The drones are very good toys and tools, but usually they haven't any extra skills. I love to fly any R/C model and I just wanted to make a R/C drone that's a little bit smarter than the usual models. That's why I developed this mini voice controlled tricopter robot. The main concept is pretty easy, the drone is based on an Arduino Pro Mini board, the motors can be controlled through PWM pins. I made a bluetooth connection with my Android smartphone and using an app the phone transmits words through serial communucation to the HC-05 bluetooth module to the Arduino board. The best thing is that this project didn't costs more than 11 dollars.

I made a "motor shield" or something like that using a few transistors that increase the current of the digital output pins. I used 2N2222, but would be better to use a SMD power transistort. The drone works well with both. The propellers and the motors are bought from eBay.

Some features:
• speech controlled
• Arduino Pro Mini based
• voice recognition with a smatphone
• moves left, right, backward, forward, upand down
• hasn't build in gyroscope, you should make a code that holds the drone in balance, this can be made after a few experiments
• low weight, 22 grams, you can add 5 extra gramms

I made a tricopter because I have only 3 motors with propeller, but of course you can make a quad or hexcopter.
You'll need some experience in soldering, but isn't so hard. Only the motor shield requires some skill.

Step 1: The Sofware

Before gathering materials write upload this code to your Arduino Mini Pro. If your drone is made perfectly this code will work. If isn't you should modify the code at the end. To programm the Arduino Mini I used an Arduino Uno that was set on 3.3 volts.

1. Arduino Mini Pro to Arduino Uno

2. RX --> TX
3. TX --> RX
4. VCC --> 3.3v
5. GND --> GND
6. RST --> RST
Now upload the code and you'll have a programmed board. I wrote some explanations in the sketch, but if you have questions feel free to ask. The Arduino analyzes the word through serial reading and reacts to them.

Step 2: How the Code Works?

The code is relatively simple. Analyzes the voice variable and reacts to them by controlling the motors. After turning left or right the Arduino quickly changes its value to the original, so your drone doesn't need a gyroscope, because automatically turns back in his oroginal position thanked to the sofware. This makes your flight safe and fun. :)

//copy this code in the IDE
<p>String voice;<br>int motor1 = 3; //Connect motor 1 To Pin #3 left motor
int motor2 = 9; //Connect motor 2 To Pin #9 rear motor
int motor3 = 11; //Connect motor 3 To Pin #11, right motor</p><p>//--------------------------Call A Function-------------------------------//</p><p>//the values after each anlogWrite commands are controlling the motor's speed, the max value is 255</p><p>//if your drone isn't in balance try to modify the values, example change 130 to 135 if your drone goes backward </p><p>void middlespeed() {
  analogWrite(motor1, 130);
  analogWrite(motor2, 130);
  analogWrite(motor3, 130);
void fastspeed() {
  analogWrite(motor1, 255);
  analogWrite(motor2, 255);
  analogWrite(motor3, 255);
}</p><p>void lowspeed() {
  analogWrite(motor1, 100);
  analogWrite(motor2, 100);
  analogWrite(motor3, 100);</p><p>}
void setup() {
  pinMode(motor1, OUTPUT);
  pinMode(motor2, OUTPUT);
  pinMode(motor3, OUTPUT);
void loop() {
  while (Serial.available()) { //Check if there is an available byte to read
    delay(10); //Delay added to make thing stable
    char c = Serial.read(); //Conduct a serial read
    if (c == '#') {
      break; //Exit the loop when the # is detected after the word
    voice += c; //Shorthand for voice = voice + c
  if (voice.length() > 0) {
    //----------Control motors----------//
    if (voice == "*start motors") {
      lowspeed(); //The motors start spin, and the drone slowly comes downer if already flies
    else if (voice == "*fly low") {
      middlespeed(); //Fly the drone, stay in one place
     else if (voice == "*fly higher") {
      fastspeed(); //Maximum motor speed, the drone will go upward very fast
    }</p><p>    //----------Directions----------//
    //The drone can be controlled the best in middlespeed state
    else if (voice == "*go left") {
      analogWrite(motor1, 100);
      analogWrite(motor1, 130);
    else if (voice == "*go right") {
      analogWrite(motor3, 100);
    else if (voice == "*go backward") {
      analogWrite(motor2, 100);
      analogWrite(motor2, 130);
     else if (voice == "*go forward") {
      analogWrite(motor2, 200);
      analogWrite(motor2, 130);
     else if (voice == "*right back") {
      analogWrite(motor1, 200);
      analogWrite(motor1, 130);
     else if (voice == "*left back") {
      analogWrite(motor3, 200);
      analogWrite(motor3, 130);
    }</p><p>    //-----------------------------------------------------------------------//
    voice = "";
} //Reset the variable after initiating</p>

Step 3: Parts and Tools

For this project you'll need a soldering iron, a glue gun, a variable power supply unit and a PC with Arduino IDE.


Main, most important parts:
Arduino Pro Mini 3.3v clone, but it's better to buy the original Arduino Mini 05 board
3 Motors
HC-05 Bluetooth Module

Secondary parts:
• 2N2222 transistors (local hobby-shop, $0.1)
• 3 Propeller Blades (you can buy together with the motors)
• A Battery (mine is from an MP3 Player)
• Straws and a small lightweight plastic piece (from any store)
• Rubberbands (from a store)
• 100Ohm resistor (local hobby-shop, $0.05)

• Some Wires (local hobby-shop or salvage from other electronic stuff)

You can buy all main parts on the eBay. Click on it to open the link.

Step 4: Soldering...

  • Arduino Mini Pro to HC-05
  • RX --> TX
  • TX --> RX
  • VCC --> 3.3v
  • GND --> GND

Solder the two circuits together using short wires. It's very easy.

Step 5: How to Build the Tricopter's Frame?

Insert the motors in the bigger straws and glue a frame with the other straws, just like on the pictures. I bought very strong straws from a local supermarket and they hold the motors very strong, so they won't fall down. Behind the design are a lot of physics calculations. I can't explain these now formulas and rules but if you're interested read this article. Using those formulas given in link, you can design an own frame and drone.

Step 6: The Rear Motor

You need to make a small difference between the vertical axis and the rear motor's axis otherwise the drone will spin. 10 degrees are enough for this.

Step 7: Motors

You can see some metal sticks on the first picture, I plugged them into the endings of the motors. This is important, because you'll have a joining piont for soldering.

Step 8: Check the Polarity!

On the pictures you can see how my motors should spin. I used my PSU unit and tried out every motors on 2.1 volts.

Step 9: The "motor Shield"

Now you should make a small circuit that can be easily attached to the Mini Pro board. The circuit schematic shows you the connections but I missed the 10kOhm resistor because its value is too high, so it's better to use 100Ohm resistors. This circuit should be very small. Solder connection legs to the 9, 3, 11, GND and VCC pins just like me.

On the schematic are corrected the RX and TX with red font color.

Step 10: Soldering the Transistors

The appearence of this circuit is bad, but it's small and has a low weight. I soldered one more connector for the battery.

Step 11: Adding the Motors

And now it's time to use your soldering skills to solder the motors to the positive voltage source and to theirs transistor's collector. Sorry I haven't more pictures for this step, but I hope it's clear what should you do.

Step 12: The Done Circuit

The harder part is done. We are close to finish the project. Take your Arduino board and slowly connect to the motor shield. Be careful, do not damage or shortcircuit the circuits. Connect the battery to the device, and if the circuit's power LED lights you did a good job. :)

Step 13: Stabilize the Circuit!

Use two rubberbands and fix the circuit on the frame.

Step 14: The Application

Download this application from the Playstore: BT Voice Control for Arduino. Charge up your battery with a PSU or with a lithium polymer battery charger. If you're done try it out.

Step 15: First Flight

As you can see at the first time I din't flew very good, but later after an hour of practice I became a good pilot. Sorry for the bad pictures, but the drone moved in the air. I crashed a few times, but nothing happened with my new gadget.

Step 16: How to Balance in the Air?

If your drone can't stay in one place in the air modify the analogWrite values in the code.

Step 17: Video

This video is made by a $5 Keychain Car Camera and has a very bad resolution and date is bad too: 2012... I don't know why. But you can see how the drone flew up the came down. The commands cannot be heard because of the very bad microphone of the camera. And wasn't very stable, because of the weight of the camera, so I can't move right or left in this video, only up, down, and forward.

Step 18: The End

Thanks for watching! If you liked don't forget to give me a kindly vote. I really hope you'll enjoy to build this drone, it's very fun to make and to fly with this gadget.

<p>you can use fritzing software for building the circuit diagram</p>
How do you charge the battery? do you disconect it, charge it and then connect it again?
<p>Please can anyone tell me where the (+ve) wires of all the motors are to be connected. And also if the transistors are heating up as others have mentioned, what are the alternatives that i can use instead of those. I am new to this and would really like your advice. Thanks</p>
<p>try bc108 metal package transistor they are good in condition of heat</p>
<p>How do you know if I have uploaded the code correctly onto my pro mini board?</p>
<p>Great project! We're are trying to build 2 drones with our students, based on your project but we bumped into a problem: we got 5v arduino pro mini boards. Can the project be adapt to it? If yes, any suggestion on how?</p><p>Thanks</p>
<p>What transistor and what resistor must I use if my arduino pro mini is 5V rather than 3.c volts? what </p>
<p>The diagram of the circuit and the pictures of the circuit look very different to me. It mentions that in the step, but it does not make sense to me. The diagram shows a resistor connected to the base of each transistor, but the picture shows a single resistor connected to either the positive or negative input from the battery. Can someone tell me if I should use the diagram or the pictures when making this project?</p>
I am a beginner can you please say what are the triangle with +mark connect to motor
<p>haha dude in my childhood i was also same as you those traingles are vcc it mean they are positive supply from the battery all the triangle will connet to each other</p>
The motors and propellers arent available on eBay. ANy idea if theres a website where i can order them from?
<p>aliexpress.com free shippin available there at low cost</p>
could u please tell me the specifications of the motor which can be used in it??<br>
<p>the motor have used here are coreless motor they are small in size and you have to buy them with your own reqirements</p>
what should be the code if im using 4 motors?
<p>no problem if you're using four motor it will increase one more transistor and you need to define it in code that on which pin you are going to connect it..</p>
I need arduino pro mini 3.3 v o,motors and HC 05 bluetooth module....<br>I m from bangladesh ...how can i bue those?????
<p>you can try aliexpress there you can find any electronic component and module with free shipping facility or you can try in Dhaka and find there an electronic supplier or whole seller</p>
<p>Is the code still the same if i'm using mosfet transistor as a switch?</p>
<p>yes it based on what is your logic</p>
<p>hey iam new can anyone say how to copy code in aurduino</p>
<p>hey hello what type of code you want to copy just paste loop code in loop section and setup code in void setup ()</p><p>for any further detail related to arduino contact me on my whatsapp +917351233622</p>
<p>how do you charge the battery btw </p><p>i have to disconect it from the arduino and then charge it how do you do it?? </p><p>for some reason it would not let me post comment with out image this is my first draft i do not have a picture of my finall product </p>
<p>HI im still new with the drone things. can i know how to control the drone and how we gonna charge the battery??</p>
where to connect the diode plz tell
<p>Just completed the basics of this build, all of the motors are working and respond to voice. However, it doesn't seem to get nearly enough speed to achieve flight. I know that there's a lot I can still do to get it stable and to reduce the weight (see photo if you don't believe me :) ). But even given that, I don't see this thing getting enough lift. I tried with a few different freshly-charged 3.7v batteries. I suspect that the issue might be the fact that I used one resistor per motor (per OP's schematic) instead of one for all three (per OP's photos)? I'll try taking the extra two out later.</p><p>Any other advice anyone has would be appreciated. Also the transistors did get very hot, very quickly as others mentioned.</p>
<p>Great!! You may change the transistors to some high power transistorts, hopefully that will help you!</p>
<p>dude,if my lipo bat went fat?what should I do shall I continue?it almost double its own size</p>
can u pllzz talk me on whatsapp 8791142427<br>i have bldc motors instead of coreless motor
<p>Hai</p><p>Fantastic project thank you for sharing it with us</p><p>I tried the program (Voice Controlled Drone with LEDs as motor) when I start the following text to the monitor <strong>* starter motors</strong>, all motors start (or all the LEDs light up) Now the question is if I type <strong>* starter motors #</strong> the motors dont stop, what I'm doing wrong, as described Exit the loop when the # is detected after the word </p><p>Can you please help me</p><p>Kind regards</p>
eBay has deleted the listing, can you tell me the motors specification ?
6x16mm motors can be used ??
What is it that you used in the centre? Is it thermacoal?
<p>can you answer me more information about Motor and Propeller, please</p>
<p>wait i have a question.sone blank pcb i saw have no straight copper connection yours is diffrent so does it work diffrently?</p>
Immediately reply when seen........ Hey could you pls tell where to connect the ground from the emmiter of the transistor to the arduino and also the positive end from motor to arduino???? Could u pls tell where to connect the pins... In
<p>i meant straight copper connection</p>
<p>Its a dot board man </p><p>it uses the soldering lead for connection</p>
<p>thx for the info,but I'm still confused.Theres a blank pub with some straight lines that needs to be drill to stop current flow while some is exactly like the pcb that is used here</p>
<p>what can I do to increase the thrust of my quadcopter??</p><p>does shifting the propellers inwards will help? </p>
Ok now I am successfully run motor in full speed but my 2n2222 transistor getting too hot. I used 100ohm resistor for each motor and use 3.7v power from 720mah lipo battery.I tested only one motor on that power.
can you please send the command to fly
<p>In the schematic diagram you have shown for each transistor base input a separate 100ohm resistor is needed but in the motor driver made by you only one single resistor has been used. Please help me I didn't understand how you connected the resistor</p>
Not working. I used arduino nano and 3.7v battery. 2n2222 transister and 100ohm resistor. But my motors didn't run in full speed also transister getting very hot.
I wanted to make this bt before i start , please tell meif it work properly or not
<p>Very good contribution broder, congratulations.</p>
And I also want to know do you made successfully this drone with arduino ?
Yes I tryied already 3 100ohm resistor and also with 1000ohm resister.I think its not possible to run three motors with arduino nano.

About This Instructable



Bio: Hi, I'm Tamas (Thomas), a 17 years old Hungarian guy. My hobby started more than 10 years ago. I learn electronics, physics, programming, IoT ... More »
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