Convert Halogen fitting to LED

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Paul Tydeman

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I want to change a couple of light fittings in our hall from Halogen to LED so we can get bright white bulbs to brighten it up a bit rather than the dull yellow halogens. The current light fittings are driven by Kaoyi KTB-60 and the fittings take 6 x 10W G4 halogen bulbs. We don't want to buy new light fittings as we like the ones we have.

I know I'll need to change the transformer and just wanted to validate that if we were to replace the existing transformer with one rated 0W-50W (like this one on Amazon https://www.amazon.co.uk/0W-Dimmable-Electronic-Transformer-voltage/dp/B00IWCG502) then this would still do the job and drive 6 1.5W LEDs?

Thanks!
 
DetlefSchmitz said:
It would be educational to learn from you what it is you consider to be wrong with this product.
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G4, GU5.3 etc LEDs usually say on them DC or 50/60Hz AC or words to that effect. They are NOT designed to work at 10s of kHz that the switch mode supply linked to provides.

There, you have been educated.
 
Yeah good one winston. Those open terminals look really safe :eek: also you are recommending a DC power supply for lamps which are marked as AC at their supply terminals.

Paul please ignore anything which Winston writes. He is not an electrician and most of his posts are either unhelpful, wrong, or like this one, actually dangerous (and wrong)

The power supply you linked to in your first post will be fine with the LEDs you’ve linked to.
 
winston1 said:
G4, GU5.3 etc LEDs usually say on them DC or 50/60Hz AC or words to that effect.
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They never say DC, because the connectors on those lamps and the sockets they fit into are not polarised. It would be impossible to determine the correct way to insert them.
 
There is some truth in all that has been said, including @winston1 but the problem is the lighting industry is it seems unable to label or give useful specification for their products, this company specialises in 12 and 24 volt DC lighting however in the main lights bought from high street shops are either 12 volt or 230 volt AC.

The problem is even if this toroidal transformer transformer.jpg is ideal to comply with 50 Hz 12 volt AC supply, it can't be used with a dimmer switch, and at £19 is not cheap rated 50 watt. The 0 - 50W you selected will likely work OK, but the likely is the operative word, the kHz range of output could turn the set up into a mini wireless transmitter if the cables happen to hit the right length for the frequency. Also dimming any electronic lamps can cause problems where the power supply/driver/transformer/ does not match the switch, specially where the switch does not require a neutral, and this includes both 12 volt and 230 volt lamps.

You should not dim quartz lamps so likely no problem using a toroidal transformer this is how I would do it, but I have a 200 watt toroidal transformer spare, so don't need to spend £50 on a new one. I have some G9 bulbs 4 x LED and 1 x quartz, in the same chandelier and lucky you can't tell which is which, and that is likely the easy way to move to LED leave one quartz in the circuit. However you seem to want a very high colour temperature, I have never considered quartz lamps to be yellow, I have always considered them to be if anything too white.

So maybe something wrong to start with?

LED is a DC current dependent device, but in the package of a bulb they are often designed to work on AC at a fixed voltage, and to do that the AC needs to be made into DC and some current limiting device added. One would hope the rectifier in 12 volt versions would take either AC or DC but there is nothing on most bulbs to say that, I have mainly LED lighting in the house, only two have ever failed, one replacement LED tube for a fluorescent lamp, and one G9, but at £5 for a bulb one does not want too many failures, so with the power supply you linked to and the one @winston1 linked to you are taking a risk, they may work, or it could become a transmitter or could over load the rectifying diodes, as put DC into an AC bulb and double the average current goes through a diode in most cases.

If you have access to fit the larger toroidal transformer I show then I would use one of them, but if the transformer is to fit through the hole where lamp fits, I would take a chance and fit the one you linked to in your first post. There is no right or wrong, just shades of grey.
 
flameport said:
They never say DC, because the connectors on those lamps and the sockets they fit into are not polarised. It would be impossible to determine the correct way to insert them.
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They often say DC or AC 50/60Hz. They have a bridge rectifier in them (as they must to operate on AC) so it does not matter which way you insert them.
 
RF Lighting said:
Yeah good one winston. Those open terminals look really safe :eek: also you are recommending a DC power supply for lamps which are marked as AC at their supply terminals.
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If you care to scroll down that eBay listing there are other DC supplies there with shrouded terminals.

Don’t use a tens of kHz supply on lamps designed for 50/60Hz then complain they don’t last.
 
winston1 said:
They often say DC or AC 50/60Hz. They have a bridge rectifier in them (as they must to operate on AC) so it does not matter which way you insert them.
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The GU10 lamps I have found where anything to do with AC/DC is printed on them simply says 50 Hz, and likely the only reason to print 50 Hz is the number of people who try and use them with a 35 - 105 VA output power supply, and it is there as a get out clause should anyone complain it does not work.

I went through the whole of the Screwfix listing to see what they said, and not a single listing said AC or DC, however the picture of the product often showed the 50 Hz marked on bulb. How long a bulb lasts is mainly down to luck, there is some fire house in USA with a filament bulb still burning after over 100 years, although the light output is so low can't really see point other than get in record books.

I would not think the LED lamp works any different be it 50 Hz or 50000 Hz likely the only difference is the stroboscopic effect, which will reduce as frequency increases. The big thing is a toroidal transformer is heavy and big, (63 mm) so having that weight on the ceiling and getting it through the hole that the light fits into could be a problem, so there is a good reason for using a 0 - 50 VA electronic device which is light and will fit through the hole. Yes the light may say 50 Hz but that means you should not use DC as well as not using kHz AC, both could cause problems, and both are in real terms unlikely to cause problems.

So using a DC power supply instead of a kHz power supply is really the pot calling the kettle black, neither is correct, but both will likely work.
 
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