Got to ask

[STI]

Just replaced my 5 MR16 Downlights in the bathroom with 5 MR16 LED's
Briiliant so far 250 watts down to 20, 5 transformers down to 2 (for security), lovely warm light very happy BUT every time i turn them on my DAB radio loses all signal.
It doesnt crackle it just stops dead. Instant i turn off the lights the radio comes back on. I have two DAB radios in two different rooms but both stop the instant the lights come on.

Strangely, for a short period i did have 4 LEDs and i left one 50 W lamp in place (the transformer) This set up did not effect the radio in any way.

Anyone eles experienced this, or can someone explain why its happening ?
Thanks

 

[securespark]

What are these lights running off?

 

[STI]

When you say running off ? they are on the lighting ciruit with a 0-60w transformer/inverter. The Radios are on a socket ring final. One radio in the bedroom one in the kitchen each about 30 foot away from the bathroom where the lights are. TV is not affected, sky box not affected wireless not affected just the DAB radio(s)

 

[securespark]

Are the transformers / inverters the right kit for the fittings?

 

[STI]

Yes i believe so. The LEDs are sold as direct replacements for existing installations, yeah i know dont laugh. But they work perfectly except for jamming the digital radio station. They did work fine with 5 transformers ie one to each light but i reduced this so that i could save on the tranies Just trtied Radio 4 extra via the computer and turn on the lights, works perfectly.

If the transformer isnt correct for the lights why would this effect the radio?
Nearby fluorescent works fine too. Sorry just adding all the thingsa that i can think of that sometimes cause or are effected by electrical interference

 

[SimonH2]

You've just found out why we have EMC regulations - without them you'd not have a working radio at all though certain vendors of PLT are keen to change that

Most likely it's an interaction between the transformer (I'm assuming a compact electronic jobby) which will be designed to supply incandescent lights (ie a resistive load) and the LEDs which will be very much not a resistive load*. The result is something that's electrically noisy up into the broadcast radio spectrum and connected with some nice bits of aerial wire.

With one halogen light connected, there will be a significant (50W ?) resistive load to keep the transformer a bit quieter. You may well find that things are better with a wirewound transformer. Better still, replace the existing setup with something designed to have LEDs from the outset - ie LED downlighters.

* Even if they are marked with CE markings etc, they coudl well be "cheap and nasty" lights that have been built without any PFC or filtering.

 

[RF Lighting]

Pop one of these in and you'll be good to go.

http://www.tlc-direct.co.uk/Products/TLT50slash1.html

 

[JohnW2]

... every time i turn them on my DAB radio loses all signal. It doesnt crackle it just stops dead. Instant i turn off the lights the radio comes back on. I have two DAB radios in two different rooms but both stop the instant the lights come on. The Radios are on a socket ring final. One radio in the bedroom one in the kitchen each about 30 foot away from the bathroom where the lights are. TV is not affected, sky box not affected wireless not affected just the DAB radio(s) ...

As has been suggested, I presume that you are suffering from (mains-bourne or radiated) 'EMC noise' from the 'transforners', coupled with fairly marginal signal strengths being received by the DAB radios (as with digital TV, weak/noisy digital radio signals result in 'nothing'{silence} rather than the crackling of analogue radios of the 'snow' of analogue TVs). Do either of the radios have external aerials (or provision for external aerials)? If not, have you tried moving the radios around a little, in the hope of increasing radio signal strength?

If the problem is mains-bourne EMC, you may be able to cure it with filtering. If radiated EMC, it could be more difficult. Of course, different/better/more expensive 'transformers' (hence probably less EMC) might also cure the problem. As has also been suggested by a couple of people, a wirewound 'transformer' would almost certainly cure the problem, since that's unlikley to produce any significant RF radiation/noise.

Kind Regards, John

 

[JohnW2]

... the transformer (I'm assuming a compact electronic jobby) which will be designed to supply incandescent lights (ie a resistive load) and the LEDs which will be very much not a resistive load*.
* Even if they are marked with CE markings etc, they coudl well be "cheap and nasty" lights that have been built without any PFC or filtering.

I'm not totally sure what you meant by that. LED lights will certainly present a non-linear load (which could be relevant), but there is unlikely to be a significant reactive component to the load. We also don't know whether the 'transformer' is supplying AC or DC. If (as seems the 'usual') it's DC, even if fairly rough DC, I would not have expected the lights themselves to produce appreciable EMC.

Kind Regards, John

 

[bernardgreen]

May not be mains borne, could be direct radiation from the lamps to the aerials in the DAB radios, TV isn't affected as its aerial is on the roof and highly directional, the computor get it's "radio" via the internet and doesn't use broadcast DAB signals.

It might be the fifth LED ( the last to be connected ) that is the culprit.

If the equipment is non compliant and as a result causing interference to neighbour's radio as well as your own radio then you should stop using it.

 

[STI]

Hi, firstly thanks to all for the replies. RF I will get one of those and try it.
But what i still cant get my head around is why its doing it now.
From the start the transformers have been the same 4 x 0-60W electronic and as it turned out 1 x 20- 60W.
So first config 5 x 50W halogens each with individual transformer--- No problem.
2ND config 5 x 4W LED each on own transformer - one flickering discovered the 20-60w transformer i didnt notice the radio situation but assume ok because
3rd config 4 x 4W led 1 x 50W halogen each on own transformer - No problem
Final (existing ) config 5 x 4W LED 2 x 0-60W electronic transformer - Radio issue.

So from the scenarios the LEDs dont seem to be the issue in themselves (unless its the fifth but i have just removed that and still the problem exists.) The problem seems to have occurred only when i reduced the transformers.
I have just tried removing the second transformer so all running on one, same problem.

So it seems by increasing the load on the transformer i have introduced the problem. Does this support the "noise" theory or should more transformers generate more "noise"

 

[Adam_151]

Consider also the cable lengths involved, I assume that with one tx per lamp, the cables to the lamp were short and with one doing mutiple lamps, there is much more cable on the extra low voltage side. It could be that the combination of an electronic transformer and electronic load has some resonance about it, and the length of cable is acting as a transmitting attenna.

 

[securespark]

Presumably you still have the tx's you took out?

The cheapest option would be to put them back how it was. At least you know it works.

Maybe RF could confirm whether or not the toroidal he recommends will be OK with longer cables to the fittings.

 

[bernardgreen]

Transformers using magnetic couplling at 50 Hz do not produce electrical noise that can be radiated,

The switched mode power supplies that are called "transformers" do produce electrical noise. The small transformeruse to supply extra low voltage lights are almost always switched mode power supplies. If it has a minimum load quoted then it is a switched mode power supply.

Switched mode power supplies operate at high frequency 20,000 Hz chopping thr voltage on and off so that the average is the desired output voltage.

In your set up you probably have a switch mode supply ( the "transformer" ) supplying another switched mode power supply controlling the current for the LED(s) in the lamps. Feeding a switch mode power supply with already chopped power can lead to all sorts of unstable operation and as a result generate excessive electrical noise.

 

[STI]

Presumably you still have the tx's you took out?

The cheapest option would be to put them back how it was. At least you know it works.

Maybe RF could confirm whether or not the toroidal he recommends will be OK with longer cables to the fittings.

Yes i do, but i am so pleased with the lights that i was going to put them in the kitchen and had hoped to save on tx's mind you i might go GU10 here and hopefully not get the same issue.

In answer to BernardG yes they are minimum load now zero -60. I might try a single tx 20-60W see if that makes any difference. Dont see why it should but worth a try.
In terms of cable runs they are now daisy chained and between each lamp on the ELV side is about 50cms its a small bathroom but with an awkward L shape hence the number of lights

Thanks