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Buckpucks in series on mains power

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mneary

New Member
Short answer: NO

To function in series, their current draw must be EXACTLY the same. This is impossible, not just because their loads might be different, but also because as a switching power supply its input current decreases as input voltage increases. (Their V/I curve looks like a negative resistance within their operating range.)

Second problem: Isolation between input and output isn't specified. This could place higher standoff potentials on the pucks that are nearer to the mains hot side. I'm guessing that if you wanted your LEDs to float at 240V you would hook them directly to the mains.

This is my opinion only; check with the factory. They might have a product that meets your needs.
 

hazey36

New Member
bummer,

sorry but i hate it when my theories don't work out.

just to clarify though, you weren't referencing the current vs voltage sheet in the link i posted were you? as this is related ti the optional dimming circuit that can be used with a potentiometer or similar.

thanks for the post though. definitely no way to do it???
 

jrz126

Active Member
How many LEDs are you trying to drive?

There are plenty of off-the-shelf drivers that will run right off the mains. And they are alot cheaper than those buck-pucks.
 

mneary

New Member
just to clarify though, you weren't referencing the current vs voltage sheet in the link i posted were you?
Nope. Buck converters just work like that.

For a constant power out, they take a relatively constant power in. So if their input voltage increases, they actually use less current. Just the opposite of a normal resistor (hence the term 'negative resistance') They would go crazy in series with one another.
 

hazey36

New Member
jr7126 - i'm looking to drive cree xp-g LED's at 1amp, 6-7 in series per buckpuck, up to 10 buckpucks.

that was the plan anyway...

mneary - that kinda sucks actually, so it wouldn't matter if it was ac or dc, it would be the same... crap.. lol
 
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