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LED drivers and power supply

Dangit

May 27, 2011
1
Joined
May 27, 2011
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1
Hi, I'm new here, and this is my first post...

Anyways, I've been wiring up some strings of LEDs, and I usually power them using a buckpuck and a regulated ac/dc adapter, and everything works fine.

One of my adapters passed away the other day, and the local electronics shop didn't have anymore, and can't get any. It was a 30volt, 800mA piece. I had been using these with buckpucks to run 6 and even 7 long strings of old Luxeon 3's.

Now I need to get (a few) power supplies/adapters. I know that I have to use either regulated or switching power supplies with the buckpuck, which has a limit of 32volts input.

First question: Are the adapters marked "120 - 240" (usable for range of voltages) considered 'switching adapters?"

Also, I tried using a 12volt 2.5amp apdapter, despite the fact that it would be putting out 30volts, the LEDs burn much dimmer. I did even try a 24volt 1000mA "regular" (not switching, not regulated) adapter that tested at under 31volts, and the LEDs seemed to burn TOO bright.

the 12volt 2.5 Amp ran the LEDs at about 2V forward voltage. Dim.
the 30volt 800mA ran the LEDs around 2.8 forward voltage (closest to desired).
the 24 volt 1000mA ran the leds at 3volts forward, which was too much, too hot.
The buckpuck is a 1000mA model.

Second question: What accounts for the differences?

I'll admit, I do not know so much about electronics. My knowlege is pretty much limited to the electronic experience in a first year undergrad course in physics.
Thanks in advance.
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,510
Joined
Jan 21, 2010
Messages
25,510
Your first problem is that you misunderstand LEDs. They require a current source, not a voltage source.

There is a sticky here that should help you get (and understand) the answers to your questions.
 
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