today we're looking at dimming LED lamps
some people still call them led bulbs as if they grow out of the ground okay yes so what we've got
to set up here is our four halogen lamps and our legacy dimmer and that's probably what's in our
installation and then at some point we're gonna have to swap those out for leds yeah so we thought
we'd make this video to update the viewers on the various choices you have because lamp technology
has moved on enormously in terms of retrofit led lamps and so has the dimmer technology as well and
there's lots of videos out there but they don't necessarily reflect the true state of affairs that
we have with led lamps and actually in some ways how easy it can be so stay tuned for that we have
got some technical bits we have got the scope on the desk we don't want to scare you back to your
school science lesson but gary let's have a look at what people may have installed today halogen
lamps that we're going to try and replicate so let's look at their performance so if i bring in
the camera here and bring it up to full brightness talk us through first of all what's happening on
the scope and then we'll alter the brightness of the lamps as well through the dimmer okay so on
the scope we can see our ac waveform that's going into the lamps now you'll hear a lot referred to
as leading edge dimmer okay and that's probably the legacy dimmer that you may have fitted in your
installation i believe there still are some on the market for new installs and trailing edge is
the other alternative but these leading edge ones what will happen is that as the lamps are dimmed
the leading edge of the waveform is actually truncated to reduce the voltages going into
the lamps so you can see the further that the lamp is dimmed the more of the waveform is chopped away
and that gives us that nice smooth dimming with a halogen lamp okay and we're all the way down there
to its uh least bright setting okay let's pull it back up again so there we were on our waveform and
we can see it in faster motion chopping the front part of that waveform off as a leading edge dimmer
okay so these lamps now start to expire over time they're very difficult to replace we want to make
a choice to go to led so what we'll do next Gordon if we swap these out and put our led lamps in
and repeat the process again okay so if you just switch the dimmer twist them out luckily they're
not too hot otherwise i now have burned fingers and i'll put these lamps in that we got from
V-TAC right so they're all going to be the same and we're going to apply the legacy dimmer so it might
be what you've done at home isn't it you know the lamps have gone out you've popped down to your
local uh hardware store and you've replaced them now with the ones that you've chosen off the shelf
you've probably not spent a lot of time looking at the lamp but hopefully looking at our previous
videos you've looked for one that is dimmable so you look for that symbol to suggest that dimmable
yeah so these are dimmable lamps good good news and yeah so hopefully we're expecting them to dim
what a lot of manufacturers do is publish a whole chart of which dimmers they're compatible with but
probably most people wouldn't do that when they're stood in front of them at the shop or on a website
to go and check first because you may not know what the dimmer on the wall is absolutely in the
first place so we've just gone ahead put on our legacy dimmer so we've gone and gary power us up
right okay so if we go up we come so we'll bring the other camera back in so i'm on full brightness
there exactly the same waveform it's chopping the front path you agreed it is yes so same waveform
okay so i'm going to start bringing it down so here we go so let's bring the brightness down
so you can see again that waveform being been on the leading edge being cut away
right that's it i'm not carrying on going no no i i can't go any further that's it i've stopped
at that point there okay that didn't seem a lot of change from maximum brightness to
the low end okay so that is the first problem uh with sometimes with dimming led lamps that
because of our legacy dimmer there's only so low you can go with the lamps and
personally, if that was in my house I probably wouldn't be happy with that it's nowhere near
the performance I had with the halogen lamp well no, it isn't it's absolutely nowhere near the
performance so if i just bring that up back up quickly and then back down that's it that's it
that's as much as you've got and i've not dimmed to the point of where we're going off either yeah
now straight away if someone's gonna go rule well i need to change the dimmer and in the past that
may have been true but what i'm gonna do now gary i'm gonna swap that for a different set of lamps
from a different manufacturer and see what happens right okay so i'm gonna pop these ones back out
so these are dimmable led from a different manufacturer and you think these will have a
better performance with our legacy dimmer yeah so these ones are from LEDvance they're still branded
as Osram lamps there's a bit of history there but we'll not go into that now okay so these are Osram
ones then and we're to do exactly the same again it's going to chop the waveform in exactly the
same form so let's bring that one back in let's put them on to full brightness okay so we see the
oscilloscopes doing exactly the same as it was before and i'll just bring down the brightness
i've got a lot more control there yeah so with that lamp you can actually dim to off with our
legacy dimmer that is really good let's judge a little bit quicker yeah all the way that's got
a very good range so from the uh installer's point of view and the customer's point of view I've kept
my legacy dimmer i have replaced my halogen ones i've got the nice energy saving benefits of using
led but i've also got the performance now that my halogen ones had before as well gordon yeah so
now obviously we corrected that just by changing the lamps but let's revisit those lamps we've
just had with a different dimmer combination so we've brought back in our v-tac lamps let's
just remind ourselves how low we can go with those so if we're back here at full brightness
our legacy dimmer only can bring it down to their gordon how are we going to solve that problem okay
so we're going to swap over to a different dimmer and a different dimming technology so if i um
and so we're going to move over to a trailing edge dimmer and again
the name gives the gives it away that the waveform is going to be chopped on the
falling edge of the ac waveform right okay and that may affect the performance of these lamps
one that might be a benefit then well so i'm on a knightsbridge dimmer now so let's bring it over
so we've got our that's at full brightness and i'm gonna just bring this down yeah so we will
see that the waveform has now been chopped on the falling edge or the trailing edge of the
ac waveform and you've got you're dimming down you're dimming down you've gone all the way off
okay so i'll do that last little bit a little bit slower so i'll bring it back up
and then i'll just go really slowly now on that very final part of the dimming process
and there we're going to dim too often to off which is a significant improvement
a little bit of technical there going off if you want to bring in some terms to look good in front
of the customer you'd refer to that as the dimming curve right and so these lamps you can see from
that actually a lot of the dimming occurs in that final bit of the ac waveform as opposed to when we
had our earlier lamps the dimming occurred at the higher end of the ac waveform and it just
proves that those lamps when we had them with a legacy dim didn't work very well but it wasn't
necessarily a failing of the lamps themselves it was the fact that this time we needed to improve
the dimmer we chose the knightsbridge one and we got a lot better low end didn't we got it all the
way to dim to off we wouldn't do it before yeah we're certain and we're going to look at that
low end performance a little bit more detail in another video so watch out for that it might be
in the eye above my head depending on where you're watching um but before we move on gary let's just
mix things up a little bit let's put a range of different manufacturers lamps on the same dinner
so we changed the lamps over gordon against our dimmer which lamps are we using now okay so i've
brought back in the osram lamp supply by lead vans introduced one from philips i want from aurora and
the v-tac lamp we saw earlier and they're connected to the hamilton light stat dimmer
and we'd expect them all to perform exactly the same you're agreed bring the bring the dimmer cam
in let's have a look at the full power so i'm now going to slowly wind down the dim levels of those
you lamps already see they're going they're going oh we've just lost the the osram lamp closely
followed by the phillips and the other two lamps have gone to a minimum level so they didn't all
perform exactly the same did they go no and that touches on something i mentioned earlier about
this dimming curve and clearly different lamps are set up in different ways you know the the
osram lamp lose a lot of its output at the higher part of the waveform the philips had suggested
the mid-range of the ac waveform and then these other two lamps need a lot of the output goes
at the bottom end of the ac waveform and that's uh clear when installing the lamps in the first place
to choose exactly the same lamp freeze you fit in some people are probably thinking well that's
pretty obvious guys but over time some of those lamps might fail and what's the tendency then
to happen yeah well you just grab a replacement and put it in and then suddenly yeah you've got
different lamps at different light levels when the when the dimmer's being altered yeah no not
a good situation not one a good situation at all so that's probably a top tip in it so when
you're installing your lamps make sure when you replace them they're exactly the same lamp as you
had before otherwise these dimming characteristics can be different however another top tip is that
if you have a legacy dimmer and you choose the appropriate dimmable led lamp you can get them
to work perfectly can't you gordon you can and then obviously by introducing a different dimmer
you can improve that performance of almost any lamp and that's something we're going to look at
in the next video is that choosing an led dimmer and then seeing how you can do an additional setup
on the dimmers themselves to improve performance and particularly what we saw there in that low
end you know it's a personal choice isn't it whether you want the dim completely to off yeah
and possibly run the risk of plunging your guests into complete darkness when someone's messing with
a dimmer or park your lamp at a stable low end level and that is something we're going to look at
we're always interested in your opinions what's your go-to lamp what's your go-to dimmer what's
your experience of dimming led lamps any top tips that you want to share with us at
efix please leave those comments below and we'll try and get back to as many as we can