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craigja

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When i moved into my house 17 years ago i fitted MR16 50w halogen lamps in the lounge, soon after i replaced these for 20w to save a bit of energy. Now that LED MR16 lamps seen to be finally making their presence, i am thinking about moving over to them.
The transformer i used was from CEF, i recon it was a CET 200va wire wound torodial ?? Which has been humming away under the floorboards for all these years..lol
My question is that if i decide to use 12v LED MR16 lamps on this transformer, will it actually save energy ? Or will the transformer just turn the unused energy into heat ? and not save any cash at all.
Ideally getting access to the transformer and removing it completely would be the best option as i can then use GU10 LED lamps just like my daughters room, but getting access is a bit of a job and i am looking for the quickest option... any ideas out there ? Cheers
 

telectrix

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LED lamps need sapecific LED drivers. if you fit to the present tranny, you'll probably get a shock to the wallet. best way forward is GU10 LEDs.
 
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craigja

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  • #3
i have read that old wire wounds transformers will work ok with LED's, and as long as the voltage from the teansformer does not go over 12.5v it should be fine ... although i totally agree about the GU10 LED's ... i already use them elsewhere in the house
 

telectrix

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they may well work. i've never tried them, but i would be wary of blowing half a dozen LED lamps out as an experiment.
 
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craigja

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Thanks for the advice ... Here is what i have read, but in no way saying its 100% true

There are three types of power supply that can be used with regular (halogen) MR16 lights. The first is a regulated power supply, comprising a transformer, rectifier, capacitor (to smooth the half-wave pulses) and an electronic voltage regulator. This provides a very smooth 12 volts DC, and will drive halogen or LED MR16s perfectly. It's also the most expensive kind, and is therefore not much used.

Another type of power supply is a regular transformer, made from primary and secondary wire windings around a magnetic core. This produces an unregulated 12 volts AC, which is fine for driving halogen bulbs and will produce good results with most LED bulbs. It's recommended to have an electrician measure the output voltage because if it is above 12.5 volts the life of the LED units will be greatly reduced.

The third type of power supply is an electronic transformer, which uses a high-power switching semiconductor to interrupt the mains voltage at a very high frequency. These are the ones most likely to give problems with LED bulbs. That's because they have been designed to work properly across a certain range of power loads. For example, the electronic transformer might be specified for a load range of "20 to 60 watts", which means that it will operate within its specification only when connected to a load which is somewhere within that range.

LED bulbs draw so little power that they won't reach the minimum wattage, and therefore the electronic transformer can't be depended on to operate within its specification. I have heard it said that provided you can load the transformer with at least five watts, it's likely to work, but it's never a good idea to operate a device outside of its specification.

Some LED bulbs draw not much more than one watt, but some lighting transformers supply more than one socket. This makes a workaround possible: keep one halogen bulb in each lighting circuit, with the remainder of the bulbs replaced by LED bulbs. I feel this would usually be undesirable on aesthetic grounds, due to the different quality and quantity of light emitted by halogen and LED bulbs.
 

telectrix

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you could always fit a voltage regulator to the tranny, make sure it doesn't rise above 12V. i still prefer GU10s though.
 
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craigja

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  • #7
you could always fit a voltage regulator to the tranny, make sure it doesn't rise above 12V. i still prefer GU10s though.
True ... i have seen them for about £5 each.
 
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craigja

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craigja

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This regulator circuit is perfect for LED lighting applications using 12V LED Spotlights. These bulbs have a working voltage of 10.5-13.5 Volts, so if they are directly connected to a 12V-rated lead acid battery, the bulbs could easily be damaged by the 13.5V+ voltage of a fully charged or under-charge battery.

If a switch is to be used - e.g. for lighting - it should be connected into the circuit before the regulator so that the regulator does not draw any power from the battery except for when needed. Similarly if using a fuse, it should be fitted into the positive line connecting the battery to the regulator and located close to the battery.

[h=2]Current Limitations[/h]The 0.7 Amp current limit on this regulator circuit corresponds to powering up to seven 1 Watt LED spotlight bulbs. The onboard heatsinking keeps the regulator cool under load with up to 4 to 5 of our* 1.5W spotlight bulbs when powered from a 12.5-16V (typical lead acid battery) source.
* Other bulbs may use more power and therefore current than labelled. If you have bulbs from another supplier we recommend you test their power consumption.
 
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craigja

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  • #11
My last 2 posts are still waiting for mod approval
 

telectrix

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only problem is those regulators require a d.c. input, so you'd need a rectifier circuit on the sec. of the tranny.
 
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craigja

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  • #13
Sorry my mistake .. you are correct. Its a good job i never ordered 4 of them ! I only need 2 now for other ideas around the house. Thanks very much for your advice. :39:
 
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