing how far they have come in just 5 years. I currently have a few fairly expensive "LED compatible" dimmer switches and modern "dimmable" LED bulbs in my bathroom and a few ceiling fans. I'd love to know how they work compared to the old style dimmers and last generation LED lamps.
Dammit Gummel! I did it again! Not as joke to myself and in honor of your awesome icon, but because I forgot! My screen is wearing away on the left. I keep forgetting. Oh, Crap! I want to know how to dim LEDs! Shit! There is a hair on my screen.... ;-)
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. 😎
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.....
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.
Top Tip: Hang your freshly washed linens on the fan's blades. This will slow the ceiling fan down, dry your clothes, freshen the air, and moisturise your face at the same time.
I doubt there are any semiconductors in a ceiling fan. The main reason being that the typical motors used in them (induction motors) can't really be "dimmed" by just chopping the AC. Usually the speed is controlled by switching between different capacitors.
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
I've recently replaced a handful of LED bulbs within the last year that failed in 2 years or a little less, marginally longer than the 40 and 60 watt incandescents grew up with and loved and certainly much shorter life than the manufacturers claimed. The bulbs that failed seemingly early were used in enclosed fixtures meant for 60 watt incandescent, so heat build up could have been an issue, since LEDs prefer a cooler environment.
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 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.
Uh, what? PoE is for powering remote network devices. Do you mean EoP as a communications method? Because that' still way to complex for a consumer grade light bulb. I'm thinking something more akin to "coax" SPDIF audio, but containing dimmer levels. Still insecure in that anyone with access to the wire can feed dummy signals, but far simple enough that a purpose made chip can receive it and process it without having an embedded Linux system (ala the hackable Philips bulbs).
well, often the light bulbs themselfs dont have WIFI but the controller of them has, but the controller - lamp is based on other protocolls (Ikea trådfri and philips hue).
There already are standards for controlling devices over the power lines. And they have exactly 0 security. All commands are sent in the clear, no encryption or signing. I too hate the bluetooth/WiFi controlled light bulbs, but without developing a new standard and somehow convincing everyone to adopt it, it's probably the best option security-wise.
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.
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.
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.
I know Lutron have a device that replicates a resistive load without the need for using an incandescent lamp (which will blow in short order anyway). You'll need to terminate it in a suitable maintainable location, but it's a permanent fix.
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 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.
We're probably gonna end up with USB lamps and most wall sockets will just have a bunch of USB sockets instead of AC, and it's gonna take some work to run anything that requires AC at home.
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.
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.
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!
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.
@@bigclivedotcom Well, the new dimmer works well, except... The hard on/off switch in the new dimmer solves the eternal glow problem, but now at lowest dimmer setting, one LED spot will light and the other won't. However, flipping the switch on with the dimmer slider set midway lights both lamps reliably, and then they can be dimmed down to a lower level. There is a programmable setting to adjust the minimum dimming level and that too would solve the problem, but the lamps are not dim enough when this level is adjusted for reliable startup. As you said in the video, two completely incompatible lighting systems. For now, we're close enough.
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.
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.
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...
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!
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.
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.
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!
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.
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.
With COB and filament technology low voltage high current DC is not a concern anymore. Mains AC can be rectified and fed into long chains of series LEDs controlled by a high-voltage buck regulator with PWM control. How to control? It's a matter of application. Choose from DMX, DALI, existing WiFi network. Something akin to homeplug ethernet might be interesting for domestic applications
Pretty much a noob at electricity, but how would you do this? Doesn't DC voltage drop over long distances with a decent amount of current? Seems like each light would be receiving differing amounts of voltage along the way through your house, so I dunno. Would you have the central transformer run all the wire at something like 12 volts and then have regulators at the base of each light?
I have lit a bar with about 15 meter of 12v ebay led strips, coupled with cheap pwm dimmers and a leftover computer power supply that is safely tucked away behind the audio rack. The whole thing cost about 25 euros.
Nice! I think one day houses will be wired with normal 110-220 VAC and some D.C. low voltage runs, maybe like USB type C that determine how much power is needed and set themselves to that level, if they can.
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!
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.
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...
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.
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.
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.
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.
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.
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.
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.
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.
Shouldn't we change the way we distribute energy throughout the places which we live in? I mean...leaving the mains for household appliances but develop new standards, for lighting, now that led replaced old tungsten filament lamps? Something like a breaker that feeds a control unit that gives out 24V= o 12V= for all the "lighs line"? This way LED lamps would have much simpler circuits since there is no need for transformers, rectifiers and so on, leaving just some resistors, maybe better lamp life (since you are not feeding it with 230V and spikes are unlikely to happen because of the smooth and stable current supplied by the control unit), complete dimmability and so on. What do you think?
I design Phase dim LED Drivers for volume manufacture. The one thing you forgot to mention is that it's the dimming system from hell. One further issue (of many) with triac dimmers is that diac can have different trigger voltages in each direction, so phase angles may not be symmetrical = 50Hz flicker which is even more noticeable than 100Hz. I could go on forever about the technical challenges, but I won't. The only true way to do this is to have a twin stage driver with advanced digital control. But such a circuit is very large with 40 to 60 components, generates more heat and is very difficult to fit into a bulb housing. There is also a USA flicker standard IEEE1789:2015 which if eventually adopted may make 99% of phase dim product obsolete or even illegal. I would also postulate that the terrible effect on mains currents ( very high THD/Harmonics) could be outlawed in future. Someone has commented... can you make your explanation more simple. The answer is no. Cheers, I enjoyed your video Jerry Senior Designer Harvard Technology
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.
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.
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 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).
Might as well just set the dimmer up for LEDs and keep a couple extra for the faulty ones, my experience with LEDs is that if they last the first 24h then I haven't seen one die yet, even the el cheapo ebay ones i got many years ago.
You wouldn't want to have your PWM driver far away from the LEDs. Ideally you want to keep that loop as small as possible otherwise you'll have huge EMC issues.
+Sander Deryckere I think the industry's attitude towards is really dumb in general. They think everyone is stupid with a "well, I have these sockets so I need to get bulbs the fit in them" logic and can't get past that, so they optimize for this. Making lightbulbs out of leds is remarkably foolish to begin with. Bulbs were invented for incandescent lighting. The design concentrates heat, which was good for incandescent bulbs to keep their filaments hot, but is the worst thing to do with LEDs. They should be making large surface lamps with diffusers at the very least which could deliver soft light instead fo the harsh piercing light of bulbs, and also would cool ideally. And would also make the problem of dimmers mute, because they should come with their own, built in dimming capability They should also put efforts into LED strips, an lamps/lighting based on that. We only have the cheap 12V strips which burn a third of the energy with resistors. And which are so crappy that they're noticably dimmer on one end on a few meter scale if you drive them only on the other end. Plus they look crappy by themselves so you need to buy aluminium profiles with diffuser plates for them at the price of gold (almost).
+Sander Deryckere Oh, yeah. More on the topic. You migh try a capacitance in series for dimming, which might work. You could switch more than one capacitor to get multiple levels, but of course you wouldn't have continuous dimmability.
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.
Yeah after typing that reply it did cross my mind that rheostats probably get a tad warm, and probably wouldn't be safe to embed in the walls of someone's house.
Reminds me of my internship where the speed of a three phase motor in a printing press was changed by switching massive resistors in and out. There was an entire wall stacked with them. Mind you this was just around 4 years ago!
Sounds like an old machine. The resistor banks are less efficient, but I bet that machine lasts longer and gives less trouble than one with electronic motor drives.
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.
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.
I have a cheap LED bulb with capacitor dropper and a simple switch with a neon bulb in parallel built in and when I turn the switch off the LED bulb dims down from 30W TL-D brightness to 1W fluorescent night light level, it has been operating like this for months and doesn't look like it's going to die anytime soon. So here's a thought: is it possible to use a neon indicator light in parallel with the dimmer to make it work on some LED bulbs?
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?
Idea: It seems many non dimmable LED lamps can be dimmed by a capacitor in series. Do you recommend this? Would it even be possible to use an adjustable capacitor to dim those LED lamps? Thanks for the great video!
I'm a bit late to the party but since Halogens seem to have disappeared those dimmers I bought for a £1 in flockdown were discounted for a reason. Meh. I saw Great Scott made a little dimmer the other day. Not exactly easy. Do you still stand by using funky, remote-controlled bling LED's in 2022?
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.
Hmmm... I have no experience with AC so it may be an obviously dumb idea, but why not just put a huge capacitor after the bridge rectifier so it literally smooths out the chopped sinusoidal input? Would it be too expensive or is there another reason?
One problem has been the lack of a neutral connection available behind the wall switch. Triac dimmers rely on the load having a sufficiently low resistance to 'see' the neutral at the other end of an incandescent filament, but with LEDs the high (and non-linear) resistance makes things unstable. When I first saw wall switches with the neutral passing behind through a connector block I thought it was lazy wiring or a failure to understand the 'loop-in' method, but with the neutral available behind the switch, many options become available for the future whether it be 3-wire trailing edge modules; 0-10V; Dali; DMX etc. One problem when building new houses is predicting whether a proposed new lighting system is about to become obsolete. It's safer to just specify standard 230V switches or triac dimmers, but at least with a neutral in the switch, some future upgrades are possible. Could a standard triac circuit be made more stable if it had a neutral connection available?
Unfortunately for a while the UK regulations specified that Live and Neutral should not be in switches together as it encouraged people to tap-in and fit sockets next to them.
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.
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.
Recently I had to buy LED bulbs for my dimmable living room lamp [getting more difficult to find the tungsten filament type] and whilst the new LED says "dimmable" the buzzing is too annoying.
Unfortunately, some of us have the dimmers inside the fuse box... Haven't checked in a while, but last time I checked there was no replacement available yet that would drive LEDs properly. Especially with the weird wiring scheme those things employ (it's pushbutton based). Two problems with my setup: 1) Although that dimmer is rated for 40W minimum, my 8 x 5W LEDs don't work properly with this setup, and I had to replace one LED with a standard halogen spot just so I could turn the damn lights off. 2) It works fine with my dimmable LEDs, and while you do notice some flickering if you look straight at them, it's not really noticeable otherwise. However, they won't dim down all the way, like the halogens did. At minimum power, they're still a bit too bright for my taste. And they don't dim down to a warm reddish colour either, like the old halogens; it's just less bright white, not at all natural. After all these years, we still don't seem to have a decent LED alternative for the good old dimmable incandescent bulb...
Best option there may be to bypass the dimmers in the fusebox so there's a constant feed to the lamp holders, and then use remote controllable lamps or holder adaptors with the nifty self-adhesive flat wall plate remote switches.
That would be an option. Or I could check if Niko finally got around to making a wiring-compatible rail-mounted LED dimmer to replace mine. The wiring scheme is weird though: www.niko.eu/NIKO/Documents/PM005-70300.pdf (mine is connected with the pushbuttons on the neutral). Time to check their most recent catalog...
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.
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.
If they're going to develop new wallplates (that would be signalling the lamps over power or via RF), then instead of again switching all the LEDs on and off (albeit quicker this time, using high-frequency pulse width modulation), would it not make more sense to design the lamps compatible with a clean-slate dimmer-to-lamp protocol so that these "dimming 2.0"-compatible lamps would consist of multiple LEDs, and would only drive some of their LEDs, depending on what the dimming 2.0 protocol tells them?
So how is a C.L. Dimmer different? I haven't used one yet, they were kind of spendy a few years ago when I switched to led lights so I just removed the dimmers in our house. But what is the difference, do C.L. Dimmers even work? Or would we be better off replacing the lights we want dimmed with smart led lights?
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
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.
Peter McArthur First off, there's less paperwork. No need to pay for the license to use the Bluetooth patents, no need to get FCC approval for an RF transmitter, etc. Additionally, each device would be cheaper to make because you don't have to pay for the Bluetooth module itself. The power line communications protocol can run at something like 25khz, which is just above audio frequencies. Basically ANY transistor would work well enough at those frequencies. On the other hand, the microwave-band frequencies used by Bluetooth and WiFi (2.4 Ghz and/or 5 Ghz) require special transistors. It's also less expensive to implement on the consumer level because only need to pay for one dimmer controller per fixture, not one per light bulb. There's nothing stopping anyone from making a dimmer controller that can accept Bluetooth commands, either.
Do you think you could please make a video showing us in practical layman's terms what happens if you use an LED bulb with a dimmer? I thought you'd made such a video and maybe you have, but I couldn't seem to find one.
The Layman's terms as you put it... OK so a traditional dimmer will cause a standard LED bulb (non dimming type) to fail really quickly. Then when used on a LED bulb designed to be dimmed, the traditional dimmer switch would cause really bad flickering of the bulb. I have seen the results of both, and either effect is not good at all. Lowest cost option is to use a LED dimmer switch (most of them have a trimming adjustment of some kind), and a quality dimming LED bulb. This is not a perfect solution but works well with no flicker since you "trim" the switch to allow full range of the dimmer. The other option is to use a LED RF kit that has bulbs that use some sort of radio control, Bluetooth is the most popular one, since you can download an App that works with the bulbs. This allows you to control each bulb or groups of bulbs. Most of these offer all sorts of color options too. This sort of setup offers the most flexibility and can provide the best reduction in power consumption. Since you are not installing a dimmer switch in the wall that could potentially use more power then the LED bulbs would. With this setup you would only use a normal on/off switch. The main issue with this setup if the initial cost for everything, since the bulbs themselves are doing all the work. However since they are gaining popularity, the prices are dropping quickly. A year ago the Bluetooth bulbs were just over $40 for one, now you can find them for about $20.
I seen some bulbs that come with an RF remote control that allowed you to adjust the colour temperature and brightness and such, I thought they were good. I've been thinking of getting a couple of the LIFX bulbs but those are rather expensive.
Lachlant1984 You are absolutely correct there is all sorts of RF bulbs out there, the ones that come with their own remotes tend to be lower cost then the Bluetooth (form of RF signal) ones. The Bluetooth ones have the added benefit of not only having their own remotes (most of the time) but can also be controlled by certain things that uses Bluetooth like a tablet or smartphone for example.
Well, I went and had a fun adventure with a dimmer a while ago. First bulb I bought essentially strobed. It wasn't a flicker, it was outright strobing. That bulb apparently wasn't even a dimmable type, so I sort of chalked that up to me being stupid. Second bulb has been in the socket for about 2 years now, and it only lights up once the dimmer is about half way, but otherwise works fine. Hasn't failed yet.
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
Would pulse-width modulation (fitted between the bridge rectifier and the LED itself) not be one possible option for dimming an LED light? As I understand it, LEDs easily tolerate rapid on-off switching, and some battery powered LED torches or head-lamps already use PWM to provide different brightness settings. Another possibility: A miniature variac (directly rotated by the dimmer knob) fitted within the wall-plate, to adjust the AC voltage fed to the LED lamp. Of course a variac that small could only handle a few watts (maybe a few tens of watts at most), but LED lamps only use a few watts anyway, so that should work, should it not?
you know there are dimmable led bulbs, i just wonder personally, do they work properly with a non-synced pwm dimming circuit (constant pulsewidth modulation)? i'm planning to make a digital dimmer myself, arduino nano, optocoupler, dual output transformer (+ - + to have a "separate" supply for the mosfet and arduino) and 3 fullbridge rectifiers (or 2 if i opt for an SSR, basically a TRIAC with an optocoupler)
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.
All dimmable lights strobe. All of them :( please correct me if I'm wrong, I will be very happy finding one. I have tried nearly every make of 'dimmable' bulb and they all flicker, even the expensive Philips and Osram ones, some worse then others. Doesn't matter if your use a dimmer or not, or a traditional dimmer or a trail edge dimmer, even in a straight on off switch like a lamp they seem to strobe/flicker when tested on a slow record. The quick test I did was slow motion video on the iPhone where you can see the strobing on all dimmable leds. Even get strobing on all hallogens (they can all dim). However, a few straight non dimmable leds I tested (like both Philips core pro 11 and 13 watts were completely stable). I'm dreading to think that no dimmable leds that don't strobe even exist. Even if my eyes can't see the dimming, and only in very slow motion you notice it, I'm sure my migraines come from them. Has anyone else tried this iPhone test? I am completely wrong with how I'm testing or am I right and all bulb manufacturers offering dimmable bulbs ruining our health?
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.
The resistor is primarily to prevent a tingle from the base of a lamp or pins of a plug. It passes very little current in relation to the charge coupling through the capacitor.
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.
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.
Sorry mate! I did ask you the same thing. I've ordered so many off Aliexpress and it's been total hit and miss. Luckily the biggest batch I got worked well and have lasted ages. Who knows where I got them... There are so many factories that look identical.
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.
Here in the US we've recently seen some huge price drops in dim-able LED bulbs. I did a video reviewing a four pack from Meijers for $10, the dimming action is pretty good. And the day after I put that up the video, Menard's had a similar four pack for $8.
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
How do those filament-style LED bulbs work with dimming? There's so little space to hide circuitry, but they work BEAUTIFULLY with both the manual dimmer and smart dimmers I've used. They've got even more range than the incandescents used to have, and they don't even get particularly warm.
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
Look at LT3799 from linear technology... they already solved this problem. Any old phase angle controlled dimmers can be used to dim LED s fitted with that ic.
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... :)
What about replacing the old dimmer switches with variable voltage regulated power supplies and just supplying LED bulbs with clean, straight DC at a voltage adequate to the desired brightness?
maybe a stupid question, but could one build a compatible dimmer that just (e.g. via some sort of variable resistance, dropping or even filtered PWM to produce a fake sine wave from a rectified input for more fancy/smart/whatever solutions) lowers the voltage? or would the LED drivers try to boost (or buck less) that to the maximum LED voltage and randomly flicker? if so, maybe just ignore the fact those things have rectifiers expecting AC and supply them with (very fast) PWMed DC (so it still flickers, but with a few KHz-MHz instead of ~110Hz)?
