Running AC 12V lamps off DC?

Dec 16, 2010 2 Replies
C

Hi all,



I was given the task of lighting up the office fibre optic christmas tree.



I was given a 12VDC switch mode PSU to power it with as it's PSU had been lost.



It worked for a few hours, but when switched on next morning the bulb (10W 12V quartz looks a bit like a GU type but with pins rather than a bayonet arrangement) flashed and then died.



Also the motor for the coloured disk which was supposed to make the fibre optics change colour hadn't gone round at all (either day) which made me wonder if it's motor was designed for an AC input, and thet's what the original PSU had been



What does the team think? If the bulb had been designed for use on AC would DC shorten it's life significantly (be nice to know before I plug in a replacement)



Is the motor likely to turn if I feed it AC?



Assumming it was designed for AC, will feeding it DC have killed it?



TIA



Chris


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H

snipped-for-privacy@o2.co.uk expressed precisely :

The lamp would have been fine on either AC or DC, but the motor is a synchronos one and must be fed AC - so that may well have burnt out.

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G

The flash and die is more likely due to the lamp being knocked or moved when hot .... and / or , switch mode psu will supply much-o-big amps for a short time , so the switch on surge caused by the cold lamp would be much bigger than a transformer could supply and ripped the lamp apart

The motor - if there was -no- smell or smoke it probably will still work on a 12v ac supply

G..

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