LED lighting

[bxman]

Having just bought a 12v   24 smd  led module/bulb.

It was sold as a DC device,   it has a bi-pin fitting  and has no polarity markings

It works regardless of polarity.  So am I correct in thinking it has a built in diode bridge, in which case can I run it from an AC supply?

Thanks.

[pdf27]

DC = 12V
AC = 230V

If nothing else plugging it in will result in a very bright light (although a loud bang and the escape of magic smoke is much more likely)! Without smoothing capacitors it may well act as a 50Hz strobe as well.
The main bit I'd be concerned about though is earthing the surface - the requirements for 12V are much, much weaker than for 230V and **may** not be enough to stop the surface becoming live.

So if you do try this, make sure you don't do it anywhere fire would be an issue, switch it remotely and stand well back!

[bxman]

Sorry  I was thinking of a 9-12 volt ac supply

[pdf27]

OK, in that case the only risk will be strobing - which is likely to adversely affect the life of the bulb.

[billt]

Nonsense. Switching LEDs is a standard technique for dimming. A bit of 100hz is not going to affect the life at all. You might be able to see the flicker occasionally though.

Presumably its an MR16 bulb, if so it's intended to replace a standard tungsten bulb and will work fine from a suitable A.C. supply.

[pdf27]

Dimmable ones will have a smoothing capacitor across the rectified lines - if it has that then yes it'll be absolutely fine. If not then the life will be affected - not all LED bulbs are dimmable after all...

[bxman]

Thanks Folks
Still working after  trial
                    63mA on 12.4v dc.
                    49mA on  10v ac
looks to be usable light level.
sourced

http://www.ebay.co.uk/itm/320724996100?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2648

I will be having another attempt at persuading vender to give me a combined postage on 10.