LED Driver

[securespark]

Planning to run a couple of 6.5W LED MR16's off one of these:

https://www.ledhut.co.uk/24-watt-led-transformer-driver.html

Tried to ring LEDHUT, advice is hopeless.

WRT losses or intereference, I was wondering how long the secondary lead could be on 0.75.

Was going for the 20W one, but this has no flying leads, which suits better.

Is there a minimum load too? some of these transformers will have just one 6.5w

Cheers guys!

 

[Iggifer]

For the sake of £1 get this driver instead. It's gonna be much better and Aurora's technical support is top notch.

How long do you need them to be? I think it will also depend how tolerant your LED lamps are. If they're happy with 11vdc you're gonna be able to have much longer leads than if they stop working at 11.7vdc

We just did a job with some constant current drivers that were marked max secondary leads 2m, we just had to make it 4mm² 'flying leads' for the 30-40m runs

 

[securespark]

Thanks, Igg.

Max 5m on one run and 2m on all the others.

 

[Iggifer]

Oh. Can't see that being an issue at all. If you can you could always up the 5m to 1mil but I don't think you'll need to

 

[bernardgreen]

We just did a job with some constant current drivers that were marked max secondary leads 2m

Very often the specification of a maximum cable length has nothing to do with voltage drop but is necessary to limit the amount of spurious radio frequency energy that is radiated by the leads to an acceptable level.

With a constant current driver the voltage drop along the leads from driver to LED is compensated for by the driver setting it's output to the voltage necessary to drive the required amount of current through the lamp

 

[winston1]

Why don't you use 240volt MR16 LED's? No driver required = less to go wrong, and less to worry about getting the wrong one.

 

[securespark]

Appreciate that but want SELV for safety reasons.

 

[JohnW2]

We just did a job with some constant current drivers that were marked max secondary leads 2m ...

I've mentioned this before ... although it's not uncommon to hear people talking about constant-current LED drivers, I wonder how easy is is to find LED bulbs/lamps (essentially just 'bare' LED elements) to be 'driven' by them? I'm not sure I've ever seen any (other than true 'LED elements') and suspect that they may well not be found in any normal retail outlets.

Kind Regards, John

 

[333rocky333]

As bernard says its more to do with interference on some units, most decent constant voltage drivers dont tend to state a limit IMO, if you think about it most are made to run an Led tape sometimes 10 metre long.
I have yet to see one with a minimum load rating,
we see them a lot, popular with signage and sometimes the leads are about 4 metres and then the internal tape another 3 metres.
Meanwell units seem popular

 

[JohnW2]

Why don't you use 240volt MR16 LED's? No driver required = less to go wrong, and less to worry about getting the wrong one.

I'm not so sure about "less to go wrong". Every single such LED lamp has to contain some sort of (often quite crude) AC LV -> (usually DC) ELV 'power supply' - which is appreciably more complex than the electronics required for current control in those designed to be fed from a (single for several lamps) external power supply.

Kind Regards, John

 

[Iggifer]

I've mentioned this before ... although it's not uncommon to hear people talking about constant-current LED drivers, I wonder how easy is is to find LED bulbs/lamps (essentially just 'bare' LED elements) to be 'driven' by them? I'm not sure I've ever seen any (other than true 'LED elements') and suspect that they may well not be found in any normal retail outlets.

Kind Regards, John

It wasn't a design decision to use CC drivers as opposed to CV but the fittings (flush low level wall lights) came with the drivers.

The fittings are essentially just a 5W LED chip mounted in a plastic frame - so much as you describe a 'bare LED element'. But you're right, not something we come across all that often.

Aurora have been known to supply CC drivers with some of their fittings. We don't use them a lot but I think it helps them with their warranty on bigger projects knowing that one driver is driving one fitting.

 

[JohnW2]

The fittings are essentially just a 5W LED chip mounted in a plastic frame - so much as you describe a 'bare LED element'. But you're right, not something we come across all that often.

Indeed - in fact, as I said, not something that I can recall having ever come across - which makes me surprised that we see so much mention of CC drivers in dicussions in a DIY forum!

Aurora have been known to supply CC drivers with some of their fittings. We don't use them a lot but I think it helps them with their warranty on bigger projects knowing that one driver is driving one fitting.

I would have thought that CC drivers come into their own if/when one wants to run a number of ('essentially bare LED element') 'lights' (are they bulbs, are they lamps, or what?!) in series. Other than that, and the attendant lack of need for electronics within each 'light', I'm not sure that I can think of any particular advantages.

I can certainly imagine that if 'bare LED element' bulbs/lamps/whatever started appearing significantly in the consumer marketplace, there would be a good few bangs (or, more likely, just "phutts"!) as a consequence!

Kind Regards, John

 

[333rocky333]

I'm not so sure about "less to go wrong". Every single such LED lamp has to contain some sort of (often quite crude) AC LV -> (usually DC) ELV 'power supply' - which is appreciably more complex than the electronics required for current control in those designed to be fed from a (single for several lamps) external power supply.

Kind Regards, John

Also regardless of what some people think, the stem and base bits run quite hot

 

[JohnW2]

Also regardless of what some people think, the stem and base bits run quite hot

Indeed - and I think that's almost all down to 'the electronics' (much more of which is needed in an 'LV' LED lamp/whatever). I don't think the LED elements themselves produce appreciable heat at all.

Kind Regards, John

 

[333rocky333]

Your right sometimes we change working ones to a different colour tone, the front and rim nice and cool, but touch the neck bit and jesus,

Been seeing a lot of twin fittings, with 2 of these in lately.
Whereas in the old days the 2 12volt Ar111 lamps would be in parralel on a 12 volt power supply.
The 2 led versions are wired in series and fed via a Constant Current driver.
I heard the main advantage of constant current drivers was that there more easier to tie in with the leading Dimmer formats used.

Not sure how it works, I assume its 12 of 1 watt elements in series and they drive them at the relevant current, i think there 15w 350ma drivers, were im lost, how comes you can also put them on 12 volt, what would limit the current then.
And why when 1 element dies the other 11 stay lit