It is the Diwali season here in India, and I no longer have the interest to fire the Crackers. But I am all for celebrating it in a nerdy way.
How about firing the Diwali rockets wirelessly?
Diwali falls in three days. So I am going to take a dirty way to do this.
No pyrotechnics, no chemicals, just a frugal method!
Step 1: Things Required!
Pendulum Stand - 1 pc (It is going to be the launch tower)
Stepper Motor - 1pc (I used a NEMA17 stepper)
Timing Belt - 50cm
Motor Coupling & L-Clamp - 1pc
Ball head clamp - 3 pc
ESP8266 NodMCU - 2 pc
A4988 Stepper Motor Driver - 1pc
11.1V Li-Ion Battery
3.7V Lithium Polymer Battery - 1pc
Step Down and Step Up DC DC Converter Modules - 1 set
Li-Po battery charger module - 1pc
8 digit, 8 segments LED Display module - 1pc
BBQ Gas Lighter - 1pc
Tripod Mount screw and Tripod (Optional)
Access to 3D Printer
Step 2: The Ignition System!
Initially, I tried with a 24 Gauge nichrome wire which we could use it as a heater filament using electricity. But it took a hell lot of current to even barely heat it up. I thought a 38 or 40 gauge nichrome would help. So I ripped it off my Iron box and took few millimeters of it. But again it needs a tremendous amount of current.
I want to fire up the rocket from my 11.1V Lithium-Ion battery.
Other makers have found some nerdy ways to do this.
GreatScott[YouTuber] used a low wattage resistor to burn and create fire. Though it works, a new resistor has to be used in every single launch.
I am going to make an even simpler ignition system.
I brought a BBQ gas lighter. This requires at least 10N force to put the flame on the tip.
Let's see if we can build an ignition system using this lighter.
We can use a solenoid to do this. But still, it requires a lot of current. I tried with Solenoids of various forces. Though it worked, it took a lot of current that my batteries can't cope up with. So let's build a linear actuator to press the trigger.
Step 3: Ignition Side Electronics
I am going to use a NEMA 17 stepper motor. Originally I bought this for my 3D printer and a step-down DC-DC converter module to reduced the battery voltage to 5V.
A pendulum stand is going to be our launch tower. So I made some drills on the stand to hold our motor. Let's design and 3D print a holder to attach our motor with the stand and attach the motor and screw it.
Now that we have fixed our stepper motor, Let's attach our BBQ Gas lighter with a ball head clamp. We need to figure out a way to press the trigger.
I don't have a threaded lead screw rod. With that, we could have just attached a screw to press the trigger. But for the time being, I am going to try if the belt mechanism works.
I have only two ball head clamps. I have already used one clamp to hold the lighter, and I am going to use another clamp to hold the rockets. I am going to 3d print a clamp to hold the lighter properly.
Once the lighter is placed in a stable manner, we can attach the belt with the lighter and connect it to the motor pulley.
We have to use the microcontroller to program the time it takes to properly press and release the trigger.
I am going to use the ESP8266 Development board. This board has WiFi functionality. So I can use two of this board to wirelessly control the ignition.
The stepper motor has to be driven by the microcontroller using a specialized driver interface. I am going to A4988 Stepper motor driver controller module.
Step 4: Testing the Ignition System
I have already assembled and programmed the circuit. So let's check if we could press the trigger using the stepper motor.
We shall attach an L-Clamp and wrap it with the motor pulley.
I have very less time to make it work professionally.
This is the crude method but it works.
It's time to build the transmitter circuit.
Step 5: Launch Initiate Side Electronics
This circuit has another ESP8266 controller, A lithium polymer battery, A battery charge controller module, A voltage booster module that converts the battery voltage to 5V, An On-Off switch, An 8 digit segmental LED Display module and a trigger switch to start the countdown timer.
We shall design an enclosure for this transmitter and quickly 3D print it. Let's put the electronics inside it. I have attached a tripod mount screw to it.
Let's attach the display module and glue it. Let's attach the battery and other electronics using double-sided tape.
I have already programmed the microcontrollers. The WiFi transmitter establishes a WiFi connection. Upon successful connection, we shall press the trigger button to start the countdown timer. Actually, the transmitter circuit is configured as a WiFi client, and the ignition system hosts a web server. When the countdown timer reaches 0 seconds, our transmitter will send an HTTP GET request to the server. The server interprets it and starts the ignition process.
Alright. It's time to test it.
Step 6: Launch It!
Let's press the trigger button.
Ahah! It works!!
There is a professional way of doing this. I will write another instructable of it when I find the time.