by ericmark »
Fri Mar 04, 2016 2:29 pm
Most of the power supplies for the 50W quartz halogen are pulse width modulated or switch mode two names for same thing. As a result they have both a minimum and maximum so swapping to LED will likely mean your drawing below the minimum rating. Also LED stands for light emitting diode and if you combine diodes and inductance together at a high frequency it can turn into a transmitter. If the transformers are the old heavy type toroidal transformers then likely you can simply swap, but with the lighter smaller "Electronic transformers" which are not really transformers then chances are you will have problems. You could remove some of the electronic transformers and power 4 lamps instead of one lamp of each and it may work. But also it can still cause problems.
The whole idea of the 12 volt quartz halogen was you have a thicker element in the bulb and a very precise voltage so the quartz envelope is held at a precise temperature. With LED there is really no advantage in using extra low voltage the low voltage (230v) work a lot better. So in the main it is better to swap the MR16 G5.5 lamp for a MR16 GU10 lamp and move to 230 volt.
If the LED bulb cost 50p then the idea of try it would be valid, but at £4 each you clearly want it to work. So in real terms either swap to 12 volt DC power supplies often called drivers although not really a driver as a true driver is fixed current not fixed voltage and you want fixed voltage. Or move to GU10 type and swap to 230 volt and do away with all the transformers. The latter is the better idea and cheapest but more work to convert wiring to 230 volt.
Also consider the difference in angles of the LED to Quartz halogen. The MR16 stands for multifaceted reflector at 16/8 of an inch, not a clue why not called 2 inch. These reflectors create the spot of light often aimed at a white surface which then gives a shadow free lighting to the room. Often angled to bounce light off the walls. Unfortunately some people have not realised this and fit them shining off a dark floor and whole room looks like a planetarium. With the LED there is often no reflector so really are not MR16 lamps, the LED does however naturally have a beam of light, but often not with the hard cut off point of the old halogen seeing a 25~35 is common where most of the light is in 25 degrees but some also spreads out to 35 degrees. Using one of these to replace a 60 degrees halogen will give a much narrower beam of light, reflected from a white wall still OK but against a dark floor really not what you want.
I saw one guy who has used GU10 to E14 adaptors and fitted candle bulbs in the holders to get the spread of light. If you are changing to GU10 then think are recessed lamps the best option anyway? Since LED does not get very hot you can get lamps which are surface mount and they may do a better job.
Google "surface mount LED lamps" then click on images and look at the options most will cover the existing hole many are a complete lamps the LED is not renewable when in 10 years time it falls then fit a new lamp, Although rated at 30,000 hours I expect most will exceed that time, I would not be surprised if double that time.
You may also want to look at 2D lamps, these are fluorescent lamps often 12 inch round or square which are nearly as efficient as LED and also surface mount.
