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We're creating a light up Gingerbread house, where when you touch the chimney top, the house will light up inside.

This project is a really fun intro to circuitry, and intended to demo, including both a little bit of basic circuit making and a little bit of laser cutting & assembly.

### Supplies:

• 3 Volt Coin Battery (CR2032)
• LED.. Color of your choosing
• 2N2222 NPN Transistor
• 14 inches of copper Tape
• Glue & Tape
• Birch Plywood, or other 1/8 inch laserable material.
(You could cut this out with out a laser cutter, out of particle board, or plywood)

Battery:https://www.amazon.com/gp/product/B01FMWDTDU/ref=p...

### Teacher Notes

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## Step 1: Create Your House

I drew a house in Illustrator, starting with some with basic dimensions.

General Layout
I wanted the width of the base box to be about 3 inches square, and the depth to be about 4 inches
(I went with 3 & 7/8 for symmetry reasons)
.

With a 45 degree roof.

These decisions allowed me to design my basic pieces.

Building it Out:

Taking the depth of the wood in to account
Because I was going to be cutting this from 1/8 inch plywood. I then added & subtracted tabs 1/8 of an inch deep, so I had places where I could slot and glue the pieces together.

Creating a Circuit Board
I wanted to be able to draw out the circuit, so I could see how the circuit was supposed to be functioning, and identify what symbols belonged to which pieces.

*** Please NOTE: A .svg file, for the basic template & circuit board can be found at the bottom of this instructables step ***

Embellishing

The house was going to need some windows for the light to shine through... so I played with that a bit, and changed up the roof line a bit.

Cut it on the Laser
The laser at the FCC MakerSpace
cuts: red lines
vector engraves: blue lines
engraves: black and white.

Cut it again, when you realize you goofed on something, or had another BRILLIANT idea! You can find the basic template below in an .svg file.

## Step 2: Glue SOME Bits of the Together

You'll want to glue up some of the bits of your house together. But NOT ALL of them, so you have access to the inside of your house, to put in the electronics.

I glued:

• The house walls to each other
• The house roof separately
• The house chimney separately

## Step 3: Understanding What We're About to Build

We're trying to build a circuit, that will allow us to turn on an LED light with our finger.

Simple Circuit
A really simple circuit, where we connect the battery to the LED, then back to the battery, will keep the LED light on all the time, until the battery runs out of electricity.

Simple Circuit with a Switch
So we want to include a switch, to help us turn it on and off. A really simple switch would be just to have a small piece of wire, or copper tape that we take in and out. When we put the wire in, the circuit would be complete, and the LED would turn on. Take it out the wire, the LED would turn OFF.

Using a Transistor
A transistor, is a special kind of switch. It sort of creates 2 circuits, with a "traffic monitor". I imagine a little police officer with white gloves blowing a whistle. In the transistor were using (NPN) the traffic monitor says, "IF there is current on the first circuit, THEN close the second circuit, so the current can flow and turn on the LED. OTHERWISE just top all traffic."

This specific transistor, can detect a low amount of current on the first circuit, so when our finger completes it, (which will not nearly as much electricity as would flow through as a wire), it will be enough to alert the traffic monitor, and that will allow current to flow through the second circuit, turning on the LED.

An LED is polarized, that means it will only work if the electricity is running through it in the correct direction.

* Note: this is why you see them connected to battery packs a lot. In order for them to connect to an outlet, they need a rectifier to change the flow of electricity from AC (Alternating Current ... going back and forth) to DC (Direct Current) flowing steadily in one direction.

- The long end of the LED is the (+) side, and the short end is the (-) side.
- On your coin battery the outer edge, and one face is the positive (+) side, and the inside face is the negative (-) side.

Touch the (+) side of your LED, to the (+) side of the battery & the (-) side of your LED to the (-) side of the battery. Your LED should light up! If it doesn't light up, you either have it turned the wrong way, or one of your parts is broken. Can you figure out which?

* You don't get shocked buy touching a small 3V coin battery, because their isn't enough voltage and amperage to hurt you.

## Step 5: Creating the Circuit & Board

We're using the copper tape, and the wooden pieces to build a really simple circuit board.

Make the Board: Slot the central chimney piece in to the wooden base. (I put a little extra tape on the back of mine to keep them together nice and snug. But you could also glue them together.)

Building the Circuit:.

1. Use the copper tape to create a connection from the battery, up to the top of the chimney. You'll want to make sure the tape is folded down along the inside of the battery hole, so it makes a connection with the positive side of the battery.
2. Use another piece of tape to make a connection from the top of the chimney to what will be the base pin of the transistor. Make sure these 2 pieces of tape don't touch or overlap.
3. Then use a small piece of copper tape to create a connection from what will be the emitter side pin of your transistor, to the (+) pin on your LED.
4. Finally add your coin battery (+) side down, with the wall of the battery touching the tape.

On the Second Board We're going to add our LED, and transistor. So when this is placed on top of our "circuit board" the pins, from the LED, and transistor will touch the correct wires.

The LED

Place the LED pins through, and bend them flat to the board, but it's OK if they spring back a little, that will help them make contact with the copper tape, and battery. Insure you have put the LED pins in, in such a way that the positive (+) side touches the copper tape leading back to the positive side of the battery. And where the negative (-) side of the LED will actually touch the negative (-) side of the coin battery.

The Transistor

The Transistor, also expects a particular polarity, so we will want to line it up right. The middle pin, (called the Base) will go to the part of our circuit that we will close with our finger. The Collector pin, goes on the part of our circuit attached to the (+) power source. The Emitter pin, connects to the part of the circuit that leads to our LED.

## Step 7: Assembling the Circuit Board and Components

Once all the components are in place,slide that board down over top of your circuit board.

* I found a little tape helped keep the boards in contact so pins stayed in contact with the copper wire.

IF your LED doesn't light up at this step, check your connections, and the polarity of your components. Only change/check one thing at a time, this will help you trouble shoot the problem. If you have some spare copper tape, this may help you check things as well.

## Step 8: Finishing the House

Place your assembly in the house (Test it again to insure nothing has wiggled loose... and because it's fun)

*I found some tin foil on the inside of the roof brightened it up a bit.

## Step 9: Food for Thought

What would you do to make it cooler? Better?
How could you add more light?
Have you noticed some people light it up brighter than others? I wonder why?
What would you need to add more LED's? Should they be added in series or in parallel?
Could there be LED's on the roof?

Share Your Creations!! I would so love to see them.

This is an entry in the
STEM Contest

273
50 25K
211 13K

## 2 Discussions

Thanks seamster,
I'm looking forward to painting one, and having the kids join the fun too!
(p.s. love the lego guy profile pic)