Today I'm going to show the everyone the process of making a LED Christmas Tree Card. This is a great project for learning about LED's, batteries, circuits, and soldering. The cost of the electronic parts came out to only about 40 cents and a 9 Volt battery (Tayda electronics!), and shipping...
Step 1: Aquire the Supplies
4 green 5mm LED's
1 red 5mm LED
1 100 Ohm resistor
1 switch - I used a spdt
1 9 volt battery connector
1 9 volt battery
Piece of cardboard or mat board, any paper that can stand up stiff and supports the 5 LEDs
A piece of tape about 4 inches long
Hole Punch (not exactly necessary but helps a ton)
Small Pliers or tweezers
Soldering Iron (little bit of solder and flux)
Step 2: Solder the Green LEDs
First your going to want to bend the leads of the LEDs to a 90 degree angle about 1/4 inch below their bottom surface. This is about twice the distance to the little pre existing crease spot and gives you room to bend it around on the card at the end. Also make sure to bend two of them on direction and two the opposite direction. They are put in parallel in the circuit so the long leg should be soldered to the long leg, and short to short.
I forgot to put the switch in the schematic, but it can go almost anywhere besides between the green LEDs.
Step 3: Solder the Red LED
Now go ahead and solder in your red LED. Bend it in a 90 just like the green LEDs, but pay attention to the schematic so it's going the right direction. I was using about an inch of wire from the 9 volt connector to elongate the whole part.
Step 4: Punch Holes in Card
To properly place the wholes where the LEDs poke through the card I first punched a whole in the top of the card; centered and about an inch down. I also punched a hole for the switch. The switch hole took two punches, a whole punch a crescent moon looking punch to make the final hole an oval. That made the leads on the switch fit through the card and made it kinda snug which helps with the soldering. Then I put my LEDs pointed down on the card face down and marked my locations for the green LEDs.
Step 5: Finish It Up
Now punch your final four holes for the green LEDs. I trimmed my card to more of a tree shape so my hole punch could reach all the spots. Push the LEDs through the card, bend the red led down and the green LEDs up. This holds them in place and gives that nice tree looking light pattern. Size up, trim, and solder in your resistor, it's hard to see but it's behind the red wire at the bottom. Solder in your 9 volt connector, connect and tape in the battery, and if all your LEDs are in the correct orientation you should see the light!!
The circuit should use about 9 mAmps depending on the LEDs, so with a 9 volt that has about 565 mAh lifespan you will get at least 2 days of light. Mine dimmed over time and was still running 5 days later!! You could swap to a 47 ohm resistor if you want it bright, but I decided a longer lifespan was preferred (the 9 volt is, by a factor of 2-3, more expensive than everything else).
I originally made these for my mothers first grade class to decorate, they loved them. Building 40 however took a very long time,so if you undertake that operation make a template for the cards and get a buddy to help with all the soldering.