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12V lighting transformers

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D.M. Procida

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Jun 13, 2012, 7:18:50 AM6/13/12
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I have an IKEA Norrsken set of lights - a transformer, two cables that
strecth across the ceiling to suspend individual lights from, and a set
of lights.

The English instructions say: "not designed to take more than 5-7
spotlights. Max 140W."

The Italian instructions say: "designed for 5-7 spotlights. Max 140W."

These don't mean the same thing!

The Portuguese sounds more like the English: "mais do que 5-7" and the
French more like the Italian: "the system can only support 5-7
spotlights".

So, the transformer is rated for 140W; what would likely happen with
only say 4 lights mounted on the cable tracks?

Daniele

Rod Speed

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Jun 13, 2012, 7:34:24 AM6/13/12
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"D.M. Procida" <real-not-anti...@apple-juice.co.uk> wrote in
message
news:1klmn7d.19q7ua319zbpv8N%real-not-anti...@apple-juice.co.uk...
It'll be fine. If having say 4 would kill it, they would say that
explicitly.

What does the swedish text say ?

Dave Liquorice

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Jun 13, 2012, 7:52:00 AM6/13/12
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On Wed, 13 Jun 2012 12:18:50 +0100, D.M. Procida wrote:

> So, the transformer is rated for 140W; what would likely happen with
> only say 4 lights mounted on the cable tracks?

Is the transformer a large heavy thing or small and light weight?

If it's large and heavy it's a lump of iron with windings, if it's
not properly loaded the voltage might be a bit high, shortening the
life of the bulbs present.

A smaller light weight transformer is most likely electronic and will
have much better regulation and having a lower load on it shouldn't
be a problem.

Of course the other problem with that description is that bulbs come
in different wattages. You could have 7 x 20W = 140W or 2 x 50W + 2 x
20W = 140W. Assuming the fittings are rated for a 50W bulb...

--
Cheers
Dave.



Andrew Gabriel

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Jun 13, 2012, 8:11:24 AM6/13/12
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In article <1klmn7d.19q7ua319zbpv8N%real-not-anti...@apple-juice.co.uk>,
12V lighting transformers have no active voltage regulation,
and rely on the load being within a given range to keep the output
voltage within limits. That's why you'll see ratings like 20W-60W.
Something like that should be on the transformer's rating plate.

Electronic transformers have a low internal impedance, and the
min output is usually less than half the max output. Magnetic
transformers have a much higher internal impedance and usually
can't cope with such a wide load range whilst keeping the output
voltage within spec, and the min load may be nearer to the max
load.

All the electronic transformers I've come across will auto shutoff
with too low a load, but I don't know if that's the case with all
of them. Magnetic transformers don't have any such auto-shutoff.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

Dave Plowman (News)

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Jun 13, 2012, 8:12:14 AM6/13/12
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In article
<1klmn7d.19q7ua319zbpv8N%real-not-anti...@apple-juice.co.uk>,
Is it a transformer or power supply? A transformer will be heavy - a PS
not.

If a PS it will usually give the load range on it - like say 50-150 watt
or whatever. A transformer will supply a slightly higher voltage if not
running at full load so the life of the bulbs may suffer.

--
*How many roads must a man travel down before he admits he is lost? *

Dave Plowman da...@davenoise.co.uk London SW
To e-mail, change noise into sound.

D.M. Procida

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Jun 13, 2012, 8:51:26 AM6/13/12
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D.M. Procida <real-not-anti...@apple-juice.co.uk> wrote:

> So, the transformer is rated for 140W; what would likely happen with
> only say 4 lights mounted on the cable tracks?

It's big heavy transformer - no sign of any electronics in there except
for a cut-off fuse.

The light fittings all take only 20W halogen bulbs.

So, I guess with four lights only it will eat up all the bulbs.

Daniele

www.GymRatZ.co.uk

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Jun 13, 2012, 9:34:38 AM6/13/12
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On 13/06/2012 13:12, Dave Plowman (News) wrote:

> Is it a transformer or power supply? A transformer will be heavy - a PS
> not.

A transformer is only a component part of a type of power supply.
The weight would be significantly different if the "power supply" was
either a switch mode unit (the light one) or using a direct transformer
output (heavy one).


--
http://www.GymRatZ.co.uk - Fitness+Gym Equipment.
http://www.water-rower.co.uk Rowing machines and stuff

Dave Plowman (News)

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Jun 13, 2012, 10:11:44 AM6/13/12
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In article <jra4tj$qf2$1...@dont-email.me>,
www.GymRatZ.co.uk <0845.86...@GymRatZ.Gym.Equipment> wrote:
> On 13/06/2012 13:12, Dave Plowman (News) wrote:

> > Is it a transformer or power supply? A transformer will be heavy - a PS
> > not.

> A transformer is only a component part of a type of power supply.
> The weight would be significantly different if the "power supply" was
> either a switch mode unit (the light one) or using a direct transformer
> output (heavy one).

Yes, pet.

--
*Even a blind pig stumbles across an acorn now and again *

NT

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Jun 13, 2012, 12:43:44 PM6/13/12
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On Jun 13, 1:51 pm, real-not-anti-spam-addr...@apple-juice.co.uk (D.M.
Procida) wrote:
A 140w 50Hz transformer might have a regulation of around 5 or 10%.
4x20w=80w, so the output voltage would have increased from max load
level to the same plus 2.5-5%. If the transformer is designed to be
say 1.5% undervoltage at peak load, the overvoltage would now be
1-3.5%.

life is proportional to voltage^13

efficacy is proportional to voltage^1.9

color temperature is proportional to voltage^0.42


So mean bulb life would shift from 1500hrs to 1320-960 hrs
efficacy would improve 1.9% - 6.7%
CCT would move up from 3000K to 3012K - 3043K


NT

John Rumm

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Jun 13, 2012, 12:59:47 PM6/13/12
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You will probably get through bulbs quickly... Assuming its a typical
ikea iron cored lump, then its output voltage will rise out of spec if
lightly loaded.

The simple fix is to extract the transformer and replace it with an
electronic one of appropriate size.

--
Cheers,

John.

/=================================================================\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\=================================================================/

Andy Champ

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Jun 13, 2012, 3:31:46 PM6/13/12
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On 13/06/2012 17:43, NT wrote:
> efficacy is proportional to voltage^1.9

ITYM efficiency.

Andy

NT

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Jun 14, 2012, 5:09:45 AM6/14/12
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no


NT

丽琴 方

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Jun 14, 2012, 6:03:54 AM6/14/12
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On 6月13日, 上午7时18分, real-not-anti-spam-addr...@apple-juice.co.uk (D.M.
there may be something wrong with the transformers, are you sure
there's nothing wrong with it? or you could buy new one.

NT

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Jun 14, 2012, 6:44:52 AM6/14/12
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Adam Aglionby

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Jun 14, 2012, 7:27:05 AM6/14/12
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Electronics either tend to use the long lines as TX aerials or they
don`t like the impednace/capacitance of the line and shut down, hnce
use of iron trafos on exposed wire systems.

Cheers
Adam

Andy Champ

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Jun 14, 2012, 4:34:25 PM6/14/12
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You live and learn! Thanks.

It seems I'm not alone though: "so it is not uncommon to see
"efficiencies" expressed in lumens per watt, or "efficacies" expressed
as a percentage."

Andy

John Rumm

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Jun 14, 2012, 6:06:43 PM6/14/12
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On 14/06/2012 12:27, Adam Aglionby wrote:
> On Jun 13, 5:59 pm, John Rumm<see.my.signat...@nowhere.null> wrote:
>> On 13/06/2012 12:18, D.M. Procida wrote:
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>> I have an IKEA Norrsken set of lights - a transformer, two cables that
>>> strecth across the ceiling to suspend individual lights from, and a set
>>> of lights.
>>
>>> The English instructions say: "not designed to take more than 5-7
>>> spotlights. Max 140W."
>>
>>> The Italian instructions say: "designed for 5-7 spotlights. Max 140W."
>>
>>> These don't mean the same thing!
>>
>>> The Portuguese sounds more like the English: "mais do que 5-7" and the
>>> French more like the Italian: "the system can only support 5-7
>>> spotlights".
>>
>>> So, the transformer is rated for 140W; what would likely happen with
>>> only say 4 lights mounted on the cable tracks?
>>
>> You will probably get through bulbs quickly... Assuming its a typical
>> ikea iron cored lump, then its output voltage will rise out of spec if
>> lightly loaded.
>>
>> The simple fix is to extract the transformer and replace it with an
>> electronic one of appropriate size.

> Electronics either tend to use the long lines as TX aerials or they
> don`t like the impednace/capacitance of the line and shut down, hnce
> use of iron trafos on exposed wire systems.

Most modern ones don't seem that fussy. It may depend on the length of
wire etc. I have swapped iron cored ones for electronic SMPSU style ones
in the past in similar circs. (also on an Ikea light as it happens,
where they only offered "buying a new set" as a source of parts)

Nicolas

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Jun 16, 2018, 1:14:05 AM6/16/18
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replying to John Rumm, Nicolas wrote:
I have the same set. It was run with 6x20W halogen bulbs since 2005 and not a
single bulb has burn in this time period.
Two months ago, I replaced all the halogen MR16 with Philips LED 6.5W plus a
Lutron Casetta Dimmer. Since then, the whole rail has a tendency to flicker.

I know that the load has gone from 120W to 39W so the load might be too low.
Also, I undertand that dimmers don't work all the same between ELV, forward
phase, reverse phase, TRIAC. This is not common language to me as it's hard
to find the spec of this old tranformer | power supply, the Casetta dimming
mode and the preferred dimmer of thos Philips bulbs.

Being already in mid 2018, what would you suggest, John, to solve the problem ?

Thanks

--
for full context, visit https://www.homeownershub.com/uk-diy/12v-lighting-transformers-814037-.htm


Brian Gaff

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Jun 16, 2018, 2:41:16 AM6/16/18
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Ohm that weird web site again.
Right I have a 12 v transformer from Ring lighting. all it is is a crude
transformer in a box supplying AC at nominally 12 v. and to my mind trying
to get leds to work may well be as crude as them only running on one mains
half cycle. does anyone actually know if these are really able to use the ac
12v or are they crudely rectifying one cycle of the ac internally?
I am in the market for new garden lights as the old ones tungsten filament
ones are now intermittent.
I need bulbs that can illuminate a globe visible in the dark. My sight is
almost down to light perception and I really need a large blob of light to
be able to see where my property is.
Brian

--
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This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...
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Blind user, so no pictures please!
"Nicolas" <caedfaa9ed1216d60ef...@example.com> wrote in
message news:u01VC.357065$9t.5...@fx26.am4...

Dave Plowman (News)

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Jun 16, 2018, 5:42:36 AM6/16/18
to
In article <u01VC.357065$9t.5...@fx26.am4>,
Nicolas <caedfaa9ed1216d60ef...@example.com> wrote:
> replying to John Rumm, Nicolas wrote: I have the same set. It was run
> with 6x20W halogen bulbs since 2005 and not a single bulb has burn in
> this time period. Two months ago, I replaced all the halogen MR16 with
> Philips LED 6.5W plus a Lutron Casetta Dimmer. Since then, the whole
> rail has a tendency to flicker.

> I know that the load has gone from 120W to 39W so the load might be too
> low. Also, I undertand that dimmers don't work all the same between
> ELV, forward phase, reverse phase, TRIAC. This is not common language
> to me as it's hard to find the spec of this old tranformer | power
> supply, the Casetta dimming mode and the preferred dimmer of thos
> Philips bulbs.

> Being already in mid 2018, what would you suggest, John, to solve the problem ?

Not sure there is any benefit in using 12v LEDS over mains. Dimmable 12v
LEDs are rather more expensive than mains ones too. TLC suggest if you
want to dim them you need a purpose transformer and dimmer.

I have a chain of GU10 on a dimmer which work pretty well. So might have
made more sense to convert your fittings to those - if possible.

But since you've already bought them, I'd investigate a transformer
designed for dimming LEDs.

--
*WHAT IF THERE WERE NO HYPOTHETICAL QUESTIONS?

John Rumm

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Jun 16, 2018, 7:18:12 AM6/16/18
to
On 16/06/2018 10:35, Dave Plowman (News) wrote:
> In article <u01VC.357065$9t.5...@fx26.am4>,
> Nicolas <caedfaa9ed1216d60ef...@example.com> wrote:
>> replying to John Rumm, Nicolas wrote: I have the same set. It was run
>> with 6x20W halogen bulbs since 2005 and not a single bulb has burn in
>> this time period. Two months ago, I replaced all the halogen MR16 with
>> Philips LED 6.5W plus a Lutron Casetta Dimmer. Since then, the whole
>> rail has a tendency to flicker.
>
>> I know that the load has gone from 120W to 39W so the load might be too
>> low. Also, I undertand that dimmers don't work all the same between
>> ELV, forward phase, reverse phase, TRIAC. This is not common language
>> to me as it's hard to find the spec of this old tranformer | power
>> supply, the Casetta dimming mode and the preferred dimmer of thos
>> Philips bulbs.
>
>> Being already in mid 2018, what would you suggest, John, to solve the problem ?
>
> Not sure there is any benefit in using 12v LEDS over mains. Dimmable 12v
> LEDs are rather more expensive than mains ones too. TLC suggest if you
> want to dim them you need a purpose transformer and dimmer.

12V is the only option in this case, since the lamps are suspended from
a pair of uninsulated support wires that stretch across the room. They
also carry the power.

> I have a chain of GU10 on a dimmer which work pretty well. So might have
> made more sense to convert your fittings to those - if possible.
>
> But since you've already bought them, I'd investigate a transformer
> designed for dimming LEDs.

Yup that would be my fix, swap out the iron lump transformer in the wall
mounted bit, and put in a suitable electronic transformer.

John Rumm

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Jun 16, 2018, 7:19:08 AM6/16/18
to
On 16/06/2018 06:14, Nicolas wrote:
> replying to John Rumm, Nicolas wrote:
> I have the same set.  It was run with 6x20W halogen bulbs since 2005 and
> not a
> single bulb has burn in this time period.
> Two months ago, I replaced all the halogen MR16 with Philips LED 6.5W
> plus a
> Lutron Casetta Dimmer.  Since then, the whole rail has a tendency to
> flicker.
>
> I know that the load has gone from 120W to 39W so the load might be too
> low. Also, I undertand that dimmers don't work all the same between ELV,
> forward
> phase, reverse phase, TRIAC.  This is not common language to me as it's
> hard
> to find the spec of this old tranformer | power supply, the Casetta dimming
> mode and the preferred dimmer of thos Philips bulbs.
>
> Being already in mid 2018, what would you suggest, John, to solve the
> problem ?

Same as I did back then, swap the transformer for an electronic supply
of appropriate size for the load.

Tim Watts

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Jun 16, 2018, 8:38:24 AM6/16/18
to
On 16/06/18 10:35, Dave Plowman (News) wrote:

> But since you've already bought them, I'd investigate a transformer
> designed for dimming LEDs.
>

RS sell a very nice range:


https://uk.rs-online.com/web/p/led-drivers/8904449/

Not cheap, but you get what you pay for. I've got some of the same make,
non dimmable.

Key things I like about this range:

1) Proper cable terminations, shrouded with strain relief. I am really
not sure how some of the junk sold in wholesalers with single insulated
wires sticking out can possibly be made to conform to IET Wiring Regs
unless you re-enclose the whole thing.

2) Over-everything protection. I prefer my SELV PSUs to not catch fire...

However, I did get a cheaper SELV unit from TLC a long time ago driving
12V incandescent.


However, in neither case can I vouch for how well they will work with LEDs.


There's another solution, which is to have an always on 24V SELV PSU,
non dimmable and use a remote dimmer module:

https://www.vesternet.com/z-wave-qubino-flush-dimmer-plus

That's cute as it will do mains OR 24V (but not 12V). 24V LEDs are not
uncommon.


It's really a ZWave device, but it can be hard wired to a push button
switch (various momentary switches are available, GET/Schneider do a
nice GRID push button and for pull cords, use an MK "disabled" alarm and
swap the red cord for white - the switch body is the same as normal.

I've done that, but on mains with Fibaro dimmers - but I am considering
adding Qubinos for 24V LED dimmable lighting upstairs (and maybe even RGBW).

Andrew Gabriel

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Jun 16, 2018, 4:14:04 PM6/16/18
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In article <pg2be9$cft$1...@news.albasani.net>,
"Brian Gaff" <bri...@blueyonder.co.uk> writes:
> Ohm that weird web site again.
> Right I have a 12 v transformer from Ring lighting. all it is is a crude
> transformer in a box supplying AC at nominally 12 v. and to my mind trying
> to get leds to work may well be as crude as them only running on one mains
> half cycle. does anyone actually know if these are really able to use the ac
> 12v or are they crudely rectifying one cycle of the ac internally?

The few 12V G4 LEDs I've dissected all have full wave rectifiers.
If they are marked not dimmable, they have a smoothing capacitor
too. Otherwise they flicker at 100Hz, which is only noticable if
they are moving across your field of view (or something they are
lighting is moving across your field of view) and this is not
really an issue.

> I am in the market for new garden lights as the old ones tungsten filament
> ones are now intermittent.
> I need bulbs that can illuminate a globe visible in the dark. My sight is
> almost down to light perception and I really need a large blob of light to
> be able to see where my property is.
> Brian
>

--
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