Dimming LED lamps with ordinary dimmers.
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- Опубликовано: 15 май 2024
- Using a traditional phase angle control wall-plate dimmer (the usual type) is just a terrible way to dim LED lamps. The rough chopping of a 50/60Hz sinewave with sharp voltage transitions is very hard to convert to a proper smooth and flicker free dimming of an LED lamp over a decent range. LED lamps also provide a very low load with sudden drop-off of current which can make ordinary dimmers very unstable.
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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?
Yes
Yes please!
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.
Yeah
Your knowledge in electronics and your effort to post videos everyday is astounding! You should be honored as a national treasure
I thought there was a hair on my screen, nice picture!
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.... ;-)
I also fell for your icon. I am amused.
One of your best Clive! An excellent status report on this evolution!
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.
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.....
Ezra Knickelbine I’d imagine that would be a nightmare. Almost a don’t shoot the messenger type deal isn’t it?
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'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...
Having discovered your channel about a week ago I didn't imagine I could get so interested in light bulbs! :-)
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!
Brilliant explanation how a basic AC light dimmer works!
Thank you, I've spent ages trying find info about this, very well presented. Cheers
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!
Excellent and very accessible explanation. Thanks Clive!
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. 😎
Fantastic Video Clive. Keep up the great work. Nick.
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.
Thanks Clive, I've wondered about that for a while. A very clear explanation!
Wow. Awesome, informative roundup. Thanks so much, Clive.
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.
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.
Thanks Clive, I appreciate the explanation.
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.
agree, IOT = security disaster.
. . power over ethernet is already here
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.
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.
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.
Genius top tip :)
Actually these things are adding windings at different angles, but I agree on the effect
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.
And render all your freshly washed linen filthy from all the dust that your ceiling fan picked up :p
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.
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.
led dimmers are now mostly based on pwm motor controllers with a few extra output smoothing components
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!
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.
Another fantastic video! Thanks Clive.
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.
Really good explanation Clive, cheers.
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.
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...
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!
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. :)
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...
Interesting video. I've always thought that a dimmer switch was just a high voltage rheostat.
Interesting. Nicely explained and answered some of my questions. Thanks.
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.
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.
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.
Great comparison explanation. What you propose as the future is LumenCache. Communications to driver from wallplate as a controller.
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.
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.
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.
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.
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.
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.
It may have been the triacs snubber network passing enough current to keep the lamps lit. LED lamps will often glow with just microamps of current.
@@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.
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.
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
Who knew LED lamps were so interesting?That probably comes down to a thoughtful producer / narrator & the inherent complexity of LED systems.
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.
That's the problem. Trying to make a transition from legacy wiring fitments. It's also why we have lamp holders you can poke your finger into.
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.
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’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 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.
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.
Anthony Challis And potentially hackable by pranksters or worse!
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.
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
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?
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?
Maybe 28 V.D.C. with up to 4 amps per circuit. Each wall plate can contain a small cheap buck regulator down to 12 V. or less for dimming.
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.
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.
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.
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.
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.
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 ?
This video is great. Drove me mad when I couldn't remember the phrase "duty cycle"
Great info. Why can't the Led driver and controller be built into wall switch?
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
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.
Meanwell IDLC and ODLC are flicker free dimmable LED drivers
Great video and Im not tabbing on to ebay buying something for a change :)
Busted some dim able myths Thankyou
Could u or have you ever Torn apart one of those dual-element high-efficiency bulbs or (instant bright fluorescent light) that use an incandescent bulb on the inside to heat up the fluorescent element and switches off the incandescent inner bulb once it has reached some sort of limit. I always wanted to see how those work
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.
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... :)
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!
Now I really want to try the dimming stuff we sell at my job. They are not integrated into the wall plate but rather kid of dangling behind and you use a momentary lamp switch to control them. Would tthere be different requirements for star and ring mains? (I use LAN terminology).
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.
Why is powerline cheaper than Bluetooth?
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.
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.
My old dimmers were a rheostat style. Good old wire wrapped dimmer no electronics required
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?
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
Seems I've stumbled into a minefield trying to go led!
I mentioned on your other vid before I saw this, I have a Philips filament style bulb i picked up in Saintsbury's, saw "dimmable" on the box and thought I'd be ok, but the irritating buzz is there. Interestingly one bulb is much worse than the other, might try asking for an exchange to see if it's just a particularly bad bulb as the other one is almost bearable when not right next to it.
Is there a particular key word i should be looking for when searching for a suitable dimmer? I see a lot described as led compatible, but mention trailing edge, which is no good either? I can't believe there isn't a simple solution to this problem!
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.
Another possible solution could be to use some sort of circuit capable of lighting different amounts of small LEDs, giving you as many brightness settings as amounts of LEDs you have. that way the LEDs run the entire sine wave and only at full intensity do all LEDs receive power.
I have no idea if this is possible though (rookie enthusiast)
Great video about the led lamps. What about the dimmers that say they are designed for leds?
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
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?
Would love to hear your opinion on these now Clive, just ordered a dimmer compatible bulb from Philips for the sole purpose of taking it apart :)
Superb tutorial !
Clear as mud!
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 video could not be published at a more suitable time, exactly what I tried to read and understand :D thanks! :)
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?
How aout variable density lenses. Like a welders mask. No heat just like an LED ?
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.
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.
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