The MR16 lamp was first sold in 1965. Emmett H. Wiley of General Electric (USA) was awarded patent #3,314,331 for a miniature reflector lamp in 1967. As to when they arrived in the UK not sure. But the early lamps had tordonal transformers, however these were hard to dim, the inrush would normally cause dimmer switch to fail, also any variation in supply was reflected with output of transformer, so although the transformer extended the life over 230 volt lamps because the element was thicker the electronic replacement also regulated the output, and that is very important with a quartz lamp, run too hot and they fail as expected, but also run too cold and the quartz goes black and they fail and in theory should not be connected to a dimmer.
However the power supplies were made so they were able to dim the phase chopping of the dimmer switch was read as an instruction to dim by the power supply, but the new power supply had a problem modulating the pulse width had a limit and it would not control with low output, with 10 x 10W lamps on a single power supply the first 6 lamps could fail one by one without a problem, but as the remaining 4 failed as some point it would shut down, which left one guessing which lamps needed changing.
Latter models were able to control 0 - 105 VA for example however there was a second problem, the output was around 50 kHz which means often the supply leads between power supply and lamp are limited to 2 meters or less.
As the LED lamps came out some were designed for 50 Hz, and some for ripple free DC, and some did not care as long as 12 volt, some are marked 50 Hz and I have never bought DC versions, but would expect to find them marked 10 ~ 30 volt as in the advert, but many don't even have the voltage marked never mind AC or DC. I am sure most will work with a 0 to whatever switch mode power supply, but we don't know until we try them.
I fitted 4 MR16 pods with G5.3 holders in my bathroom powered from a tordonal transformer, they were not very good far too bright but once fitted to remove would leave a hole, so when I saw G5.3 MR16 lamps in Pound World even if only 0.58W I got 4 as they looked better than the blown quartz lamps, they were the only LED lamps I have bought which have failed, I blamed it on voltage spikes, and when Lidi did some 3 Watt I think marked clearly 50 Hz I replaced the failed lamps with second batch of LED's and they are still working fine.
Else where in the house all GU10 however easy when starting with GU10 one takes an earth to each lamp even if not required, but G5.3 often have no earth, so really one needs to rewire with an earth even if not used. Not sure I would bother with class II fittings, but you in theory should have an earth available.
So here are the options:-
1) Remove dimmer switches and swap transformers for tordonal type and keep as 12 volt.
2) Fit 0 - whatever electronic transformers as they are called and cross your fingers it works OK, this includes DC so called drivers (not really drivers you need fixed voltage of 12 volt true drivers have fixed current and voltage varies.)
3) Swap cable and lamps to GU10 and use direct mains.
Method 3 and the GU10 will work, the others your crossing your fingers and hopping, with mine the first LED G5.3 lamps lasted 6 months they did not fail straight away, not that I would have taken back at £1 each, but if changing 10 at even just £4 each that is still £40 worth of lights which may fail just 6 months down the line, may be worth it if tordonal transformer already fitted but not if you need to buy new.
