Hello I just found your community through Google.

I am total new to all this have very little knowledge, but I am learning on a regular bases.

I am helping out my kid to assemble a led array which has 9 5mm Blue Led

Led label reads as follow:

Iv= 13,000
Vf= 3.2-3.6
forward current = 20mA

I have found this

Can I run this circuit with Laptop Charge with the following specifications

Output= 19v 3.42A 65W

Please your help needed

Thank you

 

That should work. The only thing that might trip you up is that many power supplies along the lines of laptop chargers, will only work properly with a minimum load considerably in excess of 60mA. The one you have may or may not fall into that category. Even if it doesn't, the actual voltage might be considerably higher than 19V with such a light load (these are not intended to be tightly regulated supplies - that isn't necessary for the role they play). I would check the voltage with nothing plugged into it and see if it is anywhere close to 19V. Then, if it is, measure the voltage after hooking up your LED array.

You should be okay with 1/4 watt resistors. Use 1/2 watt if you can get them, but 1/4 W are much more plentiful and usually quite a bit cheaper.

BTW: What is it that you are using. Is this some kind of computer-based teach-yourself-electronics program that gives you these wizards to work out the details of an experiment that you then actually build and test? If so, I'd love to find out more about it.

Good luck!

 

Thank you for the fast reply, the image that you see is from
this site http://led.linear1.org/led.wiz, the project is for the camp kids to start learning about led's and resistors the resistors we got from freind we know the ohm but how we tell if they are 1/4 or 1/2 watt.

Thank you