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This is a straightforward exercise - I had been using 5mm LEDs before but it was tough to light up more than 2 or 3. Also, the 5mm copper tape I was using was sometimes not as reliable as I would like.

A 3V battery will light up 7 SMD LEDs no problem, I also used industrial conductive tape (can't remember the brand).

Step 1: Gather Your Materials

Conductive tape

Scotch/other tape

Foldback clip/bullclip

C2032 3V coin cell battery

Tweezers

1206 Surface Mounted LEDs x 7

Coloured Card

Pencil & Pen

Ruler

Cutting knife

Other Basics:

Soldering iron

Solder

Helping hands

Multimeter - to check continuity of circuit and to check battery voltage if circuit i not working properly

Step 2: Make Your Card

Cut your card to the size you need.

Overlay an image on the front that you would like to "light up".

Step 3: Make Your Holes

Decide what parts of the card you want to light up and make a hole through the card with a pencil or something else.

When you have made your holes, make sure the pencil marks are made through the front of the card to the inside of the card - you will use these pencil marks as a guide to where your LEDs will be soldered.

Step 4: Mark the Battery

Decide where your battery will go, create a fold and and draw an outline with pencil.

One circle will represent +, the other will represent -

When folded the circuit will be complete and the LEDs will light up.

Step 5: Draw Your Circuit Track

Draw a + and a - track in pencil alongside each pencil dot (LED marker) on the inside card. Straight lines are best because the tape will be applied in straight lines.

The SMD LEDs are tiny and will be placed across the tracks, connecting + and -, so the tracks should be be spaced no more than 2/3mm apart. If the gap between the + and - tracks is too wide a connection won't be made - you should, however, be able to use solder to bridge the gap if necessary.

When you are happy with your penciled tracks, go over them in pen, they will be easier to see.

Step 6: Conductive Tape

My tape is 1 inch wide and it was very expensive! So I cut it into strips and lay down my + and - tracks using the previously penned lines as a guide.

You can also use copper tape here - I'm sure any adhesive conductive tape will do the job well.

Step 7: Check the LEDs

Before sticking and soldering the LEDs, check the back of each one to make sure you know which is positive and which is negative.

Different SMD LEDs have different polarity markings.

I used this site to tell me:

http://www.limetrace.co.uk/how-to-determine-the-po...

You can lay each SMD across the tracks to make sure they all work and they are all positioned correctly.

Step 8: Tape & Solder LEDs

SMD LEDs are tricky enough to handle, even with tweezers! I decided to tape down one side of each in order to hold in place while I soldered the other side of the LED.

Step 9: Clip the Battery

Using the foldback or bulldog clip, connect your battery. You will need to make sure the + side of the battery is touching the + track, the - side of the battery touching the - track. Make sure the + and - are not touching each other.

All the LEDs should light up and your card is finished, yay!

If LEDs are not lighting up:

Check the voltage of the battery using a multimeter, reading should be close enough to 3V

OR

Check the continuity of the circuit to see if there is a break somewhere that needs to be joined

OR

Check the individual LEDs to see if there are working.

This is my first Instructable so I hope you liked it!

Please post pics of your paper circuits

<p>Why not make things even more simple and just use some standard 3mm or 5mm LEDs? Then you wouldn't need to solder them. Just tape them to the conductive tape. Surface mount LEDs are a massive pain in the rear for most people, and especially students.</p>
I started using 5mm LEDs (as I mentioned in my intro), they don't work well at all taped down and will only light up 3 max using a 3v battery, and even then they're not so reliable. SMDs are tricky to use but are worth it, students much prefer them too because 3V will get at least 7 SMDs lit.<br>If you're working with under 12s I can see that they may not suit you so try https://store.chibitronics.com/collections/all/products/red-yellow-and-blue-megapack-circuit-stickers
<p>What a fun card! I love paper circuits! </p>

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