What 12v power supply for these Nine 3w LED lights?

Tempest

Member
First a little history:
In the kitchen we had Nine 12v 20w downlights powered by two small mains transformers with 12v outputs
One transformer powered five of them, the other 4 of them.

A few years ago, (with a bit of fiddling) I was able to remove the actual 12v 20w bulbs and replace them with these LED replacements:

Amazon product
All seemed fine at 1st but had some LED flickering keep appearing at times, may be some incompatibility or just age as the transformers are about 20 years old albeit as they are only secondary lighting they got used very very rarely.

Anyway. I need to replace the transformers I feel, and perhaps as I'm driving Nine 3w LED's now (27w total) as opposed to Nine 20w halogens (180w total) just one replacement transformer will do the job.

Now, I see online there are things called constant voltage drivers:

And talk about what type of 12v Transformer should be used on the lights (Amazon link above) I should select.

Advice most welcome as I don't wish to buy the wrong type, meant for 12v halogen as opposed to my 12v LED lights.
Thanks :)
 

IronGiant

Moderator
Just buy an LED rated transformer :D
 

Tempest

Member
Just buy an LED rated transformer :D

The more I read about each product the more confused I get.
One which looks fine, in the Q&A it says it's only tested for 1 item per transformer, so again confused if this means it will power 5 LED's if they fall within it's rated output.
And number of LEDS drivers per circuit.....

Perhaps I'm looking at wrong ones :(

Maybe this is better than Screwfix's offerings?
Amazon product
 

noiseboy72

Distinguished Member
Traditional transformers will have a variable voltage depending upon the load applied. If just powering leds, the voltage will be much higher and this can cause premature failure.

You can drive multiple leds from 1 power supply - or constant voltage transformer, but you cannot exceed the rated output of power supply. The one you linked to is not powerful enough, but you will ones that are. A 30w unit will be perfect.
 

Tempest

Member
Thanks.
I just placed an order for the larger version of the one I linked to.
Not the 24w one, but the 60w one.

As I'm powering 9 LED lamps at 3w each = 27w total, the 60w version I'm guessing will be pretty relaxed at powering just under half it's max.
 

neilball

Well-known Member
I’m a bit late if you’ve already bought something, but for 12v led lamps that are designed as replacements for filament lamps, and can run on AC then I use these...

I’ve used them with single LED lamps as low as 1.5w without problems, and also with dimmable 12v LEDs too (G9, MR11 & MR16).

If my LEDs are 12v DC then I use an appropriate DC driver selected for the load and characteristics of the lamp or strip it will be used with.
 

Tempest

Member
Thanks.
I don't feel it's being made very clear to the general public, and I was just the same.

You have, let's say a load of 12v downlights in your home, could be of a few different styles/types, and they were running say 20w halogens.

So go shopping and see the new LED's which are 12v and "designed to replace your old halogens" and they say something like "3w equivalent to 20w"

So Mr/Mrs/Ms/Gender-Fluid buys them, goes home, swaps them over, and job done.

The concept of, Is this actually the correct 12v Transformer never enters their head and the packaging just states it's a simple lower power replacement.
 

neilball

Well-known Member
Thanks.
I don't feel it's being made very clear to the general public, and I was just the same.

You have, let's say a load of 12v downlights in your home, could be of a few different styles/types, and they were running say 20w halogens.

So go shopping and see the new LED's which are 12v and "designed to replace your old halogens" and they say something like "3w equivalent to 20w"

So Mr/Mrs/Ms/Gender-Fluid buys them, goes home, swaps them over, and job done.

The concept of, Is this actually the correct 12v Transformer never enters their head and the packaging just states it's a simple lower power replacement.

It’s often easier for someone with electrical competency to remove the existing transformer and lamp holder, and replace with a GU10 lamp holder and therefore avoid the need for a transformer/driver providing the fitting is suitable for modification (and in terms of location and earthing arrangements) avoiding the need for a transformer at all.
 

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