Electronically controlled LED lamps glowing when off.
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- Опубликовано: 19 май 2016
- LED lamps (and some fluorescent ones) may glow or flash when they're supposed to be off when used with electronic switching devices like solid state relays and dimmers. Here's why.
The main reason is usually the snubber network across a triac. This is usually a resistor and capacitor connected in series and appllied across the main terminals of the triac to attenuate sudden high speed glitches and transients that could result in the triac turning on when it wasn't supposed to. Triacs have a characteristic called DV/DT Where the D stands for delta, meaning "change in" so the characteristic relates to change in voltage / change in time. This relates to the triacs ability to turn off or remain off when a rapidly rising waveform is applied across it, like a pulse or transient. Typical values for a snubber network are 100 ohms and 100nF. Normally with a heavy load the capacitive coupling through the snubber network is not an issue as it gets shunted by the load. But with very low loads like LED lamps or small motors it may cause a situation where a lamp keeps glowing dimly or a small effects motor keeps running or shuddering slightly.
In some cases you can solve the problem by using another snubber network across the load as it then forms a divider with the one across the triac, and that can lower the leakage voltage to a level that the affected loads will not light or move.
A common approach to solving this issue in the theatre industry is to use a ghost load where a traditional lamp is used to load down a dimmer circuit controlling a small effect, and also help ensure the channel turns on properly, as triacs need a minimum holding current to remain latched.
If you enjoy this channel you can help support it with a dollar for coffee, cookies and random technical stuff at / bigclive 
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I don't understand electronics at all, but i find myself coming back to watch more. Maybe it's the soothing voice and gentle accent, but i've spent hours watching these videos
+Plum Bit Your comment is tripping me out. I was honestly about to write the exact same thing in the comments.
Snootches Bootches Maybe we find it therapeutic ha
+Plum Bit I believe so. Ill probably come out of this with some knowledge of the organs of electronics as well , which is great.
+Plum Bit I know nothing about electronics and next-to-nothing about electrical engineering. However, after having seen several of Clive's videos, I've started to become less and less confused when he traces circuit diagrams. I've started to learn to expect where _bridge rectifiers_ or _smoothing capacitors_ are going to show up. Microcontrollers still throw me, though. To say nothing of TRIACs.
Yes he has a smoothing voice and he does not cut a lot out of his videos, this I do like, I hate it when there is so much cut out you have to try to put together what they have done. Clive has a way of getting it over what he is talking about and the schematics with explanation is very good way of doing it.
If you watch enough of his videos you will start to pick things up, even if you have never worked with electronics. I like it when he moves on to do simple circuits other than lamps. Maybe he will explain what a Diode, Resistor, capacitor, Electrolytic capacitor does, though I think he did this in an earlier video
7:40
>capacitor (draws resistor) and resistor (draws capacitor)
Well played sir.
Juan Herrero lol
oh well, at least it is a linear system :)
Juan Herrero - i was going to say something about that tho Still Learning,; But See - I Am Learning from Clive!!
Can I suggest a video where you experiment with a couple of solutions to this problem? I know you suggested some things to try but it would be neat to see them in action and I think it would get a bunch of views.
I've got to thank you Clive, I put in a ceiling fan recently and the LED bulb would always stay on at a low level after switching it off and I thought it was a fault with the fan. I swapped the bulb for a halogen one (seems they don't sell incandescent bulbs anymore) and it works perfectly. This video saved me the effort of taking the whole thing out and replacing it for no reason so thank you!
Thanks for the warning about SS relays leaking enough juice to bite.
Clive it would be really great if you could do a follow up where you test potential methods of fixing the issue, since it is so common now with household dimmers and LED lamps. Would be interested to see for each potential fix -- snubber network, just a high value resistor, etc. -- the current draw when "off", the waste heat generated, etc. Thank you!
One of those quack power saving devices (PFC capacitor) connected in parallel with the lamp would probably stop the flickering/glowing, without taking much power. Hey, they may actually be useful!
Cool, a channel worth watching!, thanks man!
Loving those dulcet Scottish tones and the information and ideas you provide in your vids, keep it up, you got me interested in electronics again!
Regards and greetings from south east UK! :)
I'm so glad you put this up. It explains why some of the LED lights I put into my truck interior lights never completely go off.. couldn't use them. Can't figure a way to fix it even with your helpful suggestion.. Take Care
I come here for electronics, not art class. You can draw shitty schematics all day, as long as you explain what they do :)
:)
+bami2 Lurid...love that.
I laughed out loud when he talked about the drawing being let's say off standard.
WOW, Thanks ! I just spent 2 hours trying to figure out why my SSR was showing "almost" full voltage across the Output side, when NO input was present.....
I thought I wired it wrong...and you showed me what I had an assumption about - SSR are NOT "Old Fashioned" coil relays that make a NICE noise when opening and closing!
I had a CFL in my bedroom, standard UK house wiring, no relay, no dimmer, and it would flash about once every 5 minutes when switched off. Thanks for explaining why it was happening! 👍
Thank you Clive, this has been very very helpful. I have three DMX controlled power junction boxes. Each box has four three-pin-plugs. The boxes, and each plug therein is controlled by a separate DMX controller, which consists of twelve on/off buttons, (so I can run a maximum four boxes of four plugs each.). I've been using them to run a number of LED lights such as Chauvet Swarms, Mini Kinta, Mushroom, spots, and a number of others, for dances and parties. I have never been able to figure out why many of them keep flashing when they were meant to be off, yet work fine when turned on. I had to revert to using normal electric multi plug junction boxes and switching them on manually. I just tried experimenting with a double adaptor, with one outlet going to an LED light and the other to a standard 60W lamp. There was no flashing with both plugged in, but when I unplugged the lamp, the LED started to flash. Once again, thank you. Now I've got to figure out a way of putting a load on to each plug that's the equivalent of a 40~60 watt bulb.
I've been hooked on your videos for the past month now and I don't know why....maybe its your intense knowledge on electronics or maybe it's your interesting accent. either way, i don't plan on stopping watching your videos!!
I have that glow problem with my X10 controlled wall switch controlling 5 kitchen spots. Initially I installed fluorescent and now Led bulbs. Intuitively I installed one incandescent with the fluorescents and continued when I swapped them for the LEDs. Both types needed the incandescent. Now I know why the problem occurred. Thanks for the enlightenment.
That was interesting, thanks! I think with the continuous spread of LED lamps, we will have to adapt our electronics to them, so change the whole design of dimmers/solid state relays and so on. It's often like that when you change one part without changing the others.
I think the last solution was probably the best. include a higher power rated bulb or device in the sequence with a higher power requirement to shunt the leakage to a device that acts as a threshold to the system. Good video.
Thanks for your experience and clarification, most low cost SSR and dimmers will display same quirks. I wanted to energize a PWM fan array using the USB voltage to activate the solid state relay. Big failure, fans would just keep running at fractional speed with the relay control voltage removed. Two solutions found: Livolo active phantom load, or a PTC implementation.
you answered a long time question! I have and have used for years x10 dimmer modules for remote control and computer timers. now with regular light bulbs nothing but with CFL or led they all flicker. now it scared the £@#$ out of me at 3 am. but I am so used to it now I have a night light! thanks.
Found this out recently when I was using a solid state relay to control a neon transformer. Even when it was supposedly off, there was enough current going through the transformer to produce very tiny sparks when the output wires were a fraction of a millimetre apart. Luckily it didn't catch me by surprise, because I was also using the Cliff QuickTest and its neon indicator was also well lit even when the SSR was supposedly off!
thanks for giving me info on the! I bought a 100 pack of the clear wago connectors. these look awesome!! thanks guys.
Possible solution: Put an X2 capacitator in parallel with the lamp as a bypass for the leaking current.
NOT for dimmed lamps! Phase cutting produces harmonics. These higher frequencies will lead to dangerously high currents throug the capacitator when the lamp ist powered on.
If a dimmed LED lamp glows or flickers when turned off, use a "Kompensator 6596" from Busch-Jaeger. This is just a PTC in a casing. Bypassing leaking current to neutral, it will get hot an highliy resistive when the lamp is switched on.
Our old house had a light fitting in our bedroom that had a small leakage current. I remember walking up one night to the CFL bulb in the fitting flashing. It wasn't constant flashing, just a really bright flash every few minutes, then a few quick flashes every so often.
It was a bit freaky until I figured out what was going on. It was a bit like those stupid ghost hunting TV shows :-)
My patio has a pair of remote control track light fixtures, each with 3 lamps. I replaced all with cheap LED bulbs, and they'd come on okay, but when off would strobe weakly. I replaced them with even cheaper but dimmable LED bulbs, and they work perfectly.
I love these videos, I feel smarter every time I watch them.
Thank you for making me feel smart!
Hey Clive, big up from Finland!
Adding a plug-in transformer in parallel to the lamp (via a 1 to 3 outlet tap) seems to fix the issue without hooking anything up to the transformer output. A common old+heavy 5-12v DC "wallwort" is best; experiment to find the least vampiric one for your setup. They fix LED bulb issues with SSRs, dusk-to-dawn sensors, motion detectors, lit switches, etc.
is the worktop youre using just a generic shelf/worktop combo thing with interlocking legs etc ? the top of it looks like that boards that u put on top of them things
If your going for the one tungsten lamp as shunt for LED circuit concept, you can actually buy decorative large filament lamps. While technically these are much less efficient, they are not designed to light a room, so total current draw is often less, and they have a basically unlimited service life, which is cool given if it does fail, all your LED's will go back to either flashing randomly or glowing when ever the lights are turned off.
For tungsten lamps it is possible to use two 15W bulbs in series as a resistive load so the power usage is not that high and it takes decades for the bulbs to go eol.
We had this happening with a normal light switch, but it would flash every ~10 minutes. I am guessing it was the ac coupling in the lightswitch and the cabeling (capacitive effects) that caused this. amazing how little power these lamps actually need to give out light!
Hi Clive, is it possible to eased the flickering when switch OFF if i replace the capacitor with the same value?
Big Clive, I just bought one of these solid state relays to control a 1/2 hp electric motor. Any issues in that application?
Great video thanks Clive
I guess you could just put a capacitor between live and nautral to fix this and save 30kW while you're at it.
Very Interesting. I recently got some LED GU10 lamps for my room and noticed that when I dim them down they start flashing madly (faster the lower I go). But when I have a standard GU10 lamp in at the same time (non LED) the LED does not begin flickering until I turn the dimmer down far more.
I also noticed that when I had two LED lamps in, after a while both the dimmer and the lamps themselves began buzzing. However after removing one it ceased. What are you thoughts on the cause of that? (This buzz only occured on sockets with a dimmer)
Good video. Thanks for the detailed explanation. This reminds me of when using a CFL light and with a LED light plugged into to a socket wired to a old use Dimmer replaced wall switch, the CFL and LED lamps would flash even if the dimmer push-to-be-off was engaged. So irritating at night, the dimmer had to be replaced with the normal on/off switch. - I wonder if a pull-down to ground resistor (of some high value to not load down normal operation) between the 'snubber' capacitor and resistor would prevent the cap from charging and discharging in cycles. Yeah, its not worth the bother to modify the Solid State Relay but still in principle, I wonder if that would solve the issue.
There is always a leakage voltage on an SSR .It will allow low voltage low current devices to to stay illuminated .We will switch heater elements through and use a manual motor starter or contractor to disconnect the output going to heaters .Especially at 600V 3 phase heater banks used in commercial ovens .Croydom, Opto,or Carlo Gavazzi they all have the same issues
Clive, could you please make a video about driving triacs for use as switches and dimmers, and what typical practical circuits look like?
Huge undimmed fan of your videos!
I've had the same pulsing flashes with compact fluorecant bulbs when they have an illuminated switch in the circuit, when the switch is in the off position.
had that problem on a CFL, after it was one for a while. every few minutes it flashed very slightly. annoying when youre laying in bed and see this trough your peripheral vision...
I'm going to be making my own laundry detergent injection system, do you recommend 12vdc or 24vdc?
Here in Norway we mostly use 2, or 3-fase 230v, and in certain conditions on single pole lights switches theese LED fixtures will continue to glow dim even when off. Only explanation I could find was capacitive leakage through ground... At night the LED lights are bright enough to navigate in "complete" darkness.
I have this problem with cheap LED's I bought on Ebay, they were $1 each in boxes in 10 a few years ago, they work fine, but glow while off, Name brand LED globes bought locally (phillips etc... 5-6 bucks each) Do not do it, Do they have extra circuitry to avoid the problem? or do they just use enough power (6watts instead of 3 like the ebay globes) that they don't glow from the leakage?
Love the Wago connectors but prefer the 221s, smaller and easier to use.
PS: Thanks for your posted videos.
I have a coil fluorescent bulb in a fitting controlled with an everyday light switch.
It flickers slightly when off.
I don't think there is a solid state relay involved anywhere in this circuit. Where would be the leakage? could it be the a live wire laying in parallel with the cabling in the roof?
So it's the snubber network that makes my GU10 LED lamps have a soft close on my dimmer for electronic transformer?
If that's a knock-off of a Fotek, would that make it a Fauxtek?
i realize I'm quite randomly asking but does anyone know of a good place to stream newly released tv shows online?
Interesting stuff. Thanks for the explanation. :)
Clive could you do one of your great videos on building the snubber network to stop the flickering on the LED light and test it. Thanks
So i have what may be a doggy question. Is it possible to wire a PTC into the light circuit and have it create a load? I have a friend with a large number of recessed ceiling lights in his house ( 45 ) on 4 different 3 way digital dimmers and he wants to convert to LED but unless he leaves one incandescent in each circuit the whole lot all glow when there off. So my half brain idea was to install a 5 watt 80C 110v PTC heater, one on each circuit mounted to a heat sink inside the cans plugged into the circuit to create a slight dummy load. What do you think.....they generate less heat then the 150w max rating that the metal can it rated for was my thought...
I have noticed that glowing effect in a couple of led lights hooked up to a dimmer in my house, and thought it was the lights having the problem. Now I know it's the dimmer's snubber network causing the issue :P
Two way switching gives a similar effect here in UK, flickering/dim LED's.
I have a question. Is the bayonet type connectors more dangerous than the screw type?
this answer some of my questions but not all of them. I have a chandelier with a dimmer I recently converted it to LED. I bought a new dimmer I installed it the way the instructions said to install it if you don't have a ground wire I installed dimmable LEDs but now everytime I turn it on it blinks you have to start it out at the dimist level then power it up to full or it just blinks. I'm starting to understand why it blinks but what I need to know is how to stop it.
Home made SS relays with quadracs ("snubberless triacs") for the win! Relay or dimmer applications won't ever notice the missing quadrant, and the leakage is essentially zero.
Got a link to a schematic for that?
@@tcurdt Yeah I drew one. It is a very basic but functional SSR, not a dimmer. Lets see if RUclips lets me post the link:
eeberfest.net/etc/SSR.jpg
eeberfest.net/etc/SSR.pdf
Note that the triac MUST be "snubberless"!!
Also if you are using 240VAC you should probably change the 360 ohm resistors to 750 ohm. I've only ever used the circuit (as drawn) on 120V.
@@tcurdt Additional thought for you: if you wanted to fire the SSR using a GPIO pin on a 5V microcontroller (e.g. Arduino UNO) it would be best to substitute a MOC3063 for the MOC3061 shown and use a 470 ohm resistor in the control circuit. Done like this the SSR can be turned on with 5V ~7mA, well within limits of GPIO. As drawn with the MOC3061 and 120 ohm resistor it needs more like 30mA to turn on.
I had set up a light system onto my car some time ago, and one circuit of it, (being two circuits in the system, controlled by the strobe controller) would sometimes just give a dull glow. Not always, I noticed, but sometimes, it would just barely glow one of the control lights. I'm guessing this is why? It's interesting, to say the least, but I thought something was horribly broken.
In the off state I'm still getting like 80v (120v connection). Any ideas how to remedy? I'm supplying 5v to the input side.
iv had two home bargains eco lamps fail very quickly clive, one smells of magic smoke, one was a colour changer, the non color changer has cracked the white coating like fault lines on a volcanic surface and the other seems to have oozed brown from the ir led, thoughts?
How can I make a dimmer? I have a cheap little desktop fan with just an on-off rocker switch but it's too strong and noisy! I'd like to be able to adjust it!
I tried putting a 47K 1/2 Watt resistor across the Live and Neutral wires, going to a 240V led bulb.
After a few minutes the resistor got to around 48 centigrade, and was too hot to touch.
The resistor did not breakdown, even when I extended the on time to 30 minutes.
The resistor stopped the led glowing when the relay was off.
I also tried connecting a wall wart type power supply across the Live and Neutral going to the 240V led bulb. That also took care of the led glow.
So, am I wasting energy, using these SSRS and curing the problem with 'heaters'?
Looks like it is more sensible to use mechanical relays for these problem 240V led applications.
How about placing a Zener diode in series with the snubber network?
So in what scenario would you use an SSR? Are they build into home lighting circuitry? Clive mentioned set lighting...
+Lightning Graphics He is kind of like Kramer from Seinfeld, remember when he bought home that TV set, couch and all?
Besides clive is tall like Kramer, has a wild beard, and dances skittishly when jolted with the live mains. :)
Back in 2008 I fitted the then 1.3w GU10 LED bulbs now here is the puzzle for you. I also was able to see the slight glow on these LED Bulbs the switch was a standard light switch, GU10 has no earth point I never Figured a valid reason of how the LEDs were doing this.
I checked that the switched wire was live the bulb only connected to neutral with old-fashioned 5A wire fuses at the fuse box disconnecting the live wire from the switch - no change standard 1.5mm flat lighting cable white with red and black conductor wires
My only thought was the some kind of eddy current /transformer effect from the steel wall conduit (1950s house that been re-wired using the old conduit that once had the rubber flat cable in)
Helpful drawing ever
I have some CFLs which I fitted in my garden and one of them flashes when off - not always the same one, and not as quickly as the Asda light in the video. But I know why they do this - the outdoor switch that I wired them to has a neon indicator across the switch that comes on when the switch is off, leaking some current to the CFLs. The neon in turn only lights because of the load through the CFLs.
Thank you for the detailed explanation! I was starting to belive that there are ghosts in my computers LEDs 0.o
Good explanation sir :)
what about having a master off switch before the dimmer to stop all eletrical flow when not wanted.
Ever thought of getting one of those Self-Balancing board/Swegway/Hoverboard thingys and dissect them? Maybe get a cheap broken one on Ebay?
does the seccond snubber network need to be of a spesific value? (can i use 100R100nf?) it drives me nuts that i have to connect a load (usualy first ting on hand is a par) that gets anoyingly hot, when the load your intersted in is so small
i want to build a few "snubber plugs" instead of a conventional load :) (perhaps i need to build a fiew versions and pick the best one when neaded :P )
kind regards,
Milan Hofman
100 ohm and 100n would be a good starting point. Also include a high value resistor across the capacitor to discharge it. 1 Megohm should be fine. For an actual theatre dimmer you may need a low resistive load to make the circuitry stable. A traditional 60W lamp in a work light like a clip-on metal caged hand lamp is one option. A coloured lamp (even a UV style tungsten lamp) will also avoid light spill.
same thing happens with the dimming style car interior lights. I figured that it was only noticeable because LED take mich less current filament lamps.
Link to the bulbs that light up from the neutral when turned off???
This reminds me of a flashing joule thief. You add resistance between the battery positive and the coil tap. Add an electrolytic filter capacitor from the resistor/coil tap to ground.
ghost load? never heard any one say that. Ive heard Phantom load. you learn something new everyday
great video! but im completely new to this and would like to have a step by step how to install the snubber network? thanks.
What about dimmable leds? They should work fine, right?
Help. I have started using Smart bulbs in my flat. Living room are fibe. Bedroom one has a double switch (independent switches in 2 locations which turn the power on/off). I had to use a GU10 to E27 adapter. Obviously the power is on, but when I turn it off (via smart app) it very faintly flickers.
Any ideas? They switches are not dimmer. I hear it might be to do with the load or poor connection at the bulb. Should I replace the pendant to a E27 and do away with the adapter?
It's common for some LED lamps to glow slightly on two way switching due to increased capacitance in the switch wiring. Try a different brand of lamp.
I have the same problem with some aliexpress lights, the power supply, when switched off in either live or neutral, can still turn the led slightly on, when the led board has something near, like my hand. I guess it acts like some sort of capacitor, and allows a tiny current to flow, just like thoose screwdrivers that can tell you if the wire has voltage, even without touching it... With thoose ones, i have to use a double switch to cut both live and neutral...
For my elderly mother I wired in a motion sensing switch (built in the wall to replace a normal toggle wall switch, you understand?) and it did this when not triggered on. Let me be clear -- it did this with an incandescent load ...Would this happen for the same reason?
Of course with the Incandescent bulb you did not see a flicker, it just constantly glowed when you wanted to sleep. (it had an adjustable timer for the ON time and a pot for the light and adjusting neither helped.) I thought I was saving money & liked your like playing about with lights & being ahead of the times but in the end it just cost $30 extra to begin with plus loads of my time. Plus I figured it must have leaked like 5-10 watts of power.
It was made by a well known lighting and switch maker, too, I forget the name (its pry in one of my electric tool boxes somewhere in the basement) I really want to buy another but it seems like a waste of money ... next time I will probably just try an automated home hub as I've noticed there are ones that do similar things.
But it was annoying as all get out. Makes me reluctanct to ever buy another one -- if I ever run across the thing I'll try to edit this to add the name because now its bothering me I can't remember that name.
can you measure the leakage current and/or wattage?
I have a timer for my outside light. Its one of those pole things with 3 LED lamps in it. It flickers from the leakage through the SSR. Mildly annoying, but I could stop it by screwing in a standard lamp if it bothered me enough.
+bigclivedotcom Have you tried to put an "energy saving" (just a big capacitor) between the live and neutral after the relay? it will act like a dropper and if the value is high enough, the ac voltage seen by the lamp will be negligeable when the relay is off and this will just change the power factor when on.
It's true... Every day is indeed a school day.... For many, many years, I always assumed that the leakage current was coming through the triac / SCR (Delete as applicable). I had no idea that it was actually the snubber network....
This happens in my house when I remove one of the two led bulbs from a circuit which is switched on a double switch with another light circuit. Only happens when the other light is lit, so I assumed there was some induction happening in the double switch. Happily, once both bulbs are in the leds don't flicker anymore.
the flashing is actually pretty cool for an outside lamp
I had an interesting issue when the switch was off (for led ceiling light) but the other switch on the same socket was on (for wall lights) the ceiling light would flash. if both were off then no issue.
turns out that voltage was being induced in the neutral (apparently) due to the adjacent circuits and bank charging the capacitor.
I had to get rid of the wall lights all together
Thanks for the great video - any down side to removing the snubber network from the triac?
+docpaul May cause issues with some loads, and in the SSR it is usually potted in resin.
Whats the difference in using a fly-back diode or the RC in series used as a snubber?
You can't use a flyback diode here. This is AC. There is no “back,” current is _supposed_ to flow both ways.
Interesting... way back , found there was enough leakage from the wire to wire capacitance in a 2 way stair light circuit to cause atrocious interference from a CFL when switched off - not enough power to light or flicker, but it wiped out AM radio.
Can you not have a relay or contactor before the solid state?
I wonder if the power draw in the "off state" does increase or decrease if you put an incandescent bulb or resistor in parallel to the LEDs? Naively, I would think that something in parallel could only increase the power draw by decreasing resistance. But if the incandescent bulb reduces the voltage, maybe the LED circuit isn't even able to really start using current? Does someone have experience with this?
love this stuff
I ran into the same thing when I installed one of those lighted "nightlight" style switches in my hallway to control a CFL. There was enough current coming through the light in the switch that every 1.2 seconds the CFL would flash ever so dimly. Took me 3 days to figure out what was going on.
+bigclivedotcom I got a good laugh out of the sudden deterioration in quality of your drawings :D
excellent video as usual :-)
bigclivedotcom I've had similar issues with LED bulbs in light fixtures that have "dusk to dawn" sensors in them. I've found that using dimmable LED's have solved the flashing or dimly lit issue. That is to say the dimmable LED's don't seem to have this issue.
Clive, have you been on the White/red wine like substance?!
Thank you
whats the difference in side an led bulb between a dimable and non dimable lamp