eBay mains voltage touch dimmer - with schematic
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- Опубликовано: 4 окт 2024
- Whether you should actually use a generic Chinese touch switch is debatable. They don't seem to fully understand electrical isolation much. A version sold by a prominent local supplier is more likely to be built to a safer standard. This module came with four wire nuts, which are rarely used in the UK.
The bulk of the work on the PCB is being done by a dedicated chip that is not the typical microcontroller. It has dedicated circuitry including an amplifier and filter for the touch input and timing for the triac driver. The use of a capacitor in series with the triac gate is to keep the power supply simpler, as it results in a short trigger pulse of reasonable current.
The data sheet for the chip has extra layers of safety on the touch input, both for the user and the chip. The extra components have been omitted in this design. The timing resistor is an odd value. Possibly a "safe" value for both 50 and 60Hz that ensures the triac trigger points are well within each half sinewave.
The triac is very small. Its rating is a surprisingly high 600mA which suggests a typical lamp rating of 60W or much lower with LED lamps due to the high inrush current associated with their circuitry. The most common failure with dimmer modules like this is the triac going short circuit when a lamp fails with a pulse of high current.
If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:- www.bigclive.co...
This also keeps the channel independent of RUclips's algorithm quirks, allowing it to be a bit more dangerous and naughty.
#ElectronicsCreators
Interesting that on the 'flipped' image, the component labels are readable! They must have anticipated that "Big Clive always flips photos of our circuit boards, let's make it easy for him!" ;-)
Yeah, that was weird.
OK I wasn't going crazy-er?
At 2:22 we can see all the component tags are mirrored, but the "Kai Shengyu" legend is the right way round. Very odd.
Ok so it's not just me.... Thank goodness! I thought I had gone crazy!
No SOS mode though 🤷🏻♂
Or the epileptic flashing 😥
Lol. That would be hilarious. The Christmas tree flashing SOS :-)
SOSOSOS :D
@@Lohiv 🤣🤣🤣
@@Lohiv Or the inverted version of SOSOSOSOS
I remember back in the 70s my grandma had one of those brass touch lamps. It was so sensitive that a fly could land on the metal and turn it on, low medium then high. She'd get so mad she'd unplug it. After a few years she threw it away because it annoyed her. lol
My aunt still has one, in her living room. It sometimes turns on or off by itself, and she likes to think it's her deceased husband trying to send her messages.
@@tncorgi92 , yeah i think my grandma's did that too. Maybe it was a ghost too?
any radio transmitter nearby will make them go nuts also, say a cb or ham radio and especially mobile/high power ones. like living by the expressway with semi's talking often. the lamps will continuously change levels every time they're operating. it could be cause by many other devices that transmit or leak RF.
Always wondered how the modern ones worked. IKEA had a display of touch dimmers and every touch pad gave quite a strong feeling of AC fuzzy voltage.
It only takes microamps to give a slight fuzz feel.
everything feels fuzzy in some places in thailand.
especially annoying for metal laptops. if you have a mac bring tape..
I would NOT be purchasing those...
All the ones I've ever used decades ago, and I've NEVER had one that gave a tingle. Such junk today... Sad
@@nik_kot With all the millions of old houses that don't have proper grounds, that sounds like a wonderful design. Maybe that's why my big desktop case used to give me a tingle.
@@nik_kot laptop power supplies are quite often two prong devices. It’s not so much that the ground is not properly connected as it being properly not connected.
As far as items like this from eBay I fall along the lines of The Emperor's New Groove: No touchy! Nooooo touchy!
That Triac (97A6) is rated for a On-State RMS Current of 0.6 A, that would imply that in countries with 220 volts AC it could handle up to a 132 Watt load and in countries with 110 volts AC, half that so, 66 watts. (I was about to ask, how much of a load before it is overloaded, but I looked it up instead, and posted this in case anyone else was interested). Thanks Clive, great video as always.
The 5 page data sheet of the chip manufacturer (TonTek) lists different values for 3 of the resistors, depending on line voltage. It also shows two 1N4148 diodes clipping the touchpad input. And other interesting information.
Was that a Freudian slip I heard 13 minutes into the video expressing how good this product really is in terms of the interference it can potentially produce (pun intended)?
Another good video from you Clive, thank you!
Zener diode, zeeener diode. Thanks Clive for the English & American pronunciations of this part. It drives me nuts hearing zeeener all the time!
the zener diode was named after its inventer Clarence Zener, who was american. So I guess the american way is probably the right way!
@@kevvywevvywoo You've got a point there. I guess it is a Zeeener diode after all.
"There are no standards on eBay."
That is one of the most truthful statements ever spoken. In a number of ways. LOL.
Same for amazon.
I've always liked proximity sensor's. In 1961 for an 8th grade science fair project I built a vacuum tube version using a 2D21 thyratron tube (valve for those of you on the other side of the pond) from a Popular Electronics magazine article. The IC version using a Triac does not seem as exciting as the glow from a tube, but I admit much more practical.
OTOH, the elements of a tube are more isolated from each other than any other kind of switch. It can't fail short, nor can it fail by connecting mains to the sensing lead or the lamp housing unless you break the bulb and twist the elements together! Okay sure, tubes get hot because heated cathodes, they're inefficient, but... they come with a free, cheery, warm night-light! ;D
Clive needs to make a game show to see how quickly different people can reverse engineer a complicated circuit board. Also, you have gotten so close to one million subscribers! Would be cool to reach 1,000,000 at Christmas.
I doubt it will happen that soon.
Yes it would be a great present for an amazing presenter. Tell all your friends to subscribe and pass the word around.
Shengyn the finest things come from there to bring excitement to your life and test homeowners policy’s
Nice looking thing we could do with adding a good "buzz" when the pad is touched a sort of Haptic feedback, but mains 🤣🤣 cheer Clive 2x👍
(not had a good data 💩for years😱🤣)
Best thing since sliced bread. No more fumbling when you are half asleep to find the switch, just touch any part of the lamp and it comes on. Brilliant.
My parents had a touch lamp when I was growing up. From what I remember, it would only go bonkers after a power surge or when the power totally went out. At some point, the touch module died, and my father had rewired it with an inline dimmer on the line cord. Now I'm tempted to pick up one of these modules and convert it back into a touch lamp... Thanks again for another great video!
Those things are hell on short wave and hf ham radio reception.
Excellent job. I've played with these dimmers for years and never understood them. Thanks so much 🙏
The coupling capacitor must be Y1 safety rated. A 3kV capacitor is not good enough. A Y1 capacitor will be designed to fail open circuit, never shorted and withstand a 8kV spike. Fortunately it's easy to add your own.
That "data shit" lapsus made my mind deflect toward toilets and think about capacitive flush actuators for some reason... Guess it wouldn't beat those IR ones but on the upside you would probably get that "fuzzy" feeling in a different context and some people might like it !
Ebay, mains and touch! Sounds like a good time!
Great video. Thanks to this instructional video, I was able to successfully operate it with a voltage of 110V. If you use it with a voltage of 110V, you need to change the resistor R1(68K) to 20K/2W and the resistor R2(1.5M) to 2.2M.
I couldn't resist watching this video as soon as I saw the title; "eBay mains voltage touch dimmer"; it evoked morbid curiosity by dumping dopamine into my amygdala probably. Had it simply said "voltage touch dimmer", that would have been different in a less evocative way. It was the inclusion of "voltage mains" that made me recall movie images of lights dimming during electric chair executions....
I have one of these for my X-Mass tree. The trigger is a mettle snow flake that it looks like a decoration
I use non contact capacitive touch dimmers, originally based on Atmel's Q-touch technology, to put dimmers or switches behind tiles. They have a range of about 10mm.
Mains powered ceiling lights dimmed from the bath tub..
But in theory, you could also use those mini doppler radar/microwave detectors as light switches.
First time i saw one was as a lift call "button' with two sensors behind solid marble, with leds glowing through the stone. Very stylish. A completely smooth flat surface as a switch. Just needs a sticker. 👍🏻😀🇬🇧
In older houses with bootleg grounding and often some 60V between neutral and earth, those touch dimmers might be fun...
Touch dimmers aren't the only thing you'll have fun with in a house like that...
since the touch works through the wire insulation you might as well have the touch wire fully isolated
Touch switch and mains voltage. That is an interesting combination.
What I really want to see is the touch/wireless dimmers which have no neutral connection. I understand how they extract their power - either by a very small current through filament lamps or by adding a capacitor across the lamp in the case of LED lamps. What I don't understand is how they derive the timing with no neutral as a reference.
They can easily detect zero crossing when the current is zero.
I had a lamp back in the days with touch dimmer I liked that lamp so much lol it's nice to have a new Video just before going to bed
As a Scotsman I always appreciate the datashit
Looks very hackable and useful thanks for bringing this to our attention Clive 😊
What I would be worried about is if these were referenced directly to the mains!
Loving the variety lately thank you :)
I remember building a Kit for a touch dimmer years ago in the eighties it had a touch plate made from aluminium foil which was stuck to the back of a standard electrical blanking plate, so you never touched any metal it worked great until you let the kettle boil no auto switch off on the kettle back then, so you got a kitchen full of steam and the dimmer cycling from off to full brightness for a few hours!
HealthKit in the states sold a touch switch dimmer kit, worked great and still have it, wish I could find the assembly manual for it.
@@Subgunman I still have my dimmer it even had a two-way dimming although I never needed it its really annoying when you cant find something I have a heathkit tuner amplifier that works great wish I could get a manual for it it has a couple of coils that got broke in shipping
No spark, no fumes, no zap. Where is your spirit of Xmas Clive ? 🎅
I once had a bare copper wire tacked into a chair rail around my room hooked into one of these touch switches. It made turning on and off the bedroom lamp easier in the dark.
Some of the "branded" ones a few years ago (meant for control of ceiling lighting via a receiver circuit) used an entirely separate stand alone transmitter and seemed quite failure prone in my case unless installed in very little used areas.
I ordered 6 of these to play with. I forgot all about them until you did this video! I need to drink less and err play more? With electronics :p
A long while ago I found a fancy cheapish touch dimming lamp on the side of the road in somebody's trash.
I decided to disassemble it and i took the module out and stuck it into a plastic outlet box and attached the Touch line to the ground of a three prong outlet and a phone jack and crock cable. Wired up with a two prong cord and metal face plate. This let me touch the plate to turn the light on or crock cable that went to a strand of cat cable with a loop on the end which wrapped around the cord of a desk clip lamp that I had clipped to a bookcase. This let me tuck most of the wires out of The Way and I could touch a wire by the clip to activate or the face plate or I could plug a phone cable in with a little break out to route a wire around somewhere more convenient.
After like 20 years the module finally died so I replaced it and it was far cheaper than I expected to just go down to the local hardware store. The best part is the outlet cover that I used was custom painted by my mom with a little Bugs Bunny figure on it and that's where it has lived since.
Considering that most of the lamps in the US are two prong whether it's metal or plastic double insulated or not… Three prong ones supposedly exist I have never seen one in the wild.
other than cable abrasion the only contact point is in the socket connections which is usually insulated with a cardboard insert that if in good condition is sufficient, and I have never scene one otherwise unless the whole lamp is soaked which you wouldn't want to use anyway at that point.
I have not had any issues and I find this fairly safe knowing what it is and how it works. although now I'm thinking what's three prong metal and motorized that I could plug in in touch to control speed hmmmm.
It would be a lot more interesting if all the wires were the same color and they all came out of a single hole in the box.
And all just twisted together inside.
Interesting chip that's been around for yonks, I found the Chinese datasheet that described 2 capacitors in the touch plate and another in English that showed 3 !...cheers.
Uh oh Clive you're Freudian slip is showing😁 most of these touch dimmers ARE $HIT, I used to work for an electrical contractor supply, we ordered a bulk box of touch dimmers I didn't noticed until later that there was a sheet with a wiring diagram with a note in BOLD TYPE, I wired one up for a customer plugged it in to test it as soon as I touched the lamp 💥BOOM, it blew the bottom cover off the lamp🤯the Chinese company had used the same wire colors but totally opposite, the note said unit will explode unless wired according to revised diagram, someone pu dekcuf at the factory and eh we'll just throw ONE sheet of paper in the box with a note on it, instead of fixing them, some of the chinesium products are dangerously amusing but you really have to be careful.
I totally wouldn't trust my life to how good some random manufacturer was at isolating the touch pad, lol.
Thanks for explaining. Greeting from Ohio USA.
I'm going to try to find the on-off only version of this. Any sine wave chopping wipes out the lower part of the radio spectrum, as you mentioned, and the majority of the radio stations I listen to are on AM, so no dimmers or noisy SMPS allowed in the house !
I was pleasantly surprised when I was scanning radio stations in my new used van that there's now a handful of am stations around me with music, decent music at that. Radio or not I think noisy power supply should be regulated and I hate it when I see people who go on Amazon and buy the $10 laptop charger that's a complete knock off and weighs less than a quarter of an ounce. The safety alone.
As a Ham radio operator I only use high quality switching supply’s in my home. The main issue is with the power grid here in Greece. Old and outdated insulators used on the high side feeds are always arcing over due to the salty moist air around most of the country. The corona discharges wipe out most of the HF spectrum and very little is done to rectify this issue.
I have 2 lamps which included dimmers which would not work with LEDs. I found replacements for the dimmer which switched only. I paid about £1 each + £2 shipping from China (EBay). I later found ones which dimmed but realised I didn't need them. The on/off ones have worked for several years without problems.
@@Subgunman so you're saying they need to call electricboom to install some full bridge rectifier's? HAHAHA to rectify the situation.
I still have my three 15 watt canadabra base bulb 'brass' touch lamp, bought at a flea market in 1992 or so. Still works fine, I haven't even had to pull it out and replace the assembly. Our last house, it would turn itself on during the night about once a week.
Stray EMI/RFI?
@@davelowets - possibly. I think that the lamp was just sensitive to small voltage surges due to the old power infrastructure in the area.
My parents had 2 of the exact same lamps in their bedroom and they would turn on randomly as well, especially after power interruptions/ surges.
My lamp would turn on sometimes when disconnecting/connecting the vaccum cleaner in the next room. Since it is a a new building with good wiring I'm assuming it was caused by EMI in this case.
Yess.. Let's take a look at the data-shit.. how often is it just like this ? 🤣..Again, great video , and always much fun !
I remember in the early 90's when I first saw a touch lamp. They were seemingly powered by magic.
I got given a faulty touch light by a neighbour to look at.
It had that exact module inside, the touch ring was under the upstand threaded nut which clamped it to the base. The whole light was made of metal, and it wasn't earthed, so I decided it was too dangerous to repair and return to them, so they got it back faulty.
There's a huge safety problem with this thing in that the circuit trace connected to the touch input almost certainly isn't sufficiently separated on the PCB from mains voltage traces. The 3kV capacitor should bridge an isolation boundary on the PCB.
Sadly, this is better than others.
Places like continental Europe don't have polarized plugs. I don't think China does, either. I wonder, do they have different circuits in their touch lamps or just instructions that read "Troubleshooting - If it doesn't work, flip the plug around."
Yeah what is the Chinese equivalent of "if you're dead don't call us"?
The latter. I had a touch-sensitive lamp ages ago, and we don't have polarized plugs. It only worked if you plugged it in one way.
@@kpanic23 Thank you. Rare is the definitive answer in the RUclips comment section.
Big Clive , you could do audio books ,you have a very soothing voice ...I like it ..
Simple and it works, pretty nice functionality too, but again, two 1n caps in series SHOULD be used in line with the sensor as a safety measure.
I put a touch light switch in our lounge that dimmed about 40 years ago. Still working.
I installed one of these in my room as a teenager that triggered by touching a large lead weight I had suspended by my headboard and during and intense thunder and electrical storm it turned on and scared the living shit of of me. I had been watching scary movies before bed. I almost had a data shit it scared me so bad.
I have Touch Sensitive dimmers installed. They’ve been here in my apartment for over 30 years. During power glitches the lights sometimes turn themselves on in the dining room or living room. That’s quite annoying especially when I don’t notice until perhaps the next day when I go downstairs and see the lights on many hours later.
"eBay mains voltage touch dimmer" Not having seen the video yet, I guess if you touch mains, your light will go dim, yes.
My mum got rid of her touch lamp, the cat would turn it on in the middle of the night by sniffing it. LOL.
Triacs are notoriously noisy on the Radio Bands.
On the flip side, these lamps are sensitive to Radio Transmissions, by keying the transmitter, the lamps go through their Off Dim Bright ETC every time the TX is keyed.
Seen it in a neighbours window. Naughty but fun.
Some PIR sensors are also prone to a UHF transmitter nearby. I once visited a relative in my Camper Van. Every time I keyed the UHF TX, ALL the outside lights came on at once in the street.
People going outside to look whos there....
You can use it with the COB LEDs that use no filtering and smoothing and purely resistive current limiting for the LEDs. It will flicker horrible but there might still be applications where flicker doesn't matter.
Actually bought 1 of these off of Wish for £1. They sent it in shrink wrap, instead of the pictured plastic casing. Installed it on a lamp, all the same, & it works. Didn't realise how unsafe they can be. May have to take another look at it now
Perfect for the bathroom lamp
I wbay'd one of these a few year years ago for a light project - and didn't quite trust it either - so had a look inside and noticed it had the rwo capacitors which allayed my fears somewhat ...
But adding a series resistor is a good idea for a bit more isolation - I shall do that !
Nice video
We had a lamp that I assume had something smiilar for controlling it. I found it annoying, and was happy enough to pass that lamp along to another family member...
A follow up video showing the resistor experiment (R3) would be nice.
I never thought of using a dimmer switch in series with Christmas lights. It could dramatically increase their lifetime.
Especially useful, not that the tungsten lamps are getting harder and harder to find with each passing year.
@Gazr Gazr Didn't the nasty flicker drive you insane? I can't STAND have wave rectified christmas lights. 🤢
@@davelowets You mean LEDs right? The flicker shouldn't be visible with incandescent bulbs.
Tungsten strings have made a comeback this year in the UK.
@@M4RC90 Ah, yes, I missed that part. I can't even find incandescent sets around here anymore
@@bigclivedotcom Send some this way... Lol 🍻
The 'kick' from a lamp burnout frequently fries these. I've put three of them in a friend's lamp.
I don't think it is the "kick" so much as being left turned on with no load after the bulb has burned out.
Yes you can use capacitive switches through plastic and pla cases. I've used 1mm thick pla to reduce sensitivity.
I bought some a while back,I just seen this so I opened it up my chip is a K101/2111tryed find Data sheet it's coming up as a photocoupler I'll keep looking 👍
I had a touch lamp as a kid. You could play with the ceiling fan in a different room and it would cause the lamp to turn on and off. On a totally different breaker even.
That may have been due to switching voltage spikes.
In touch sensing, You ARE the capacitor.
My LED lamps are glowing with an open switch.
The glowing is common with modern lamps. Especially with multiple switching positions due to the capacitive coupling between the switch wires.
They used to go crazy when radio or computers generated rf was around .People's lights would be going off when someone hit the PTT button on the radio
very interesting ty Clive.
Next you should take a look at an eBay Turbo Encabulator. Been wondering if the pre-famulated amulite housing is a worthy upgrade.
Absolutely! Spend the big bucks on it. The more, the better... Go for it!
Worth mentioning that there should be 2 caps in series, but they only installed one. But initially touching the insulation had the same effect. It is of course stray capacitance in series with the 4kV capacitor. It may be worth setting it up so you only touch the insulation Edit. I commented before the end of the video 😂
Bought a couple of these from Amazon one of our touch lamps had failed. Casing and conductor colours are identical to this one. PCB slightly different. Connected as per diagram and it worked a treat, however out of interest I tested between metal casing of the light fitting and a known earth and had 160v which seems rather alarming. I was going to retro fit one of these to a bathroom shaving light but no Way, in a special location!
Compared this to the matching other lamp which still has the original circuitry and it had around 20v.
The seemingly high voltage your are measuring may be because your test meter has an extremely high impedance.
Are we talking ghost voltage here Clive
As a radio ham,I have a touch lamp and it does generate a large quantity of noise,also when I am transmitting the lamp turns on and of because the touch wire act as an Antenna,no amount of suppression seems to work.
I normally use the non-dimmable version of this touch dimmer switch, for LED light bulbs. You Used to be able to buy these touch lamps in the UK, from the supermarket. I haven't seen them lately, maybe they're not compliant enough, due to the touching of the metal parts reference to Live. I have two, touch bedside table lamps. I replaced the dimming version of the modules, with simple on-off ones(from eBay, upgraded the triac for bigger ones) This makes it led compatible. I also added a resistor in series with the touch wire, for extra safety. In Europe you need to reverse the plug to get them to work, if the polarity of L & N is wrong.
It’s a pity that the Schuko outlets used in most of the EU countries are not polarized. In the States we use polarized plugs and outlets. On the blades of the plug you will see one of the blades that is a bit larger than the other and the outlet as well has one of the slot openings a little larger than the other. The smaller slot is always phase while the larger blade is neutral. The opening below the two slots is the ground (earth). Major reason for this design is that in the past electronics manufacturers started creating radios and television with a "hot chassis" concept where the chassis was connected to neutral. The hot chassis phrase comes from the fact in the early days plugs and outlets were of the same size allowing one to accidentally insert the plug into the outlet in reverse giving one a "hot chassis", this was a sure way to knock yer pants off!
Problem is that many dimmers are not LED compatible. Maybe that is why they stopped selling them.
@@michaeltb1358 maybe, but the touch module comes in both dimmable and non-dimmable versions.
In case anyone cares, the guy after whom Zener diodes are named (Clarence Zener) pronounced his own name "Zeener" (not "Zenner"). He won't mind if you pronounce it the other way, though; he's dead.
Reminds me of when Alec of Technology Connections made his go boom due to ambiguous wire colours, and his was sold in a store, dodgy stuff... :P
Hi Clive. interesting and thanks for the warnings. Nice of you to mention us Radio Hams, would you be one , I wonder? Again thanks and keep them coming whatever the subject.
Alas, I'm not a Ham.
I was expecting it to be potted.
Aluminium foil tape, for ducting, has vulcanized rubber adhesive. I use two layers, with the lower layer in contact with the "ring" (in this case). Added capacitance and shielding.
;)
I suspect that potting it would raise the price. Ain't no secrets in there anyway, so they only care about keeping cost down.
No, no, it's an eBay product. Data shit is appropriate. 🤣
My bedside light is a touch sensitive one, it has a similar module to this inside it. I run a wire from the metal touch surface to the top of my headboard so I don't have to lean over to turn it on or off 😂 coz I'm lazy like that. Always wondered what was inside the module, but keep forgetting to take it apart and see how it works. I tried mine with led lamps to no avail.. Must need a load between 40 to 60W I'm assuming, which is well above a 3.5 to 5W led lamp. Great explanation as always Mr C 😎👍
The triac usually needs a minimum latching current to stay on.
Ebay, mains voltage, and touch. Those are some words that should never go together.
You should explain that triacs are held on by current, not voltage. Makes no odds with a resistive load but important to know.
i got the exact same one to repair a lamp and tbh it looked a lot safer than the failed one i removed
I think “data shit” might be a more accurate description of some of these documents
Bought a wall switch/dimmer with a touch plate some 25+ years ago. Touch it and lights on or off depending on previous state. Touch and hold, dim/undim (is that a word?) from last setting and "direction". Really neat! Lost it when the landlord decided to "modernise" the building and I never found one like it since. Boo hoo!
As a HAM radio operator I know these are notorious for causing huge noise on HF bands and flashing the lamp on voice peaks when transmitting. Ron W4BIN
I was debating on purchasing two for our bedroom side table light, but then I remembered I asked a Chinese seller about another item is it earthed and the reply was what is earth? So I don't think I will bother, I need to find an English electrical suppler to purchase two of them? Thanks for the video, it was most enlightening!
There actually appear to be a couple of different "datasheets" floating around the internet for this.. One (which most closely resembles this circuit) appears to actually just be a one-page "how to" article somebody wrote up. There is another one which looks like it may be an actual datasheet from the manufacturer, but interestingly that one shows a very different value for that clock resistor (330K instead of 620K) but still doesn't really explain the value at all (though it does say you should change it from 330K to 390K depending on whether you're using 50 or 60 Hz)...
I remember my grandma house when I was a kid all you had to do is touch the lamp and it was on not good if you have animals they leave the lights on lol 🤔 👍👌✌️⚒️🔧
Lol I get data shits sometimes too
Thanks Clive 👍🇮🇪💚🙏🏼
That 68k resistor surely looked like 8k8 instead - the orange looks red to me :-)
What could possibly go wrong. Heck I've taken the arc flash of 60,000 - 20,000 volts through my fingers and out my pants just below the waist and into the fender. It like having a lead pencil.✌️♥️👍
Would have been cool to see the waveforms to see how far off full intensity it actually is.
Would be even better for lamp life if it switched on during the sine wave zero crossing point and then off during the rising voltage peak.