Hello. I'm a total newbie to creating my own circuits. I've done a lot of soldering and have been able to follow instructions for wiring up my own type of stuff but i've never designed a circuit and so i'm still learning all the basics. What i'm trying to build is a small, battery and/or AC/DC powered device which is nothing more than a IR LED lamp. It will have 3-5 IR LEDs that will constantly be on. The device will have a switch to turn it on or off and a little red LED to indicate its power state (since I can't see in infrared). Now I was chatting with some people on IRC and they told me I should use a current source. So i've been reading up on it and it seems like a good idea, especially if i'm using batteries. So my question is... how do I create a current source with what I want? I would like to be able to power this whole thing with maybe 1 or 2 AA batteries (as small as possible) but also have a plug for AC/DC adapter for an outlet. I am not sure how to build a current source. All I figure is grab the LEDs, solder them together with wire and attach to battery and switch =) (like I said, i'm a newbie). Can anyone help me with this? It would be greatly appreciated!! Thank you very much.

 

Hi,

Any battery is a current source. IR LED's take lots of current to run - between 20 and 50 ma. That's a bit much for AA's.

Look at our material here - http://www.allaboutcircuits.com/vol_3/chpt_3/12.html - and come back if you have more questions.