Remote Control Catapult

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About: I'm a teenager who likes computers and baking and pretty much everything else. I also like to force my family to help me with Instructables

I got an Arduino for Christmas and it took me a while to set it up. I got used to it after a bit and decided to start my first big project. A catapult. Because catapults are cool. But my catapult had to include a few things.

  1. It had to be small.
  2. I had to be able to launch it from a distance.
  3. It had to look like something older sister wouldn't suspect was really a catapult so I could do sneak attacks.
  4. It had to be within my range of skill
  5. It had to be inexpensive.

After a lot of googling and a visit to my great-uncle for Arduino lessons, it's done.

Step 1: What You Need

Techwise:

Catapultwise:

  • A lightweight ruler
  • A box that will fit your catapult (I used the one my remote controller came in.)
  • A weight
  • A plastic cup

Toolwise:

  • Scissors

Step 2: Setting Up the Arduino

For the servo, I'm going to tell you something you might already know. They have 3 wires to connect, ground, power, and signal. Brown is ground, red is power, yellow is signal. So brown is connected to the negative power rail, red is connected to the positive power rail, and then connect yellow to pin 9 on the Arduino.

Now onto the remote control. I used the little remote control thing listed in the parts list because I was already ordering some things from that place and it was on sale. (I love sales.) But you can use another way of remote controlling. For my thing, I connected a pin from the ground to the negative power bus and 5v to positive. Then I connected the d0 pin to pin 2 on the Arduino.

Connect the 5v pin on the Arduino to the positive bus and the ground to the negative. Then I connected the Arduino to the not-USB power source, and it should work.

I have a nice little diagram made in tinkercad circuits, but I didn't realize I had it until after I typed all this. Oh well.

Code time!

#include <Servo.h> 

Servo servo_9; 
void setup()
{
  servo_9.attach(9); 

  Serial.begin(9600); 

}

void loop()
{
  if (digitalRead(2) == 1) {  
    servo_9.write(90); 
        Serial.println(digitalRead(2));
    delay(1000);
  } else {
    servo_9.write(0);
        Serial.println(digitalRead(2));
  }
}

It's also here: link

Okay, that's over. Let's actually build this catapult!

Step 3: Setting Up the Catapult.

I took a plastic cup and cut off the top. I then glued it to a lightweight ruler and taped it to a cap that came with my servo, and that was my catapult arm.

For the base, I took my box and cut holes where they were needed. There were 3:

  • One hole for the battery switch.
  • One hole for the antenna.
  • And one hole for the servo.

I put the electronics stuff in the box. The breadboard was partially stuck to the wall to keep it stable, and the battery pack was taped to the wall to help keep it from sliding around. To get the servo in, I had to detach it and stick the wires in first.

I stuck a weight inside the box very carefully, as not to squish anything, with the box tipped sideways. This kept the catapult from tipping over when it moved. Then I attached the arm and started launching.

Step 4: Disguising Your Catapult.

It's really fun to launch things at people, but it's even more fun to surprise launch things at people. So you can hide your catapult! Here are a few steps to getting a successful hiding spot:

  • Know your victim. Knowing who to hit helps to choose a good location.
  • Choose somewhere messy. Nobody will notice more clutter.
  • Use common items. Plants are always good, you can even hide the arm with a leaf.
  • Time it right. If you launch the catapult while your older sister is angry, she will get angrier and that is not good.

I ended up putting the catapult next to my older sister's chair and waiting for a while. My mom sat in the chair by accident and ended up getting hit. She thought it was hilarious. My older sister, however, was very displeased when she got hit.

Step 5: Throw Things at People.

Now you have a small desktop catapult that you can use to bombard your enemies and destroy their things. It'll be super fun!

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