My daughter wants to make a duck in grass using colored LEDs for her 5th grade electrical project. We have 6 green, 4 red, 10 yellow. These are all the same (intensity 50-80 mcd; wavelength 590nm; FW current 20 mA; FW supply 1.9V typical 2.4V max). We have a spst micromini toggle switch "rated 3A at 125VAC" and some 22 gauge wire. I've done these projects in the past (eventually having success, the switch being the most frustrating piece of all since I don't know which is +/-) but the LED is new territory. I've read a LOT of posts. I know how to do series, parallel, the difference, etc. (not much more...) The project dimensions will be about 12" x 12". I have several questions.
1. Can I mount this whole thing on a gift box lid. Kid wants to paint background, duck, etc. We were planning to poke the LEDs through the lid and wire / tape on the back.
2. If we connect this in *series* I'll need 38-48V, right? That is five (5) 9V batteries. That sounds like a lot. Then I'd need an 860 ohm resistor? Clearly this is new territory.
3. Or do I do this whole thing in parallel. But I read in another post that I should put a resistor in front of each LED. That is TWENTY resistors. A lot for a tiny 5th grade project.
Bottom line question - what is the easiest, fastest way to accomplish wiring these 20 different LEDs (so it looks like a duck in grass) without burning them all out? Also, with this switch, is the "longer" lead the positive? I read another post about someone with 32 LEDs only needing a single 9V battery so clearly I'm missing something.
I really have searched and searched. I'd appreciate some EASY (i.e., "eHOW") help. Had a basic EE course in college but was a long time ago. Thanks.
1. Can I mount this whole thing on a gift box lid. Kid wants to paint background, duck, etc. We were planning to poke the LEDs through the lid and wire / tape on the back.
2. If we connect this in *series* I'll need 38-48V, right? That is five (5) 9V batteries. That sounds like a lot. Then I'd need an 860 ohm resistor? Clearly this is new territory.
3. Or do I do this whole thing in parallel. But I read in another post that I should put a resistor in front of each LED. That is TWENTY resistors. A lot for a tiny 5th grade project.
Bottom line question - what is the easiest, fastest way to accomplish wiring these 20 different LEDs (so it looks like a duck in grass) without burning them all out? Also, with this switch, is the "longer" lead the positive? I read another post about someone with 32 LEDs only needing a single 9V battery so clearly I'm missing something.
I really have searched and searched. I'd appreciate some EASY (i.e., "eHOW") help. Had a basic EE course in college but was a long time ago. Thanks.