Alright, so I just spent some time toying with paper circuits. I decided to do a few things with these little artist trading cards I have–very small (baseball-card size), so perfect for just testing things out. I used a coin cell battery and battery holder, alligator clips (borrowed from a Makey Makey kit), conductive tape, scotch tape, the trading cards, and surface mount LEDs. I think it’s size 1206 that you want for the LEDs, because Sparkfun is telling me I ordered those back in March, but truth be told, I went through a bit of hell ordering various surface mount LEDs in an attempt to find ones I could use; the first ones I got were TEENY TINY (like, smaller than a grain of rice; they don’t look tiny in the picture, do they??); these are usable, but maybe a bit too bright.
Because what I’m ultimately practicing for is a hacked journal with battery in the back and clips, I just took my conductive tape to the edge of the page and then connected there. So I made these two little pictures, and just used white lights because I wasn’t really concerned with product and I wanted to save my colored lights. In retrospect, my issues with things being too bright might be tamed by using colored lights that match the color of the marker–will try that tomorrow or later tonight.
Under the hood (separate cards, with the circuits on them, lined up so that the lights come through in the right places):
As you can hopefully see, this is very basic and pretty easy. The only tricky part is the LEDs. The ones I am using are small. Here is one on top of a penny:
Note the green arrow thing–if there’s an arrow, the arrow points towards negative. If there’s a T, then the part of the T that would be the bottom points toward negative. (I think!) That other picture is a set of the LEDs. When I first ordered them, I didn’t realize that the black stuff is just the casing that they are in, so I’m including that picture so you don’t make the mistake I made! There is a clear film that holds them in, and when you peel it back, the LEDs will pop out.
I just used scotch tape to put the LEDs on the paper, with one end (in my case, I’m always making the top positive) touching one piece of conductive tape and the other touching the other piece, with the light part facing up and the green arrow part facing down. With the stars, it worked right away, but the monster required some re-taping before the connection was good. I have tried in the past to solder those surface mount LEDs, and let’s just say my sanity is too fragile right now for me to attempt that again anytime soon, so I’m sticking with tape (no pun intended).
This pic shows the battery holder I used, which is just a basic sewable battery holder from Sparkfun that I bought for etextiles.
And that is all! It was very easy and fun, and I feel like I am ready to get crazy and start building switches and more complicated pictures. I will probably play more before I do start on a journal or sketchbook, but this was a good start.