[SOLVED] change kitchen hood halogen to led

It has 2 halogen lights 20w and I first bought one circle led like this:
**broken link removed**

It worked! one halogen and one led and worked! I bought again another led to avoid heat of halogens, but when I tried both leds like this didn't worked.. it just flashes

So I tried another led that I thought It could be better, like this:
**broken link removed**

It didnt worked either. I am new to electronics so I open the kitchen hood (it's Neff) to see what power supply uses:
It has a NF40 Electronic Transformer for low voltage lamps the specs are:
PRI: 220-240VVac 50-60Hz 0,18A
λ=0,98
SEC: 11,5-12,5Vac 20....40W 3,5A max wires min 0,75mm^2
and last Dimmable by trailing edge dimmer

So is there any solution that I can use in both sides led or only a combination with halogen?

It has 2 halogen lights 20w and I first bought one circle led like this:
**broken link removed**

It worked! one halogen and one led and worked! I bought again another led to avoid heat of halogens, but when I tried both leds like this didn't worked.. it just flashes

So I tried another led that I thought It could be better, like this:
**broken link removed**

It didnt worked either. I am new to electronics so I open the kitchen hood (it's Neff) to see what power supply uses:
It has a NF40 Electronic Transformer for low voltage lamps the specs are:
PRI: 220-240VVac 50-60Hz 0,18A
λ=0,98
SEC: 11,5-12,5Vac 20....40W 3,5A max wires min 0,75mm^2
and last Dimmable by trailing edge dimmer

So is there any solution that I can use in both sides led or only a combination with halogen?

Click to expand...

Hi firejim

As i could understand you tried to replace halogens with Led but your effort has failed ! right ?
So , there is a simple solution , try to investigate about how those halogens were supply and how is their driving system and how is driving system of those LED lamps ? what you see is like some sort of mismatching here . so i think if you try to use another PSU for them it would work fine .

To be honest when i hear of kitchen it makes me so hungry ! ha ha ! so now here is 2:20 morning and i'm going to kitchen to make something to eat ! ;-)
Best Wishes
Goldsmith

goldsmith said:

Hi firejim

As i could understand you tried to replace halogens with Led but your effort has failed ! right ?
So , there is a simple solution , try to investigate about how those halogens were supply and how is their driving system and how is driving system of those LED lamps ? what you see is like some sort of mismatching here . so i think if you try to use another PSU for them it would work fine .

To be honest when i hear of kitchen it makes me so hungry ! ha ha ! so now here is 2:20 morning and i'm going to kitchen to make something to eat ! ;-)
Best Wishes
Goldsmith

Click to expand...

Yeah i tried to replace them. Someone told me that the psu maybe was fault and causes this, but when i put two halogens it works fine. You said to buy another psu, but what kind of specs? the same from the original? I think this PSU works with the fan extractor of the kitchen too. You said about the driving system, would you help me about this ? I know that the left socket powers first and then the right nothing more because has cover

lol wishes for eating

The most likely reason is the PSU is under-loaded with the LEDs. The Halogens draw about 1.7 Amps each so the load would be 3.4A, the LEDs probably draw considerably less.

The other reason may be that many dimmable Halogen supplies produce high frequency AC, usually in the 50KHz region. This isn't a problem with an incandescent load but it may be too high if your LEDs also have built in power supplies.

Brian.

So you suggest to change the psu? Could i found some leds that can cover high voltage like halogens?

We need to know the specification of the LEDs, unless they are purpose designed for full AC mains voltage, they probably need a low voltage DC supply. Halogen supplies are 12V but high frequency AC.

Brian.

Yeah i tried to replace them. Someone told me that the psu maybe was fault and causes this, but when i put two halogens it works fine. You said to buy another psu, but what kind of specs? the same from the original? I think this PSU works with the fan extractor of the kitchen too. You said about the driving system, would you help me about this ? I know that the left socket powers first and then the right nothing more because has cover

lol wishes for eating

Click to expand...

Hi Again
Now i can understand the exact reason behind of this ! some of the power supplies which are being used for halogens are dealing with specific topology , ( some kind of flyback or royer in some cases ) which if be without load they will get harm and voltage will try to be increased , but there is some kind of protection loop for them that works as hiccup which means turn on and turn off to prevent damages .
it can be one of the reasons behind of this effect . ( and your LEDs are not able to take enough current so the protection mode perhaps is coming in ! )
so , what's the solution ? there are many simple solutions for this . perhaps adding a high wattage and low value resistor in parallel to get more current and stop that behavior . or perhaps all of these thing are wrong and your LED driver is getting high frequency current from the line ( because of it's internally circuit ) so it has some effects on the preceding stage which is halogen supply .
Anyway , you can have another way , as designing a simple supply for that which i can guide you for this . or perhaps buying another supply for that .

In all of those cases i can guide you .

Yeah ! eating was wonderful ! ha ha ! ;-)

Good Luck
Goldsmith

Thanks again for your time, Could you suggest me how to add a high wattage and low value resistor in parallel to get more current and stop that behavior? I would like to try it. Remember that I dont have too much space in the area of the light.

I wouldn't do it that way. The resistors would be consuming the extra current and simply turning it into heat. Your next problem, especially in a small space would be how to keep them from overheating.

Tell us what kind of LEDs you want to use, it will probably be far easier to forget the existing PSU and replace it with one dedicated to driving LEDs.

Brian.

betwixt said:

I wouldn't do it that way. The resistors would be consuming the extra current and simply turning it into heat. Your next problem, especially in a small space would be how to keep them from overheating.

Tell us what kind of LEDs you want to use, it will probably be far easier to forget the existing PSU and replace it with one dedicated to driving LEDs.

Brian.

Click to expand...

I would like to try it with resistors, and i could put some kind of aluminum piece. I already said what kind of leds I am using

The links to the LEDs don't work for me.

To fully replace the halogen lamps with resistors you would need 7.5 Ohms rated at more than 20W for each lamp. In reality the resistor value would have to be higher than that but a full LED specification is needed to know by exactly how much.

However, I don't think this will fix your problem. The output of the existing halogen transformer will be pulsed high frequency AC which is fine for incandescent halogen lamps but will not work with the rectifiers in most other AC driven equipment which is designed for 50 or 60 Hz. Even if it worked at all, it would strain the rectifiers and they would probably burn out very quickly.

Brian.

look at this link:
**broken link removed**
I have also two of these.

Got it!

No, do not use these with the original halogen supply! The rectifiers on them are only rate dfor use on a normal 50Hz or 60Hz suppy. The halogen supply may be producing 1,000 times that frequency and the rectifiers will cook.

The best option is simply to remove the original supply and replace it with a small transformer to drop your incoming AC mains suppy down to 12V then wire it directly to the LEDs.

Brian.

Thanks for your advice but what about the extractor fan -hood? I dont know where it gets power supply? maybe the same psu?

The fan is almost certainly running directly from the incoming AC supply. There would be no economical reason to use a low voltage fan and provide a step-down supply to feed it.

Brian.

I've been planning that for ages. Sometimes they just wont die! So far in the three years I've planned for LED replacements, I only have 6 fittings that have LEDs.

A table lamp with 4W Ikea LED replacing a 40W incan,
a G4 12V 3W LED replacement for a 25W halogen G4 desklamp,
a dimmable 7W E14 in a bedside lamp replacing 8W CFL,
two 4W LED candles in the rangehood replacing the original 40W incans,
and an 11W R80 in the bathroom replacing a 75W R80.
One halogen incan probably can't be replaced as it is in a dimmer that doesn't play nice, the rest are all CFL that last and last.