/ Home & Energy, Technology

The energy-saving LED bulb that switched off the radio

An LED bulb lighting up the darkness

We get sent some weird and wonderful tales of products going wrong, but one story piqued our interest so much that we just had to send it to the lab to test it out. Can you help us shed more light on the mystery?

Last year we received this intriguing message:

‘I recently changed six halogen down-lighters to more energy efficient LED bulbs. Unfortunately when the lights were switched on, the DAB signal on my radio was wiped out!’

To try and figure out this conundrum, we sent a batch of cheap, generic 12V LED bulbs to our lab and found that when a digital radio was placed within a few metres of the switched-on bulbs the signal went fuzzy. When the radio was placed within a few centimetres of the LED bulbs, it cut out all together.

The plot thickens

LEDs are ultra energy efficient light bulbs that can last up to twenty years and have been hailed as the future of home lighting.

It seems our members are not the only ones who have had this problem. There are other accounts of LED bulbs affecting radios, with AVForums also collecting stories. Nick Tooley shared his experience:

‘I had the same problems with LED bulbs wiping out DAB reception and tried several types of bulbs, but to no avail.’

And it seems that the issue may not just be limited to digital radios – TVs may also be affected. After fitting LED down-lighters in his kitchen, Jackord noticed the following problem:

‘While the lights are much better, we then by accident noticed that the digital TV would not work (I was complaining that we had no reception at all, did not make any sense, began to think that there had been some sort of catastrophic disaster which stopped the TV stations from broadcasting…lol) then someone turned off the ceiling lights in the kitchen and, hey presto, on came the TV.’

Shedding light on cheap bulbs

So what bulbs are affected? We tested three 12V generic LED bulbs and we also compared them to branded 240V GU10 LEDs and some halogens. We found only a very minor interference with our radio signal. So at this stage, the issue seems to be limited to cheap knock-offs rather than branded goods.

We’ve only done preliminary tests on this problem, so can’t make any concrete conclusions on why this is happening or how widespread this bizarre problem is.

That’s where you come in. We need your help – have you had this problem? If so, please enlighten us in the comments below, including what model bulb you were using and where you bought it.

Comments
Guest
Prius owner Hoffman Estates, IL says:
24 September 2017

I have a 2014 Prius C that uses standard halogen bulbs for the headlights. About two years ago I upgraded to a set of LED low beam bulbs. They were 4-Phillips-Luxeon 45 WT 4,500 Lumen bulbs that were powered by the standard H11 12V connector. There was no additional power supply between the LED bulb and the 12V connector.

When I installed the LED bulbs, I noticed that when I turned on the LED headlights I Lost several FM radio stations that I like to listen to. Turned the lights off, and the radio stations were back on. This is the standard FM HD radio that comes with the Toyota Prius C with the standard stubby radio antenna on the rear of the roof. OK, I started listening to a collection of music on the USB port, so no big problem.

Yesterday, my driver’s side LED burned out. Now I have choice of selecting a new set of LED bulbs. I noticed there are some LED bulbs that have power supplies between the 12V H11 connector and the LED bulb. Does anyone have any suggestions for my new LED bulb purchase that might return my distant FM stations when the headlights are on. Thank you.

Guest

Prius owner-There is no need for voltage conversion at a 12V DC input Led,s are okay at that voltage, its the current drive that counts . Led,s are arranged In a circuit that equalises the current but they are susceptible to over current/voltage . What you might have seen as “power supplies ” would ( in a automobiles case ) be surge suppressors which look like “supplies ” maybe incorporating blocking for re-entrant noise/RF interference from getting back into the battery supply and hence your radio .On the other hand IF it is RF Radiated via the air then you will need to suppress the radio with an earthed metallic covering and up rate your co-ax to the aerial making sure the outer braiding is well earthed . Two different types of possibilities .

Guest

Duncan – I expect that the power supply used with some LED bulbs is there it stabilise the voltage to maintain constant brightness and possibly to prolong the life of the lamps. When the battery is being charged the voltage can rise to approaching 15 volts.

Guest

Wavechange -did you not read my post staying -“surge protectors” they can incorporate stabilisation using zenner diodes etc . IF you are talking of full blown stabilisation power supplies then that is very costly and quite large even in this day+age. surpassing the cost of the bulbs.

Guest

I take your point about surge (voltage spike) protectors but I was referring to voltage stabilisation. I have no idea of the costs involved. I agree with your suggestion about screening wiring.

Prius owner has mentioned obtaining new LED lamps. My suggestion would be to explain to the supplier that the lamps must not cause interference. If there is any problem then it should be easy to get a refund.

Guest

All my own build power amps+pre-amps had fully stabilised power supplies . The supplies had to be of the same high calibre as the amps themselves . Obviously it was all discrete analogue . they did not require much in stabilisation unlike the plastic modern SMPS stabilised versions which in my book are vastly inferior in an top end hi-fi setting. . You could get away with it in a small current pre-amp but not in a high power amp if it is run in Class A . Good amps had small value compensation capacitors usually polystyrene or polypropylene using high quality plastic not the cheap bin liner quality . They weren’t cheap to buy in very low loss types at high voltage dielectric absorption ( polystyrene ) = 0.00001@100Mhz they cost the earth now.

Guest
Old Fogie says:
27 October 2017

Bought “Lumilife” LED direct replacement bulbs for 50W halogen GU 5.3. Worked with existing 12v AC supply and light output good. Did not notice problem until darker mornings when lights in bathroom on at same time as morning radio alarm. Then FM radio signal completely drowned out by “white noise” interference.
Tried adding Ferric Chokes to lamp LV supply but no improvement. Did notice that Philips bulbs with higher light output did not affect radio. Spoke to supplier who said this ws normal fo LED bulbs and nothing could be done except moving radio further away. (Not possible because already on opposite side of bedroom from bathroom.) Tried experimenting with aluminium foil shielding around base of bulb where rectifier situated but no difference.
Then moved aerial for radio and suddenly no interference.
So if you have issues with LED bulbs affecting FM radio try moving/adjusting the aerial or even rotating the radio.

Guest

As you have found out Old Fogle the modern day “cure all Ferric Chokes don’t work with radiated interference of as high strength. While you tried the dodge of tin foil , which I hope you earthed , a better answer , if you could get it would be mu-metal. The higher the radio frequency transmission of a signal to your radio like FM and above the more directional it is this is exacerbated by universal use of Ferrite Rod aerials . Gone are the days of long wire aerials which are more multi directional. and which can be tuned by small value aerial capacitor’s have found that it is possible ( depending on the SMPS circuit for a heavier load to actually reduce the RF generated interference . You found like and old Wireless man ,like myself , a dying breed I am afraid . I had the same problem when working for BT when a digital telephone system kept on losing its programming in a factory due to heavy welding equipment . No amount of wire wound Ferrite core chokes worked neither did shielding the box holding the CPU /cards , in the end the box had to be moved. its a different matter if its only interference feedback into the mains circuit. Us “Old Foggies ” could teach the younger generation a thing or two but modern day social interaction is against that.

Guest

Old Fogie – I have been looking at the problem of radio interference by LED lighting for a few years now, and have now met people who have experienced problems, as well as reading about them on this and other websites. Problems seem to be more common with the 12V MR16/GU 5.3 lamps and could originate in the lamp or the driver, with the interconnecting wire effectively acting as an aerial for transmission of radio interference. Some have used ferrite products or screening (as Duncan mentions). It’s a good idea to move the radio or aerial, as you have suggested.

I suggest asking the retailer to replace the problem lamps or provide a refund. If enough people do this and give negative reviews then they might change their supplier.

Another approach would be to switch to mains voltage LEDs such as GU10s. These obviously don’t need drivers and I’ve seen fewer complaints about radio interference.

Guest
Mike Fulton says:
30 October 2017

I have recently (October 2017) installed a 13-watt Philips LED bulb in a bedside lamp, the bulb being at approximately 110 mm from the antenna of my FM radio. When the bulb is switched on, there is continuous interference, but not such as to completely blot-out reception of the station concerned (usually Radio 4).

Guest

I expect that if you move the radio away from the lamp, the interference will disappear. Light dimmers, microwave ovens and routers can also create problems at very close range and it will be more of a problem if you have a weak radio signal. It can be explained by the inverse square law. You might find that other LED bulbs work fine next to a radio but it’s best to keep them apart.

Guest
AndyT says:
6 January 2018

Same here but with one of those unbranded “classic” looking led bulbs in my bedside light.

Guest
Debra Saunders says:
18 November 2017

We just installed in the kitchen a 32 watt led ceiling light r-sunrise £16.49 from Amazon, now I have almost no reception in my fm rafio

Guest

I bought energy efficient led bulbs for my bedside lamps from Sainsbury’s. Since fittin them my dab radio only works when the bedside lamp is off. Do I have a right to return them?

Guest

There is no harm in trying, Jo. Before you do, it’s worth checking if moving the radio away helps – for example to the other side of the bed.

Guest
MKING says:
24 November 2017

We have A neighbour who has recently installed a rectangular floodlight in his back yard which is motion sensitive and has a dawn-to-dusk sensor. When the light is activated our FM reception is destroyed and a replaced with a very loud spitting/buzzing distortion for the two minutes that the light is active. The light is 8 METRES from the antenna which is an extended loop wire which gives a good stereo signal; the distortion is as bad when the radio is switched to mono.

This light has an internal power supply and probably a non-replaceable bulb unit. OFCOM (via the BBC) are being polled for action but it is not easy to get them out of their comfortable seats…

Guest

You have brought up a subject dear to my heart M.KIng — the “downfall ” of the GPO Radio Interference Group . I new a guy when I worked in BT who was in it. He went on at length that the government was “rationalising it -ie- as it has done to other government departments – removed its power , reduced its staff and turned it into another NGO that cannot do what the public want due to lack of resources . Your best bet is to change the direction of the loop wire and possibly replace it with a vertical aerial which extends outside the radiation area of the light . You could try putting a metal screen between the light and the aerial and earthing it . Normal RF transmissions form a pattern but you need to know the frequency of the signal to judge the pattern .If you use good quality screened tv/satellite cable and fix the vertical aerial higher up on your house that would help by being maybe outside the transmitted radiation field At the time private enterprise was complaining that the GPO service was “too good ” at detection and was causing them problems involving profit .

Guest

I would suggest having a word with your neighbour, who may be able to reject the floodlight as unsatisfactory. If they have paid to have it fitted, they might be less helpful. I once reported a radio interference problem caused by neighbours and it was dealt with promptly, but that must have been 35 years ago.

I would be very interested to know the outcome.

Guest

There is a legal remedy but I suggest you do what Wavechange has suggested in the first place. Your neighbours might not have been aware of the interference their floodlight has caused. You don’t have to put up with it or go to significant expense to curtail it so it might be helpful to have that knowledge up your sleeve when you talk to your neighbour.

Guest
Martin McIntosh says:
7 December 2017

Our DAB radio in the kitchen on the other side of the house cuts out completely as soon as we switch on the LED spotlights about 15 metres away on the landing or in the upstairs bathroom. The same thing happens with a different make of DAB radio in the bedroom. I replaced 50 watt 12v Hologen MR16 ceiling spotlights in our upstairs bathroom and landing with AuraLED AL-MR16PRO-7W bulbs, recommended by a local retailer. They were the only ones I could find that worked with the existing 12v transformers without flickering or strobing. Lumilife MR16 spots from LED Hut do not interfere with the radio signals but flicker all the time. Unfortunately I had been using the Auraled lights for some months before we bought the DAB radios and realised there was a problem.

Guest
richard hart says:
8 December 2017

In reply mainly to Mike Fulton, I believed I had exactly his problem. After several cheapo LED bulbs, I put a Phillips 13W LED replacement where I used to have a standard BC 100w, in my bedside lamp. The lamp is on a 4ft chest, and 4ft from my old Sharp radio that is usually tuned to R4FM. Immediate low volume pink noise over the audio as soon as the light is switched on. The previous LED bulbs were worse.

So I thought of moving the room around. After a hour or so of preparation I was ready to test, moving the radio further from the bulb. As soon as I started to move the radio, reception became clear. Reception remained clear when the radio was on the chest 1ft from the lamp. After some fiddling, I am satisfied that the interference is coming from the proximity of the radio and the lamp mains leads. They both plug into a block below my bedside table, and how the cables cross each other as they leave the block seems to be critical.