Suppliers 12 volt LED advert and advice.

[JohnW2]

Well as I said with a halogen lamp on the SMPS the reading was as expected.

Yes, but that would have been with the current and voltage in the load roughly in-phase (i.e. PF ~1). What I was wondering was how well it copes with the situation when the current waveform is chopped and the PF of the load appreciably away from unity, since determination of true power may then be a bit more complicated. However, I don't know how the PF of the load will affect the PF presented to the 230V source.

Kind Regards, John

 

[winston1]

What I was wondering was how well it copes with the situation when the current waveform is chopped and the PF of the load appreciably away from unity, since determination of true power may then be a bit more complicated.

I don't know either. I was just commenting on what I observed.

 

[JohnW2]

I don't know either. I was just commenting on what I observed.

I realise and, and am not criticising. I was merely pointing out that one should probably be cautious in interpretating results from a cheap measuring device designed to measure the magnitude and phase of (usually relatively 'high') 50Hz sine-wave currents in situations in which the current is very small and in which the waveform (and frequency components) may be appreciably different from what the device was designed to measure.

If such a device were going to give inaccurate answers in some situations, one in which it was measuring the small current into an SMPSU which, in turn, was feeding a probably non-linear load would probably be high up the list!

Kind Regards, John

 

[ericmark]

I used a plug in power meter in the 240v side of the SMPS/transformer. I measured using MR5.3 LEDs and halogen on both a transformer and SMPS. With halogen the correct power figure was shown using both supplies. With LED the power approx doubled using. SMPS.

Now that is interesting, I have a plug in power meter, but don't have any electronic transformers to test, calling them electronic transformers as really only guessing they contain a SMPS or PWM and even then there is no need for a SMPS to work in the MHz range or to actually have a transformer inside.

This to my mind is a major problem, we are simply guessing what is likely inside them, the only information given with most is 30 - 105 VA 11.9 volt not seen any with 10 MHz marked on them, some it does give the output frequency on the data sheet, but we normally don't have the data sheet to hand.

I know my multi-meter has a frequency range, but although I can set a generator to 50 Hz, not sure what it would do with an output in MHz range, not even sure how it would work in the KHz range.

And in the main we are not looking at electricians swapping to LED, we are looking at the DIY guy who is unlikely to own a meter to measure frequency. Even with DC supplies we have no idea how smooth, I don't have an oscilloscope so no idea what output really looking at, we see with inverters the simulated sine wave, and with DC the RMS valve may be 12 volt, but what peak voltage is unknown. The old battery charger was rated 12 volt however peak is likely over 17 volt.

So nitty gritty is how does one advise a DIY guy who wants to change a quartz lamps to a LED lamp? I really don't know. Clearly a lamp marked 50/60 Hz will run fine with a toroidal transformer, and it will not work if the electronic transformer (I do hate that name) says 30 - 105 VA and the LED is less than 30 watt.

From what Winston1 tells us even if the electronic transformer is rated 0 - 105 VA it should still not be used. The power supply marked DC is also a problem, as no idea how smooth the DC is. If the supply is 36 volt to the regulator and the regulator has a mark/space ration or 1:3 then the average output is 12 volt, fed to a LED with a resistor driver built in that's OK, fed to a LED with a PWM driver built in then it may go pop.

So what do we tell people?

 

[JohnW2]

So nitty gritty is how does one advise a DIY guy who wants to change a quartz lamps to a LED lamp? I really don't know.

I suppose the simplest advice of all is to encourage people to stick with (or revert to) 230V/240V lighting! Then, certainly with conventional switching, any lamp/bulb designed for 230/240V DC will simply work, whether it be GLS, halogen, CFL, LED or anything else. If one wants dimming with anything other than incandescents, there might still be issues.

Maybe I'm missing something, but, other than in the relatively uncommon situation of one wanting/needing ELV lighting for 'safety' reasons, I'm not at all sure I understand what alleged advantages made ELV lighting become fairly fashionable! As I see it, introduction of an external 'voltage conversion' stage is bound to introduce losses, and also introduces something additional to go wrong!

The power supply marked DC is also a problem, as no idea how smooth the DC is. If the supply is 36 volt to the regulator and the regulator has a mark/space ration or 1:3 then the average output is 12 volt, fed to a LED with a resistor driver built in that's OK, fed to a LED with a PWM driver built in then it may go pop.

I may be wrong in some cases, but I think you'll find that power supplies from reputable manufacturers with a stated output of "12V DC" will usually have a fairly clean and reasonably well-smoothed ~12V output. It's those specified as "12V eff" one needs to be cautious about - since, as you say, they could have, say, 36V pulses with a 1:3 mark-space ratio, or anything else which averaged at 12V!

Kind Regards, John

 

[winston1]

and it will not work if the electronic transformer (I do hate that name)

Don't use it then. They are switch mode power supplies. Use SMPS.

Now that is interesting, I have a plug in power meter, but don't have any electronic transformers to test, calling them electronic transformers as really only guessing they contain a SMPS or PWM and even then there is no need for a SMPS to work in the MHz range or to actually have a transformer inside.

This to my mind is a major problem, we are simply guessing what is likely inside them, the only information given with most is 30 - 105 VA 11.9 volt not seen any with 10 MHz marked on them, some it does give the output frequency on the data sheet, but we normally don't have the data sheet to hand.

They generally run around 30kHz with an awful waveform the mark space ratio of which changes with the load or input voltage.

So nitty gritty is how does one advise a DIY guy who wants to change a quartz lamps to a LED lamp? I really don't know. Clearly a lamp marked 50/60 Hz will run fine with a toroidal transformer, and it will not work if the electronic transformer (I do hate that name) says 30 - 105 VA and the LED is less than 30 watt.

The best advise is to change to 240 volt LEDs.
The second best advice is to change the SMPS to a toroidal transformer.

 

[winston1]

I'm not at all sure I understand what alleged advantages made ELV lighting become fairly fashionable!

When they first appeared I only recall seeing ELV spots in the 50mm size. When mains voltage ones appeared the light was less white and the life of the lamps was about half that of ELV ones.

With LEDs neither of the above applies.

 

[ericmark]

With the quartz bulb the filament is thicker at 12 volt than at 230 volt so it takes longer for the thickness to vary enough for it to rupture, also the whole idea is to maintain a constant temperature too hot and it burns out, and too cold and the tungsten is deposited onto the quartz rather than back on the tungsten so the regulated output of a SMPS added even more life to the bulb as long as no one did anything daft like add a dimmer to it.

However although the spec gives a longer bulb life with 12 volt, when the filament ruptures it could cause ionisation within the quartz envelope which in turn could take out the SMPS and/or cause the quartz envelope to fail, this is the main reason that the MR16 has glass over the quartz to stop white hot bits of quartz falling from the unit. Also there was a UV problem which the glass also removed, I know the small 500W spot lights that were once so popular could not be used if the glass broke because of these dangers.

As said with LED neither the very careful voltage control or the low voltage is required, and with chandeliers the glass globes placed around the quartz bulb to retain the white hot bits and to stop the UV is no longer required, plus using a dimmer will not reduce bulb life, making them far better. Although the G4 bulb is available as 230 volt I question if the chandeliers used are wired to be able to safely run at 230 volt?

Also they do seem longer than the 12 volt versions, and since LED lamps are damaged by heat, it may be the protective globe used with quartz lamps must be left off, which will make the whole lamp look very different to when using quartz bulbs.

So I do question if 230 volt or toroidal transformer is best answer? I know we have had BA22d bulbs at 12, 24, 50, 110, and 230 volt, but in general the extra low and reduced low voltage versions were not available to the general public, but with a lamp designed to take 12 volt bulbs being converter to take 230 volt bulbs, I would say the risk that some one in the future will in error fit a 12 volt version is too great of a risk.

 

[ban-all-sheds]

I know the small 500W spot lights that were once so popular could not be used if the glass broke because of these dangers.

Could be worse. People changing the 15kW arc lamps in (proper) IMAX projectors have to wear body armour in case the lamp breaks - the gas inside is at 2.5Mpa

 

[JohnW2]

.... Although the G4 bulb is available as 230 volt I question if the chandeliers used are wired to be able to safely run at 230 volt? .... So I do question if 230 volt or toroidal transformer is best answer? I know we have had BA22d bulbs at 12, 24, 50, 110, and 230 volt, but in general the extra low and reduced low voltage versions were not available to the general public, but with a lamp designed to take 12 volt bulbs being converter to take 230 volt bulbs, I would say the risk that some one in the future will in error fit a 12 volt version is too great of a risk.

I was not suggesting that anyone should use a light fitting designed for 12V at 230V (i.e. 'converting').

I agree that it's unfortunate that the same bases are used for both 12V and 230V bulbs/lamps, but that seems to be a fact we're stuck with. In addition to those you mention (I certainly have some 12V BA22s for a car inspection lamp), one (including 'the general public') can certainly get GU10 and GU5.3 bulbs/lamps (and probably others) in both 12V and 230V.

In passing ...

...a lamp designed to take 12 volt bulbs...

... illustrates the potentia confusion of language that has been created. At least you were being sensible - I imagine that a good few around here would say that you should have written "...a lamp designed to take 12V lamps..."

Kind Regards, John

 

[ban-all-sheds]

I imagine that a good few around here would say that you should have written "...a lamp designed to take 12V lamps..."

Really?

There may be people who might themselves have written "A {light|luminaire} designed to take 12V lamps", but how many go around telling others to use terms like that?

 

[ericmark]

In passing ...
... illustrates the potentia confusion of language that has been created. At least you were being sensible - I imagine that a good few around here would say that you should have written "...a lamp designed to take 12V lamps..."

Kind Regards, John

We had lamps well before electric and historically the lamp fits on a spigot or other holder so it could be removed for lighting, I still have the bracket to fit on my push bike so I could slide the lamp on at night, Post office bikes had them front and rear but most bikes front only.

I only made the mistake once ordering a head lamp rather than a bulb, the whole head lamp arrived minus the bulb.

Yes I agree bulb refers to shape, they were bulbous, you could also get wicks and mantels for lamps, but electric wise you has tubes and bulbs which fit inside lamps. The way the lighting industry tends to retain old names for new items, maybe we should call them wicks or mantels?

The problem is more the way the Americans use different words, 12 volt is low voltage to them, not extra low voltage. And also 12 volt with motor vehicles is anywhere between 11.5 and 14.8 volt, days of dynamos up to 16 volt. OK BS7671 says 11 to 14 volt for supplies to caravans, but that does not allow for stage chargers.

But be it a head lamp, side lamp, tail lamp, brake lamp or reversing lamp, standard lamp, or table lamp, it has always referred to the whole thing.

 

[JohnW2]

We had lamps well before electric ... Yes I agree bulb refers to shape, they were bulbous, ... but electric wise you has tubes and bulbs which fit inside lamps.

Well, we used to .... now we apparently have lamps which 'fit inside' table lamps, standard lamps, inspection lamps, headlamps etc. etc.

I do suspect that, on this occasion, the inventors of this 'new correct terminology' are quite probably on a loser - even the youngest generations do not seem to have adopted it, any more than have most of the places where they would usually go to buy 'the bits that produce light'!

Kind Regards, John

 

[ericmark]

Next you will be saying you didn't write that, you will claim you texted it whatever that is?

I was sending a small message to my son, I expected his wife may have been reading it, so asked if he had QRM, he answered as expected QSL, however it seems she did not understand Q code, they use things like LOL what ever that means!

 

[JohnW2]

I was sending a small message to my son, I expected his wife may have been reading it, so asked if he had QRM, he answered as expected QSL, however it seems she did not understand Q code, they use things like LOL what ever that means!

In that case, you probably could have said things explicitly about his XYL and she would not have understood (although I can understand why some 'XYLs' are not too impressed with that terminology!)

Kind Regards, John