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12V LED downlights from halogen transformers

2357 Views 2 Replies 3 Participants Last post by  Electric_Light
Hello all,

Many halogen transformers don't work with LED bulb replacements because there is a minimum power requirement for the switchmode transformer to work properly. Therefore, I would think that if I wired 4 or 5 LED globes in parallel to a 60VA transformer then it should work. Is this correct?

I have looked at LED specific 12V drivers and they work as current drivers and therefore require multiple LEDs to be wired in series. Is this the same for the halogen transformers, or do they work as constant voltage outputs?

Your advice is greatly appreciated.

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· Administrator
Retired EC
24,909 Posts
I would not mess with a listed fixture. If the fixture is 12V and not rated for LED I don't know how you could configure it to work as the LED's use a driver to communicate much the way a printer on the pc is used to recognize the printer. Therefore modification of the fixture may be necessary. That being the case you have nullified it's listing and that is a no-no here in the states.

I have read that it is inefficient NOT to wire LED's in series. Here is a resistor calculator needed for LED's

Sorry I can't help any further as I really don't understand the nuances involved with LED. I also don't know why some tranies won't work with a minimum wattage but I have seen it make the lights blink and act weird.

· Light Emitting Decoration
1,323 Posts
LED chips require current regulated power supply, but there are some LED light modules that are designed to be used with constant voltage power source.

Current source LED modules are often used in series-parallel arrangements, for example, 1000mA driver used to drive three strings of four 350mA LEDs in series.

Electronic transformers put out high frequency output at 10s of thousands of Hz.
They're basically electronic ballasts configured to operate as constant voltage rather than constant current.

I would just go with 12v rated ones and replace the transformer with a 12v LED spply.
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