Replacement of MR16 transformers

[FullPint]

Hi,

In my bathroom I've got 6 MR16 fittings which I've just put LED lamps into, problem is couple of them flicker, presumably where the transformers aren't coping with the LEDs. Each fitting has it's own little transformer, so my question is can I cut off the old per-fitting transformers and replace them with a single central transformer like this one?
https://www.tlc-direct.co.uk/Products/LTYT50.html

I'd place the transformer centrally to keep the LV cable runs short - the longest would need to be about 1.5m.

It would be simple to do and I can't think of any reason it wouldn't work, but figured I should check with people who know more than me before going ahead!

Thanks for your time!

 

[Taylortwocities]

The LED lamps just do not have a big enough load for the old transformers and/or they are not compatible. You could change the transformers for LED drivers (one or more of them) but thats expensive.

The way to do it, is not to use transformers or drivers, but to change the lamps for 230v LEDs. Then there is no need to have an external voltage converter box.

 

[FullPint]

Thanks TTC,

You're right, if I was starting again I'd buy GU10 fittings and lamps, but I've bought the MR16 lamps now so was hoping to be able to use them. I figured a new single transformer for the 6 lamps at about £7.50 would be the most cost effective way, unless there is a reason why I shouldn't do it that way. What do you reckon?

Cheers!

 

[Taylortwocities]

Up to you. But you need a specific LED driver that is suitable for the LEDs you have bought.
One driver can do the lot, but you need to get the right size. Not sure if that TLC one is suitable.

 

[FullPint]

Thanks again,

It's a 0-50w transformer designed for LEDs, it'll be powering ~30w of lamps.

Transformer info is here (YT50LZ): https://www.varilight.co.uk/lighting/dimmable-transformers.php
Transformer datasheet: https://www.varilight.co.uk/leaflets/YTZ Series Transformers.pdf
Lamp info is here: https://www.screwfix.com/p/lap-gu5-...d=294407#product_additional_details_container

In fact the datasheet shows how to wire the transformer to multiple lamps so it all looks OK to me.

Cheers!

 

[Taylortwocities]

Do let us know how you get on!

 

[Iggifer]

It's a 0-50w transformer designed for LEDs, it'll be powering ~30w of lamps

But it also says on the varilight website

"Suitable for 12V a.c. LEDs up to a maximum of 25W"

 

[winston1]

But it also says on the varilight website

"Suitable for 12V a.c. LEDs up to a maximum of 25W"

it'll be powering ~30w of lamps. Need I say more?

 

[Iggifer]

it'll be powering ~30w of lamps. Need I say more?

That was my point

 

[ericmark]

The MR16 LED replacements I bought had 50 Hz plainly written on them. Although the electronic transformer is rated 0 - 50 watt it does not state the output frequency and likely it is in the MHz range, so it would be safer to get a toroidal transformer like this one where you are sure the output is 50 Hz.

You don't require a driver, a driver should be built into the MR16 package which controls the current to the LED's there are some incorrectly labelled drivers which regulate voltage rather than current, however there output is DC.

You can get both DC and AC MR16 packages, but the DC type tend to be much more expensive, they have better quality drivers built in and can often work on a voltage range of 10 to 30 volt, they are designed for caravans and boats where the battery voltage can vary, so the ones bought in Lidi and Screwfix are normally AC.

From Screwfix website

you can clearly see 12V 50 Hz written on the bulb, however nothing in the advert says 50 Hz you have to look at the picture. It may be they will work on DC, but why take a chance, may as well get a transformer with a 50 Hz output.

 

[bernardgreen]

may as well get a transformer with a 50 Hz output.

rememberong all the time that SMPS ( aka "electronic transformers" ) described as having an AC output maybe producing AC at a frequency much higher than 50 Hz.

As some 12 volt AC input LED drivers require the input freqency to be in the order of 50 Hz using an SMPS to supply 12 volt AC to LED drivers ( each lamp has a LED driver inside it ) can go very wrong.

 

[ban-all-sheds]

Should be easy enough to find out from the maker what the output of his product is, and which lamps he knows work with it.

 

[ericmark]

My point is I like many others thought the MR16 replacement LED units were DC, however I was clearly wrong, marked clearly on the lamps 50 Hz so a simple toroidal transformer is what they are designed for, not drivers, and not electronic transformers. These

rated 50 VA cost under £20 and are clearly matched to the lamps, so the only reason to use anything else is if you want to dim the lights, and since you were not suppose to dim quartz lamps which the LED lamps are replacing why would you want to dim the LED lamps.

 

[bernardgreen]

Should be easy enough to find out from the maker what the output of his product is

Tried that some time last year, The technical person at the importer / supplier had no idea of the frequency of the AC output. Neither could he obtain the information from the maker.

Using a scope the "AC output" was seen to be a rounded off square wave with a frequency in the kHz range. Frequency and mark-space ratio varied with load and the whole installation was un-stable.

 

[ban-all-sheds]

I would hope that with this make:

one would not have such problems.