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Matt_Edwards
11-28-2010, 07:51 PM
I know it is late in the year, but I needed to add some White LEDs to the Star topper on my mega tree.
Kmart has 250 LEDs with for $19. The Transformer is a SMPS with a built in multifunction controller.

Construction looks OK but there is not enough lay on the wires. My son and I went out on the road with our trusty cordless drill and spun the end LED for some time. That fixed that issue!

The packaging says the LED supply voltage is 31Vdc. I connected them to my variable PS and set it to 31v. The LEDs glow but are far from acceptable. The current draw is low too (I will edit it in tonight)
so I wound the volts up to 32.5 volts and the current draw went to 120mA.

Now for the confusing bit. The packaging says they are 250 LEDs. the strings are wired in 10 LEDs pre string with two strings wired in staggered format per section. That is 20 LEDs per section. 250 / 20 = 12 1/2 sections!!! What the heck. Hopefully I will answer this confusion tonight when I add resistors so they can be driven with 36v.

BTW driving all both parallel section with ~200 mA gives plenty of brightness.

My Star is a 3x 5 point stars set at 60degree - pretty standard stuff. Tonight we paint the star.

DIY Guy
11-28-2010, 08:13 PM
Is this the store brand? The ones on the plastic reel?

EDIT: woops, I see this is down under :) No wonder I couldn't figure out what you were talking about.. was just there today.. in the US :)