Buck Converter for Parallel LED's

So I am trying to make a gift for someone that will include about 100 LEDs. These LEDs have a forward voltage of 1.8-2.2 ( I am going with 2V) and a max continuous forward current of 30mA. The LEDs:

http://www.ebay.com/itm/50-10mm-10000mcd-LED-Lamp-Ultra-Bright-Red-Light-DIY-New-/180763201504?pt=LH_DefaultDomain_0&hash=item2a16538fe0

Now, I want to be able to plug this sign into a wall so I have purchased an AC to DC power adapter that plugs in into a standard 120V AC outlet and supplies 12V with 2A of current. Here it is:
http://www.ebay.com/itm/261176168283

I know one way I could make this work is to have multiple series of 6 LEDs, as 6 LEDs in a series would then require 12V. However, it would make this project a LOT easier to have all the LEDs in a parallel circuit, so I can connect one whole side to the positive terminal and one whole side to the negative terminal. I wanted to know if I could do this: Plug the two wires (+ and -) going from the AC to DC adaptor into a Buck Converter set to 2V and wire it to all the LED's via one wire to a bus wire connected to all of the LEDs' negative terminals and same for the positive terminals. 

The converter I was looking at:
http://www.ebay.com/itm/DC-DC-Buck-Converter-Adjustable-Step-Down-Breadboard-Power-Module-1-25V-36V-5A-/321355701600?pt=LH_DefaultDomain_0&hash=item4ad24add60

Also, if I place the switch in between the AC to DC power adapter and the buck converter, the converter would only be on when the LED's are on, right? Lastly, would all the LEDs have the same brightness?

I know at 2V with 100 LEDs the output would need to be about 3A. Is it okay given that the power adapter supplies 2A but at a higher voltage? As in does the converter convert the electricity to a lower voltage but a higher current?

soulmouse (author) 3 years ago

I don't get why you say I should forget the idea. The LED's will be in a circle essentially, so if I can connect one bus wire to all the negative terminals on the outside of the circle and one to all the positive terminals on the inside it would be a LOT easier. I know about the 6 in a series but I'm just looking for an easier alternative. Is there any reason why the buck converter wouldn't work?

Never said it wouldn't work.

If all your doing is making a circle with these LEDs then go with the buck converter. But if that is all your doing you can purchase a string of LED pretty cheap. That would be much easier than wiring your one string.

You need to look for an online LED calc. Plug in the specs of the LEDs and the power source you want to use and it will give you the wiring and resistors needed for the circuit. In this case you will need several series strings made up of 6 LEDs. Then all those stings will be wired in parallel to the power source. In this kind of an array the LEDs will be drawing less than 1A from the power source.

Don't bother with the buck converter idea. Either way you go it's 100 LEDs your dealing with and the wiring will be a mess.