I have 32 3mm leds i want to light

Good evening,
I'm doing a project with my son, we want to put led on one of his favorite pictures.
We have 32 3mm leds. The specs
Forward Voltage : 2.0 - 2.2V;Max Continuous Forward Current : 20mA
How do I go about getting this lit, I'm assuming that they need to be wired in series. I just can't figure out how to power them.

Thanks in advance.

If you are in North America, I would get a power supply like this: http://www.digikey.com/product-detail/en/phihong-usa/PSM03A-120-R/993-1232-ND/4031883 and a handful of these: http://www.digikey.com/product-deta...ronics-inc/CF14JT180R/CF14JT180RCT-ND/1830332.

Then wire 4 LEDs in series with one resistor. Do that 8 times and connect them all across the power supply.

If you spent a few more bucks you could get a 24V supply, and put 8 LEDs in series on each of 4 resistors, but you'd need a different value. If you happen to have a supply kicking around, we can figure out a combination that would work for whatever voltage it is. Even as low as 5V would work, but you'd need 16 resistors.

Thank toy for the quick reply!


Can I use a iPad wall wart?

Probably. What does it say the output is?

Thank you for the help.

A 56 ohm resistor in series with two LEDs. Times 16.

would these work?

http://www.amazon.com/gp/product/B009XOP27A/?tag=cpf0b6-20

Yes.

So would these: http://www.digikey.com/product-detail/en/yageo/CFR-25JB-52-56R/56QBK-ND/2528. USPS shipping was under $3 last time I used it.

thanks,
so let me wrap my head around this.
I should solder 2 LEDs in series with this resistor on the positive leg>
repeat this 16 times, then take all the positives and solder that together and the same with the negatives minus the resistor?

What would you do in your professional opinion?

What I think you are saying is correct. But just to make sure we're both on the same page...

You will connect one end of each resistor to the + of your power supply. The other end of each resistor connects to the + side of an LED (the anode). The cathodes of this first row of LEDs connect to the anodes of the second row of LEDs. The cathodes of the second row all connect to the - side of your supply.