With this instructable I'm going to explain how I made Bobby, the scared gnome. This was a school assignment and I have never worked with arduino before, but I really enjoyed it!
Hopefully this instructable can help someone out :)
Step 1: Requirements
Photoresistor: To measure the amount of light, we use a photoresistor. If it's dark, a red led will shine, if it's very light a green one and otherwise a orange one.
Pressure sensor: If you pinch it's nose too hard, it's going to make a lot of noise. We need to measure the pressure and to do so, we use a pressure sensor.
LED: You will need six leds, two red ones, two orange ones and two green ones.
Piezo or speaker: This will make the noise when pinching the nose!
Apart from this, you will also need enough cables, an breadboard and an printplate for the electronics.
For the packaging you will need the following things:
Two black buttons
One white button
Dark red vilt
Skin coloured vilt
Clear wrapping paper
Clear stickers or clear tape
Step 2: The Circuit
The circuit I used for this project can be seen in the image.
Every seperate sensor circuit will at least need to be connected to the ground, and the input sensors will also need to be connected to 5V.
The LEDs should be connected to digital pins, as well as the button. The others sensors need analog pins to work.
Step 3: Trying Out the Circuit
Before actually soldering the circuit, I would recommend trying it out on a breadboard first. Start with one sensor and if this works, you can try everything together. This way you can easily spot any mistakes.
Another advantage is that this way you can try out a good place for each sensor, but also see how big the print plates have to be.
Step 4: Packaging - Papier-Maché
The packaging is quite a difficult point, since everything has to fit in and should be at the right place. It's recommended to make the packaging before soldering, so that you can see how long the wires between the different breadboards and sensors have to be.
Start with the head, you slightly blow up a balloon and make one or two layers with papier-maché, then let it dry overnight. The next day you can do a few other layers. It's recommended to not put on more than 3 layers at a time, because that will make it less smooth and strong.
It would be best to have around 7 layers.
Step 5: Packaging - Decorating the Head
To make sure you can place the electronics at the placed you'd like, it's handy to cut the shape in half and then put one side together with some tape, so that it can easily bend. On the other side you can put velcro, this way you can open and close it.
Since the head is already cut in half, you only have to make a little cut at the front so that the pressure sensor can come through.
After all this, you get the skin coloured vilt and put it over the shape. To make sure it fits and is smooth, you might have to cut some things away. You can put velcro at the back of the vilt as well, this way it remains easy to open.
Step 6: Packaging - the Hat
One of the most important components is the hat, since the colour will shine through it.
You start of with firm paper which you will roll in a spherical form, you have to keep the head close so that you can see when it fits well. If it does, you can staple the hat so that it stays in it's shape.
After this, you get the red vilt and draw circles at random places on the back of it, which you then cut out. You put it around the hat, and mark where the circles are on the paper. You also cut these out.
With clear stickers or clear tape you close the circles on the inside and outside and put clear wrapping paper inside the hat, so that the light will shine through it.
Lastly you can put the vilt on the hat and sew the back together.
Step 7: Packaging - the Body
The body is the easiest part of the packaging, because it's a simple vorm that needs just a few holes in it.
You start the same way you did with the hat, take some firm paper and make it in a spherical shape, until the hat fits well. You can keep it in the right shape by stapling. It might be a good idea to put an extra layer on it if the paper it not firm enough, this way you're sure it won't collapse.
On the back of the body you should make a hole for the press button, somewhere in the body a hole for the speaker (I put mine right on the front) and at the bottom you should make an opening for the USB cable.
After this you get the red vilt and glue it on the body, it doesn't have to cover everything because you will also need dark red vilt, this you have to wrap around it from the top, so that it looks something like a cloak. To give it more the illusion of a cloak, sew a button to it!
At the back of the body, glue a little heart at the place where the pushbutton is coming. This way you always know how to calm him down.
Step 8: Soldering - Plan It Out!
It's very important to plan everything out before soldering, this way it will hopefully go right the first time!
You should measure how long the different wires have to be and how much space there is between the different sensors. It's also a good way to make sure the ciruit is totally clear and right.
If you know how large the breadboards should be, you can start cutting them the right size. It's recommended to make it a little larger than you measured, so that you have some space it you mess something up.
In the image you can see one of my plannings/sketches, I made quite a lot before I had it right, but this way it went right with soldering the first time!
I waited with soldering until the packaging was nearly finished, so that I could measure how far everything had to be away from each other.
Step 9: Soldering
It's time to start soldering! Make sure you have your planning near, this way you can fall back on it if you're not sure about a thing. At first you should put everything in the right place, to make sure it fits. Then you can start soldering! It might be handy to bend some of the wire ends, so that it can easily reach the Arduino or other breadboard.
Tip: don't solder everything at ones. Try every sensor after you're done, this way it's easier to see where the mistakes are if something doesn't work.
Tip: Make sure you put the LED lights in the right way! This way it might save you a lot of time and frustration :')
Step 10: Putting Everything Together
If everything works you can start with putting everything in the right place! This might be quite some work because of all the wires and sensors.
If you followed my circuit, it should be somewhat easy, because I made sure every sensor is plugged in on the right order, so that they aren't in eachother's way.
Some sensors/breadboards might stay at the right place by itself, for example if it's stuck. Otherwise you can use tape or glue. Especially the button on the back of the body should be attached properly, otherwise it will fall once you press it.
The photoresistance sensor can be put between the head and the body, because once you sew those together, it will stay at the right place.
Once everything is in the right place, sew the body and head together! The hat you can put on with tape, glue or sew it as well. The Arduino itself can either be left hanging, or be attached to the inside of the body. I'd recommend the latter, since I feel like that way you make sure it keeps working and nothing breaks.
Step 11: Enjoy!
You finished your scared gnome!! Hopefully you've enjoyed making this as much as I did. :)
Step 12: The Code
At the images you can see the code I used.