In these instructions we will show you how to create a light-up holiday card using Circuit Scribe, 2 LEDs and a sheet of standard printer paper.
Here is what you'll need:
Circuit Scribe conductive ink pen
A pencil and eraser
8.5x11" sheet of printer paper
2x Through hole LEDs (Super bright if possible! Available at Sparkfun)
Tweezers or pliers
1x 3V coin cell battery
Colored pens, pencils, or markers
Step 1: Simulate the Circuit
Here is a simulation of the 2-LED circuit that you will draw in your card. The card itself will use through-hole LEDs, paper based pushbuttons, and a coin cell battery, but this is a good illustration of how the card will work. Press the "Start Simulation" button to try it out! You will see that each LED is individually addressed by its own switch.
Step 2: Fold and Cut the Card
Start by creasing the paper into four sections and folding over twice. When you place the card on the table and open it up, the long crease should be on the top edge of the card.
Next cut trim the card along the inner crease from the bottom up about an inch. Only cut through one layer of the paper. Fold over the triangular flap with a soft crease. Repeat this step in the top left corner. These flaps will become buttons for your electronic greeting card.
Finally, fold in the bottom right corner over using a soft crease. This will become the battery holder.
Tip: Since we'll be drawing over the these folds with Circuit Scribe ink, try to make a soft bend rather than a hard crease.
Step 3: Illustrate the Cover
We sketched an umbrella scene with a rainbow and clouds. Plan on having two areas of your design light up from behind - we'll illuminate the clouds with yellow LEDs to represent lightning!
Step 4: Mark the LED Location
Figure out where the lenses of the LEDs need to be placed to align with your cover drawing. Mark this spot lightly with a graphite pencil line.
Step 5: Modify the LEDs
You'll need your tweezers or pliers for this step! Curl the terminals of both LEDs into a flat spiral. The spirals will end up being about 5mm in diameter, and looking a little bit like a mustache. They are also the perfect terminals for taping into the holiday card in a later step.
After modifying the LEDs leads, try lighting up each LED with the coin cell battery. Mark the negative terminal of the LED with a permanent marker somewhere on the lens - this will help you orient the LED correctly later!
Step 6: Create the Switches and Battery Holder
The bottom left and top right flaps will be switches that act like momentary buttons. The pattern we used are two triangles on either side of the fold. When you fold over the flap and apply pressure, the large circular pad on the flap connect all of the fingers, completing the circuit.
Tip: you don't need to completely fill in the triangles! A random or regular line pattern will work well.
The battery holder is similar: it is a large silver ink pad on the main area of the card and a second round pad on the triangular flap. These circles should be filled in completely.
Step 7: Design the Circuit
In this step you will create the circuit pattern! We suggest drawing the pattern with pencil first in case you make any mistakes. Then erase the pencil and draw the same pattern with Circuit Scribe.
1) Start by drawing two pads to either side of the LED marks. They should be about 5 mm wide and 5 mm apart. It will be helpful to use the LEDs themselves as a guide. In our example, we drew the pads above the pencil marks and plan to point the LEDs downward.
2) Next wire up the flaps of the two switches by drawing lines from the corners of the two outer triangles to the outer battery circle. You might need to draw a little extra ink on the lines where the paper folds over.
3) Then draw traces for the LED closest to the bottom switch. Draw a line from the inner battery pad (circle) to the right-hand LED pad. Leave a gap for the LED, and continue drawing a line from the left-hand LED pad to the inner triangle of the bottom switch.
4) Now repeat the process for the second LED. Draw a line from the left side pad to the inner pad of the battery. (tip: instead of linking directly to the battery pad, you could connect anywhere along the line that is already drawn to it.) Leave a gap for the LED, and draw a line from the right hand pad up to the inner triangle of the top switch.
Step 8: Add LEDs
1) Start by figuring out the polarity of the LEDs and battery, and marking (+) and (-) signs with a pencil. We're going to make the inner pad of the battery negative. For the LEDs, the pads that are directly connected to the (-) pad of the battery are also negative (-). The opposite pads are positive (+).
(In the photo, we used a black pen so you can see the (+) and (-) signs!)
2) Attach the first LED by pressing the positive and negative leads over the corresponding pads, and attaching with Scotch tape.
3) Repeat step 2 for the second LED!
You can go ahead and test your circuit now by folding the battery holder over the coin cell and pressing each of the button flaps down. If it doesn't work initially, try reversing the direction of the battery or reinforcing your circuit pattern with more ink.
Step 9: Embellish!
After you get the guts of your circuit card working, you can embellish the traces with more lines and patterns! We drew some rain drops to go with our umbrella theme.
Step 10: Light Up the Card!
Use a binder clip to hold the coin cell battery in place. You can remove one or both of the binder clip arms to reduce the thickness of the clip. Then press the paper switches through the outside cover of the card!
Now you can create your own designs! Some themes that work well for light-up cards are a string of Christmas lights, candles, or a city skyline. Leave us a comment below, or send us a picture of what you create!