Noisy 13.8v power supply

[michaelmorris]

A few weeks ago I bought a 5A 13.8V power supply from the Astroboot sale at Kelling Heath Star Party. It was as cheap as chips at just £5. Unfortunately, I think I've found out why it was only £5.

After about 10-15 minutes of drawing a load (dew heaters) it starts to make a buzzing sound. The more dew heaters I plug in to the dew heater controller fed from the power supply, the noisy it is.

Any ideas?

[steppenwolf]

Is the PSU a 'switch mode' type? A clue is the weight, if it is lightweight, it will be a switch mode as these only have a small transformer.

Buzzing from PSUs is normally caused by the laminations in the transformer core of non switch mode types having separated slightly and, although intrusive, are not normally a cause for concern. If you have a switch mode type I would be a little more concerned. You may feel it would be better to replace it and buy new and this article on my website tells you about a good value for money PSU readily available:-

http://home2.btconnect.com/astro-site/ac_psu_for_skywatcher_mounts.htm

[michaelmorris]

Is the PSU a 'switch mode' type? A clue is the weight, if it is lightweight, it will be a switch mode as these only have a small transformer.

Buzzing from PSUs is normally caused by the laminations in the transformer core of non switch mode types having separated slightly and, although intrusive, are not normally a cause for concern. If you have a switch mode type I would be a little more concerned. You may feel it would be better to replace it and buy new and this article on my website tells you about a good value for money PSU readily available:-

http://home2.btconnect.com/astro-site/ac_psu_for_skywatcher_mounts.htm

Thanks for the advice. It's a non-switch mode type. I've now had it apart and I'm pretty certain it's the transformer that is making the noise. The noise is pretty blumming awful, especially on a quiet night, so I'll ditch it and just put the purchase down to experience.

Thanks for the advice on the Halfords unit. I've bought one today and it seems to be ideal. An absolute steal at only £12.99; that's pretty much half the price of any comparable unit and a real find. I'lll post a link to the Halfords unit on the 'Heads Up' section.

[steppenwolf]

Thanks for the advice on the Halfords unit.

My pleasure - I'm very pleased with mine!