## Introduction: Solar Powered Miniature Smart House

This house began as the project-based assessment for my physics classes' circuits unit. Students wired lights, doorbells, & alarm systems on miniature houses or castles that they made. Once they were done with the basics, they added custom components like exterior house lighting, trap doors, fans, and automatic draw bridges. They converted their houses to run off solar power. Finally, we added automation to the house using the Hummingbird Duo controller to make it truly a "smart" house.

## Step 1: Make or Find a Miniature House.

I started by checking out Goodwill and thrift stores for doll houses that I could convert into a smart house. I ended up finding a dollhouse kit on clearance and put that together. Some of my students used wooden castles we found at Michael's crafts store.

## Step 2: Wire Your House With Lights, Doorbells, Fans, Etc.

Add LED or mini-Christmas tree lights to each room or in front of each window. If you use LED lights, add a resistor to each light (about 100 ohms) so that they don't burn out. When prototyping my house, I used an old string of incandescent Christmas tree lights, cut it apart, and stripped the ends on either side of each light.

## Step 3: Power Up Your House With a Battery to Check Your Connections.

Use a 6V battery to power your house and make sure all the lights, buzzers, and fans work.

## Step 4: Check How Much Power Your House Is Using.

Connect a multi-meter in series with your battery. Check how much current each device is using. Calculate the power your house uses by multiplying the voltage of the battery and the current. P = IV. If you want to find the minimum power needed to run your house, connect a variable power supply. Turn the current to max, then slowly increase the voltage until all your components work. Your house will probably need a lot less than 6V.

## Step 5: Switch Out High Power Components for Energy Saving Components.

Which components used the most power? (Probably the incandescent Christmas tree lights.) Switch these out for LED's. Re-check the current used by your house.

## Step 6: Switch From Battery Power to Solar Power.

Now that your house is working and you have the most efficient components, let's convert the house to solar power. You can determine the number of solar panels you need and their configuration by trial and error or by using calculations.

1) Try & Error: Hook your house up to a solar panel. If indoors, shine an incandescent light on the panel. If everything on your house doesn't work, add another panel in series. If that does not work, try parallel.

2) Calculations: Add panels in series to get the voltage needed. Add panels in parallel to get the current needed.

One high quality panel such as found at www.rechargelabs.com should be sufficient.

I then converted my working solar-powered house to a smart house. I used the Arduino-based Hummingbird Duo and the sensors available in their robotics kit: http://www.hummingbirdkit.com. To run the Hummingbird Duo off of solar power, cut the plug off the cable. Pull apart the positive & negative leads and strip the ends. Connect the ends to your solar panel.

## Step 8: Add a Control Panel in Scratch.

Create a control panel by importing an image of a house. Display your variables using sliders on the screen. Your user will be able to set the temperature, light level, etc. from the control screen.

## Step 9: Add a Temp Sensor and Servor to Make an Automatic Porch Shade.

Using Scratch, add a temperature control slider. If the temperature in the house exceeds the desired temperature, the servo motor brings the shade down.The shade is made from a wire coat hanger bent into a rectangle, then mounted on the first floor of the house with hinges. Extra fabric made the shade itself.

## Step 10: Add a Party Room!

I took apart an old mini disco ball and add tri-color LED's. I removed the wiring to the batteries and wired the motor into the Hummingbird controller. Using Scratch, I added a "Party" setting. The higher the setting, the faster the disco ball turns, the faster the LED's blink, and the louder the music plays.