I have just replaced a couple of halogen G4 bulbs in my cooker hood with LED versions. It works fine. However there is a slight noise now - I guess from the power supply. Is it being under-run? Does it matter? What causes the noise.
What sort of noise is it exactly? I mean is it a buzz, a whine or something else?
Do you know if the leds are el cheapo half mains cycle ones or full wave rectified ones? Brian
John formulated the question :
PSU is not sufficiently heavily loaded, which has changed its frequency, making it more audible.
"Brian Gaff \(Sofa 2\)" snipped-for-privacy@blueyonder.co.uk> wrote in news:qt51el$ge0 $ snipped-for-privacy@news.albasani.net:
slightly fizzing buzz. I don't know if they are half or full wave.
These do not normally make a noise though. Has the person checked the voltage is actually what its supposed to be. If it is the psu, and its not one of those sealed up potted ones one might be able to open it and see what is causing the noise. These must be capable of being run unloaded since ordinary filaments and halogen bulbs could easily end up all open circuit with no light, so removing the lights and listening is probably a good plan. If the noise is not there then then I'd suggest it as something to do with the kind of load the leds present, or is coming form one of them. Its a basic process of elimination. Brian
"Brian Gaff \(Sofa 2\)" snipped-for-privacy@blueyonder.co.uk> wrote in news:qt7cni$1s5$ snipped-for-privacy@news.albasani.net:
Thanks Brian - food for thought. At least no-one has warned that there may be a risk.
ALL my LED lamps buzz to some extent.
12V Halogen power supplies are often sold as "transformers" but are actually switched mode power supplies (SMPSU) with an AC (un rectified, un smoothed) high frequency output directly from the SMPSU output transformer complete with spikes all over the place which Halogen lamps are quite happy with but which LED lamps really don't like and which often causes premature LED failure. The power supply also finds the low load to be unsuitable. They are not usually considered to be suitable for use with LED's.
The old halogen PSU doesn't like being faced with the much lower LED current load. It probably isn't regulating properly and may well be generating RF interference as well as audio noises. Either swap the PSU for one more suitable or put one of the halogen bulbs back in the hood.
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