AC to DC Power Transformer? 1

[alokwww]

Hi, I was looking for some kind of electrical or electrical engineering forum but couldn't find any and I watch you guys a lot and know you're pretty knowledgeable with this stuff.

Basically, what I'm trying to do is power many LEDs.
The specs on these are: 3.3VDC Forward, 5VD Reverse, 0.02 Amps.

I need to figure out a way to connect as many LEDs as possible to a 120VAC source.

My first though was just to go find a DC Power Adapter, but the largest I found was 12V, which to my calculations(which could be wrong, seeing as I have little experience with this kind of stuff) would only give me 3 LEDs.

12VDC Power Source - 3.3V LED - 3.3V LED - 3.3V LED = 2.1V
2.1VDC Left / 0.02 Amps = 105 Ohms

So according to my calculations I would use a 12V DC adapter and an 105 Ohm Resistor to power 3 LEDs. 3 LEDs is just not enough. Am I doing this wrong? Do I have other options? Can I get a DC Power adapter with stronger output for cheap (we are a VERRRYY low budget theatre and basically all of this stuff I'll end up donating)?

Thanks for any help you may be willing to offer me.
-Alok

 

[franklin97355]

You are looking at this all wrong. Go back and read up on basic electricity. The voltage needed is 3.3v but each led doesn't use up the voltage you need to limit the current each led gets or it will blow but you can drive as many leds as the current the PS can supply. You should be able to drive approx 50 from a 1 amp supply (but I wouldn't push it that close)

 

[franklin97355]

You might also try

http://www.eng-tips.com

 

[smah]

Yes, you're thinking series instead of parallel.

 

[alokwww]

Awesome, I think I got it. Thanks to everyone who replied, especially Franklin!

Thanks Again!
-Alok