7 Color Light Pen





Introduction: 7 Color Light Pen

This is my first instructable in a while. I've been busy busy busy with all sorts of things, some of which probably would have made good instructables, but few of which I documented very thoroughly. This instructable has been floating around half completed for a long time, and I figured it was time to just bite the bullet and post it.

I owe a debt to unklstuart for this instructable, which inspired me. I thought of making some of these light pens a while ago, but I am unfortunately not much of an artist. Still, the pens were awesome and I thought I'd like to have a set, if just to play around with. However, my camera only takes a maximum of 16 seconds per exposure, which really limits the ammount of drawing you can do. Then I hit upon the idea of making one pen that can do many colors!

So, I built the pen, and had my suspicions that I am a very poor artist--especially at high speeds--confirmed. Ever since, I've been trying to find someone who is an artist (like my brother) who could draw me a few nice looking pictures with this doohickey. I got impatient, and a while back I posted this instructable. It wasn't very popular, probably because it seemed a bit half baked, which it was. I wanted to post something about this light pen, but I was still having trouble finding someone to draw some pretty pictures to illustrate this intructable.

Well, all that is behind me now. I've finally decided it's time to post this thing and get it over with, even if all I have to show are my low quality 16 second scribbles.

Here it is in all of it's glory, the 7 Color Light Pen!

***UPDATE 5/4/10:  If you post your own light pen drawings in the comments below, I'll send you a patch!***

Step 1: Gather Parts

First and foremost, you're going to need an RGB LED with 3 anodes and a common cathode (or vice versa). You can either buy one, or make one from materials you probably already have on hand. Here's my RGB LED instructable if you want to make one of your own.

Also, you will need:
3 pushbutton switches
1 9-volt battery and connector
Some sort of case for the pen (I used the housing for an old microphone)
3 resistors (I used 2.2k for blue, 1k for green, and 330 for red)
A little extra wire
Hot glue
Foam rubber (for padding)
Electrical tape

Step 2: Wiring

The first step is to solder the resistors to the anodes of the RGB LED. Next, you'll need to install the LED in the end of the pen.

Since I used an old microphone for the casing, I discovered the battery fit nicely in the actual microphone part. I wired the positive end of the battery holder to the common cathode of the RGB LED and added a little extra wire to the negative end, which I shoved up through the point of the microphone casing. Then I hot glued the LED into the end of the casing, leaving the three anodes with their resistors and the extra wire attached to the negative end of the battery holder exposed.

Next I held the pen and marked the places where the tips of my first three fingers rested. Those are the places where the buttons will go. I hot glued the buttons in place, and then soldered one of each of the resistors to each of the buttons, and attached the extra wire from the negative battery lead to the other end of each button.

The last thing is to hot glue all the wires and stuff to the casing so nothing is sticking out and getting in the way.

Step 3: Wrap It Up

To finish it up, I added a bunch of foam to make the grip comfortable (see pictures). It's held in place with hot glue of course. Finally, I wrapped up the whole thing in electrical tape.

I discovered the battery rattled around a bit, so I inserted a couple of pieces of foam in the battery area to hold it still.

Voila, you're done! The first time I showed it to someone, they thought it was some sort of demented sex toy.

Step 4: Draw Something!

Grab your camera and find a dark room. Set the camera on a tripod and set it to it's longest exposure time. Hopefully your camera will do a little better than sixteen seconds, because that passes by WAY too fast!

****Edit 6/10: sjs229 has pointed out that I forgot to mention how this actually works! The three buttons when pressed down turn on one of the LED elements, red, blue, and green. When you mix these, you get different colors since they're so close together:
Red+Green: Yellow
Green+Blue: Cyan
Blue+Red: Purple
Red+Green+Blue: White

It takes a little practice to know what colors you're going to be getting, but you get used to it pretty quick.

Thanks to sjs229 for pointing this out! ****

Below are some examples of drawings and doodles my daughter and I have made.   If you post your own light pen drawings, I'll send you a DIY patch!

Please take a moment to leave a comment and a rating! I'd like to hear what you think, and I would especially like to see any projects you've made that were inspired or helped along by my instructable!

Once again, many thanks to unklstuart for this instructable for providing me with the inspiration!

Finally, please vote for me in the "Get the LED Out" contest! I really want those wheel lights!



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    how could you draw that fast

    Very poorly! It's really hard to draw anything in 16 seconds!

    so its kind of impossible

    Well, it's really difficult with my current camera. I'd like to upgrade to one with better manual controls for this and for astral photography, but those are kinda pricey.

    Is there a way I can make this reeeaaallly simple without paying 4 it. And can I make it so that I don't need a camera to show my drawings with the pen. It will just show in mid air and a way I can make it with no soldering?

    platinum, I suppose if you could find all of the parts you could probably make this for free, it would just be a matter of finding electronics to harvest from. If you just twisted all the leads together and used a lot of tape you could probably make this without soldering, but it would be pretty flimsy. However, you have to have a camera. What you are asking for here is magic, which unfortunately isn't real. Light does not just hang in midair, and if it did you wouldn't be able to see it since the light wouldn't be entering your eyes. Light has to be emitted from something, it doesn't stay put. Don't they teach this stuff in science class?

    Well...um they do...but u know... people think of so many things these days, wow that was a dumb question I asked >=( err. Well thank u for your help

    Sorry if I came across a little grumpy there, I've been reading a lot about the declining standards of science education and literacy in America. Did you know that 40% of Americans think dinosaurs and humans lived at the same time? And 55% of them think that atoms are smaller than electrons? Man, that's depressing.


    WOW.. that is depressing! As a Ph.D. student in the sciences who is a teaching assistant and does outreach programs with 5th graders and 11th and 12th graders, I have definately seen a decline, but didn't realize it was getting that bad!!