Alexa Based Voice Controlled Rocket Launcher

As the winter season approaches; comes that time of the year when the festival of lights is celebrated. Yes, we are talking about Diwali which is a true Indian festival celebrated across the globe. This year, Diwali is already over, and seeing people fire crackers, I came up with the idea of building the Alexa based Voice Controlled Rocket Launcher or Igniter, which can launch rockets with just voice command, making it very safe and fun for children.

To make it clear, I am not here for encouraging people to fire crackers on Diwali, the Indian government has enforced restrictions on crackers to curb pollution and it is our responsibility to adhere to it. The idea here is that instead of spending the whole day firing crackers, let's build a cool voice-controlled Arduino rocket igniter and fire a few rockets in style. I see that as a win-win.

This Arduino rocket launcher will be very different from others. It has a very sturdy chassis made out of plywood, a reliable relay-based control mechanism, and a very unique mechanism for launching and reloading the rockets, so without further delay, let's get right into the building process.

The working mechanism of the circuit is very simple, the main component which is responsible for launching the rocket is the nichrome wire, and it comes in the form of a heating coil. This nichrome wire will act as the rocket igniter. How? I will show you later.

As you can see in the image above, the nichrome wire comes in the form of a heater coil, for me, it was the easiest way to get it. We have to pull it straight and bend it to form a shape that looks like as shown in the image.

Once we have done this, we will power it with a 12V lead-acid battery and it will glow red hot. This will be enough to ignite the black powder inside the rocket and it will work just like a normal fuse dose. Be advised that this is a high power rocket launch controller, the current required to make the wire red hot is high. Follow safety advice when working with high currents.

Once the testing is done, the only thing remaining is the controlling process, which we will be doing as we proceed further in the article.

For this build, let's make a launchpad. With the launchpad done, we can easily reload some crackers and launch them very easily. I have built a launchpad that looks like the one shown in the image.

Let's go through the step by step process of building the launchpad.

• For the two sides of the frame, I have used two (25X3X1.5) inch long pieces of plywood.

• For the top part, I have used a (20X3X1.5) inch long part of plywood and for the base, I have used a (20X6X1.5) inch long piece of plywood, which will give it a little more stability.

• Now, it's time to make the nichrome wire-based filaments, which will act as a fuse for our rocket.

• For that, I have bought a 1000W nichrome wire base heating coil, straightened it up, and made the structure which is shown in the image. I had to use two pliers and side cutters to shape the nichrome wire as shown.

• Once this was done, I divided the 20” piece of plywood block into seven pieces measured it and drilled holes to put the nichrome wire-based filaments in, and once it was done, it looked like the images below.

• But before placing the filaments, I have attached 1 sq mm thick copper wire in each terminal and passed them through the holes, once everything was done.

• As you can see, I have also put in the two-component adhesive to secure the wire and filaments in place. With that done, our launchpad is complete.

• And as you can see from the first picture in this section, I have directly attached the filament wires to the PCB because we are dealing with very high currents so I did not bother to place a screw terminal, and that marks the end of our chassis building process.

For the hardware side of things, we have used very generic parts which you can get pretty easily from your local hobby store, a complete list of items is given below.

12V-Relay - 3

BD139 Transistor - 3

1N4004 Diode - 3

5.08 mm Screw Terminal - 1

LM7805 - Voltage Regulator - 1

100uF Decoupling Capacitor - 2

5.1V Zener Diode - 1

NodeMCU (ESP8266-12E) Board - 1

Dotted Perf Board - ½

Connecting Wire - 10

The complete schematic for Alexa Controlled Rocket Launcher is given here.

I have used tags to connect one pin to another. If you look close enough, it should not be difficult to interpret the schematic.

The Circuit Construction is pretty straightforward, So I will not go into the details very much.

First, we have IC1 which is an LM7805 voltage regulator, with its 100uF decoupling capacitors denoted by C1 and C2.

After that, we have the heart of our project, the NodeMCU board, which houses the ESP-12E module. Since we are using a 12V lead-acid battery to power the whole circuit, which is why we have to use the LM7805 to first convert it to 12V to 5V to power the NodeMCU board. We are doing so because the onboard AMS1117 voltage regulator is not sufficient enough to convert 12V directly to 3.3V, which is why 7805 is necessary.

Moving on, we have three 12V relays, for this demonstration, we are using three relays, but as we have previously mentioned, the launchpad has a placeholder for 7 rockets. You can tweak the code a little bit and place all seven rockets to launch altogether. The three relays are driven by a T1, T2, and T3 which are three NPN transistors, and they are sufficient enough to drive the load of a real. Finally, we have three freewheeling diodes that are protecting the circuit from high voltage spikes generated by the relay.

As you can see from the main image, the idea was to make a simple circuit that can handle a huge amount of current for a short period, as per our testing, 800 milliseconds is enough to light up a piece of paper. So, we build the circuit on a piece of perfboard and connect all major connections with 1 sq mm thick copper wire. After we finished soldering the board. Once we were finished, it looked like something as shown in the above image.

Now that the hardware is ready, it's time to start coding for our Alexa based voice controlled rocket launcher. But before we start, it is important to add the required libraries to your Arduino IDE. Make sure you add the right libraries from the link given below else the code will throw errors when compiled.

• Download Espalexa Library

After adding the required libraries, you can directly upload the code to check if the circuit is working. If you want to know how the code works, then keep reading.

Alexa will only accept commands if and only if it recognizes the ESP8866 device. For that, we need to configure Alexa with the help of the Alexa app on Android. One important thing to do before we proceed any further is that we need to make sure the Alexa and the 1 (The Sentence is incomplete)

To do that, go to the more section of the Alexa app and click on the Add a Device option, click on Light, then scroll down at the bottom of the page and click on Other.

Next, click on DISCOVER DEVICE and wait for a moment after that Alexa will find new devices. Once Alexa finds the devices, you need to click on them and add them to their respective places/categories, and you are done.

For the testing process, I went to my garden, pulled all the fuses from the rocket, placed them in their respective places, and I shouted Alexa…! Turn on all Rockets, with my fingers crossed. And all the rockets flew by marking my efforts as a huge success. It looked something like this.

Finally, once more I said Alexa…! Turn on all rockets, to get an epic picture of the filaments which you can see below.

I hope you enjoyed the article and learned something new and useful. If you have any doubt or queries, leave them in the comment section below. For more such interesting projects, you can visit CircuitDigest and IoTDesignPro also follow us on Instructables.