# Why are my MR16 LED bulbs turning on and off every 3 sec.



## B W E (May 1, 2011)

amh said:


> I custom-made a lamp for a customer that uses 12 4w mr16 high quality bulbs he bought.
> 
> I bought an LED driver which should be ideal for the job.: http://www.amazon.com/gp/product/B003WJ3T8G/ref=oh_o00_s00_i00_details
> 
> ...


Are you using a digital dimmer by any chance?


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## french connection!! (Dec 13, 2007)

how far apart the bulbs are and how far the transformer is from the bulbs ? try with 10 bulbs


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## HARRY304E (Sep 15, 2010)

amh said:


> I custom-made a lamp for a customer that uses 12 4w mr16 high quality bulbs he bought.
> 
> I bought an LED driver which should be ideal for the job.: http://www.amazon.com/gp/product/B003WJ3T8G/ref=oh_o00_s00_i00_details
> 
> ...


Did you check the voltage of the lamps?


They make a line voltage MR-16 and then you would just need a dimmer switch rated for led lamps.

http://www.homedepot.com/buy/lighti...smart/mr16-led-20w-equivalent-bulb-39646.html

http://www.homedepot.com/buy/electr...way-dimmable-cfl-led-dimmer-white-192238.html


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## amh (Apr 6, 2012)

I already tried with fewer bulbs, still the same issue.

@french connection!! The bulbs that are the furthest away are about 5 feet away.

@B W E and @HARRY304E No dimmer, but the connection may be less than perfect, thus producing some resistance. Double checked, voltage of bulbs is 12v


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## french connection!! (Dec 13, 2007)

must be the thermal cut off protection built in that's screw up .


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## BBQ (Nov 16, 2010)

amh said:


> I custom-made a lamp for a customer that uses 12 4w mr16 high quality bulbs he bought.
> 
> I bought an LED driver which should be ideal for the job.: http://www.amazon.com/gp/product/B003WJ3T8G/ref=oh_o00_s00_i00_details
> 
> ...


Why do you think an LED driver is ideal for this?

An LED driver is ideal for driving LEDs

How about a low voltage lighting transformer? 

http://www.amazon.com/s/ref=nb_sb_s...former&sprefix=low+voltage+li,electronics,179


Beyond that ....



> *ARTICLE 410
> Luminaires, Lampholders, and Lamps
> 
> I. General
> ...





> *410.6 Listing Required.* All luminaires and lampholders
> shall be listed.





> *Luminaire.* A complete lighting unit consisting of a light
> source such as a lamp or lamps, together with the parts
> designed to position the light source and connect it to the
> power supply. It may also include parts to protect the light
> ...


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## wildleg (Apr 12, 2009)

your transformer is kicking out on overload. did you measure the amperage ? try driving 1, repeat 1 bulb.


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## Electric_Light (Apr 6, 2010)

What are the spec and requirements of the each lamp?

Some LEDs are 12v, 24v or constant current 350mA and such.
If you pair LEDs that require a constant current source and wired in series with voltage source and wire across the power supply, it will "short" the power supply and repeatedly trip the overload.

If *all* bulbs are flashing every 3 seconds, then the power supply is cycling and most likely for the reason I just mentioned.

Remove one of the leads from the power supply going to the string and splice in a 12v car brake lamp in series. I bet they'll light up and remain lit. No, this is not meant to be for a permanent install. Just for testing.


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## Southeast Power (Jan 18, 2009)

Install one 12 volt low wattage incandescent lamp in the circuit


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## amh (Apr 6, 2012)

*Figured it out*

For some reason the transformer / LED driver wasn't able to handle more than 2 bulbs at once even though watt-wise it is supposed to. Anyhow, bought a few more, and installed 1 driver per pair of bulbs, now it works perfectly:


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## amh (Apr 6, 2012)

Aren't LED drivers basically ballasts for LEDs? As far as I understand they prolong the life of the LED bulb by better regulating voltage variations, and along with that, they decrease micro flicker effect.


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## chrisfnl (Sep 13, 2010)

That's a swanky looking light.

"Ballasts for LED" is a terrible description... power supply for LEDs, yes.

They can be a constant current supply or a constant voltage supply. All that's in the driver you used should be a transformer, a rectifier, and a filter.

I'm a little confused, were the bulbs LED bulbs? If not, were they rated for 12v operation?

Also, I'm not seeing any underwriters markings on the driver, and I don't read chinese. Maybe that's why the manufacturer seems to be "Junk".


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## HARRY304E (Sep 15, 2010)

amh said:


> For some reason the transformer / LED driver wasn't able to handle more than 2 bulbs at once even though watt-wise it is supposed to. Anyhow, bought a few more, and installed 1 driver per pair of bulbs, now it works perfectly:


I'll bet that was fun..:laughing:


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## electricmanscott (Feb 11, 2010)

Inspection fail


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## BBQ (Nov 16, 2010)

amh said:


> Aren't LED drivers basically ballasts for LEDs?


Yes, exactly that.


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## BBQ (Nov 16, 2010)

chrisfnl said:


> That's a swanky looking light.
> 
> "Ballasts for LED" is a terrible description... power supply for LEDs, yes.
> 
> They can be a constant current supply or a constant voltage supply. All that's in the driver you used should be a transformer, a rectifier, and a filter.


Incorrect, an LED driver varies the voltage like a ballast.





chrisfnl said:


> .
> 
> I'm a little confused, were the bulbs LED bulbs? If not, were they rated for 12v operation?



He is using 12 volt incandescent lamps, he should have used a transformer.

But there is still a listing issue resulting in a code violation.


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## chrisfnl (Sep 13, 2010)

BBQ said:


> Incorrect, an LED driver varies the voltage like a ballast.


If it's a constant current supply.

Unless there's somthing written in chinese that I'm missing, the driver he showed us was a constant voltage supply.

Even if it were a current supply driver, it's still not "like a ballast", a ballast supplies a high starting voltage to strike the arc, then drops and stabilizes to maintain the arc. 

An LED driver should maintain a constant, whether that constant the supplied current or the supplied voltage.

I guess you could say it's like a ballast in that you've got to have one to make the lights work, but that's like saying a starter motoris the ballast for my truck.



> But there is still a listing issue resulting in a code violation.


I like the brandname... "Junke"


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## Vintage Sounds (Oct 23, 2009)

If you are using LED MR16 replacements, those lamps are expecting 12v AC. They internally rectify, filter and step down the voltage to whatever the LED likes. If the power reaching it is already DC then you are going to lose some voltage through the process that was intended to step down rectified AC. I could be wrong but I think this is why your lamps are unhappy.


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## Davethewave (Jan 6, 2012)

wildleg said:


> your transformer is kicking out on overload. did you measure the amperage ? try driving 1, repeat 1 bulb.


LED in rush current can be calculated as 5 time wattage of lamp.


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