Buzzing Transformer

[Castle-Man]

One of my C912 Transformers buzzes audibly when plugged into the mains.  Both on and off load.  

It seems to be working fine and the R965 that it is plugged into controlls trains forwards and backwards exactly as expected.

Should I worry about it?

[Rog RJ]

Nothing to worry about.  Most transformers buzz, some rather more than others.  It can be due to loose windings or laminations of the transformer core.

[Yelrow]

Castle man. If you are concerned, get it checked by an electrician, or shop. I have more than   one that  buzzes. The older Jouefs, mostly do, but my guy says they are fine. My H&M,  s, occasionally, hum gently. At least  i know they are on.  . john

[Castle-Man]

Thanks for the replies.  Certainly used to the older transformers buzzing.  

However the more modern ones for laptops, computer equipment, shavers etc. many of which may be switching transformers tend to be silent.  As the C912 looks like one of those and plugs into the R965 I though that I would ask.  Especially as my other one does not.

  

[morairamike]

 Slightly off topic but my shower cubicle, like most these days, has a 12V light and extractor fan. The transformer for this is mounted in a small plastic box in the ceiling. One day there was this very bad vibration coming from the ceiling above the cubicle whem the light and fan were on. So I braved the loft insulation and got up there and removed the box so I could replace it. When I opened it I found that the small screws securing the transformer to the box were loose and that was the cause of the vibration. Tighten screws and refitted, no more noise or vibration.

[Chrissaf]

However the more modern ones for laptops, computer equipment, shavers etc. Many of which may be switching power supplies tend to be silent.

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Modern switch mode power supplies aren't based on Transformers for reducing the mains voltage. Therefore they tend to be silent in running, although cheap or poorly designed ones may have a very high frequency whine emanating from them under load. Switch mode technology is becoming so cheap (cheaper than the cost of a transformer) the technology is finding its way into most consumer products.

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The low frequency 50Hz hum that older power supplies can give off, as others have reported on here, can be caused by transformers ageing and the metal laminations of the transformer construction becoming de-bonded. That and/or loose mounting screws and fixings. Transformers by their very nature generate magnetic fields at 50 hz frequency (UK mains frequency). These magnetic fields over time exert significant mechanical forces on the metallic components used in the transformer construction. High power transformers will generate hum as normal just due to the power that they are passing. ARC welders for example. Electric company street located sub-stations can often be heard to give off a hum as one walks past them.

[Castle-Man]

However the more modern ones for laptops, computer equipment, shavers etc. Many of which may be switching power supplies tend to be silent.

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Modern switch mode power supplies aren't based on Transformers for reducing the mains voltage. Therefore they tend to be silent in running, although cheap or poorly designed ones may have a very high frequency whine emanating from them under load. Switch mode technology is becoming so cheap (cheaper than the cost of a transformer) the technology is finding its way into most consumer products.

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The low frequency 50Hz hum that older power supplies can give off, as others have reported on here, can be caused by transformers ageing and the metal laminations of the transformer construction becoming de-bonded. That and/or loose mounting screws and fixings. Transformers by their very nature generate magnetic fields at 50 hz frequency (UK mains frequency). These magnetic fields over time exert significant mechanical forces on the metallic components used in the transformer construction. High power transformers will generate hum as normal just due to the power that they are passing. ARC welders for example. Electric company street located sub-stations can often be heard to give off a hum as one walks past them.

What I am not sure though is whether the Hornby C912 as used with the R965 controller and also by Scalextric at that time is a proper transformer or a switching type.  Any idea?

[Chrissaf]

The input into a R965 is 17.5 volts AC. Therefore the output of the C912 is also 17.5 volts AC. Switch mode power supplies typically provide highly regulated DC outputs. Therefore, the C912 is unlikely to be a switch mode power pack as it has an unregulated AC output. Apart from which, the design of the C912 dates back to a period that predates the common use of switch mode power supplies as cheap power packs.

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It is almost certainly a basic transformer to reduce mains input AC down to 17.5 volts AC and nothing more sophisticated than that.

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PS - could I humbly advise not to use the 'white arrow in blue box' button to make a reply. This is not a 'Reply to this Post' button. It is always best to use the 'Reply Text Box' at the bottom of the page and click the Green 'Reply' button. There is no need to always reproduce the whole of the previous post as a 'quote' in the yellow text box, particularly when replying to one of my longer replies.

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If there is a particular comment you want to quote. Then paste it into the reply and convert it to a yellow quote box using the 66 icon (third one in from the left). As I have done with this example paragraph.

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[Castle-Man]

Thanks.  Reply point noted.  Used to using that reply on forums as it allows people to know who's post the reply is to otherwise it gets messy trying to work out what relates to what.  I understand though that if it  quotes the post it can becomes long winded.  Maybe it would be better to remove the function from the board completely.  Eitherway I will ignore it in future.

On the subject of the C912 if it is a real transformer then the fact that it is humming is not completely strange.  What is more strange is that others do not but I suppose that age and usage comes into it.