DIY Remote control car: The best RC car tutorial
Remote control cars have been the dream toy for most kids. And you can never outgrow them! So In this article, I will show you an in-depth step by step procedure on how to make a simple Remote Control Car that operates in RF (radio frequency). This is a very simple and beginner level robotic project which can be made by anyone with interest. I will discuss the working of all integrated circuits (IC) and modules used dor this robot. And the best part for beginners is that there is NO programming required for making this robot!
Things you need
- RF transmitter-receiver module——Amazon.in
- Prototype boards—————————-Amazon.in
- HT12E encoder——————————-Amazon.in
- HT12d decoder——————————-Amazon.in
- L293D Motor driver————————Amazon.in
- 7805 step down regulator—————Amazon.in
- 12v dc motor——————————— Amazon.in
- 12v power supply————————–Amazon.in
Check out my article on How to make Lithium-ion battery pack from old laptop batteries
- Robot Chassis——————————–Amazon.in
First, Both the RF transmitter and receiver circuit requires a separate power supply. The receiver circuit would require 9-12v supply depending upon the motor you are using and the transmitter circuit can be powered using a 9v battery.
Voltage regulator 7805
The 7805 is a linear voltage regulator used to regulate 12v supply to 5v
To this pin, the positive of the unregulated power supply is connected. In my case 12V, It can go up to 35V according to the datasheet
The negative of the Input power supply.
This pin gives regulated positive 5V
Use heat sink for 7805 because we are dropping 7v (12-5 )so lots of heat will be produced to burn the regulator so use heat sink is recommended
What is RF module ?
This RF module consists of an RF Transmitter and an RF Receiver. The transmitter sends data wirelessly and receives it through an antenna. To have a successful transmission both transmitter and receiver should operate at the same frequency. This module is used with a pair of encoder and decoder IC. The encoder is used for encoding data for transmission and in the reception, a decoder is used to decode the received data.
Some features of RF 433Mhz RF Module
- Operating frequency: 434 Mhz
- Operating Voltage : 3~5V
- Data transmission rate: 1Kbps – 10Kbps
- ASK Modulations.
- Low Current consumption (5.5mA at 434MHz)
Working of the Robot
Pin Description RF module
Goes to the ground of the circuit
To this pin data to be transmitted is given, INPUT pin
Power supply for the module, 5V
To this pin, an external antenna can be attached to improve the range, Solder a single strander 20cm long wire to this pin.
This Pin is to connect an external antenna to improve the range, connect 20cm long wire to it
Goes to the ground of the circuit
Power supply for transmitter it can be between 2.5-5V. Recommend 5V for a better range.
There are 2 data pins you can use anyone since both are internally connected. This pin is the output pin of the receiver.
The transmitter circuit consists of an HT12E Encoder IC, an RF transmitter module and a pair of DPDT switch
In the above circuit, you can see A B C D label marked near the switch. In the below DPDT switch wiring illustration also I have mentioned A B C D label. Just connect the label in the transmitter circuit to the label in the DPDT wiring circuit. i.e A –> A, B –> B, C –> C and D –> D
These pins are used to set address, It can be either set open or made high. The address combination should be the same for both Encoder and Decoder.
Goes to the ground of the circuit
These are the input pins. To this pin, we will be connecting the DPDT switches. It be left HIGH or LOW
TE stands for Transmission Enable. This pin needs to be made LOW (Grounded) to enable transmission.
These pins are to connect the external oscillator.
This is the serial output pin. This pin goes to DATA pin of the transmitter module
Positive power supply for the integrated circuit, 5V
Make the Receiver
The receiver circuit has got 2 integrated circuits (ICs) (HT12D decoder, L293D motor driver)and RF receiver module.
Wire the circuit as per the above receiver schematic. There are 2 led in the receiver board, one is power status, this turns ON when the power supply is provided to the receiver circuit. The other LED is connected to pin. This LED will turn ON if the receiver is getting a valid transmission. When the power supply is provided to the transmitter circuit this LED should turn ON, If not there is something wrong with your connection or your RF TX RX module.
Note: Use red wire for positive and black for negative if there is any problem with the circuit it will be easy for debugging the circuit
– This is the address input. Status of these pins should match with the status of the address pin in HT12E (used in the transmitter) to receive the data. These pins can be connected to VSS or left open
– This is the data output pins. Status of these pins can be VSS or VDD depending upon the received serial data through pin DIN.
This pin is the serial data input and can be connected to an RF receiver output.
– This pin is used to connect external resistors for the internal oscillator of HT12D. OSC1 is the oscillator input pin and OSC2 is the oscillator output pin
stand for Valid Transmission. This output pin will be HIGH when valid data is available at D8 – D11 data output pins.
This pin is used to provide power to the IC, Positive and Negative of the power supply respectively:
The L293D is a 1A Motor Driver IC that can drive up to 2 motors in bi-direction. This driver IC is dedicated to controlling the DC motor. It can control a set of 2 DC motors same time in any direction.
If you need more information regarding this integrated circuit please refer to the datasheet here
Pin description of L293D
These pins, when made HIGH, enables the driver channel 1 and 2
Input for the drive channel 1 and 2
Goes to the ground of the circuit and heatsink (if using)
To these pins, the left side motos are to be connected
Power supply pin for the internal logic translation 5V
These pins, when made HIGH, enables the driver channel 3 and 4
Input for the drive channel 3 and 4
To these pins, the right side motos are to be connected
The power supply for the motor goes to this pin. 4.5v-36v
Decide the Motor Specification
Choosing a motor is very important and this totally depends on the type of robot you are building. There are many types of DC motors available with different specifications like the voltage, torque. If you have trouble choosing the motor. I suggest using 12V 200RPM geared motor.
Choose the right RPM for motor
In my case I have a 12V 300 RPM motor RPM, RPM stands for revolutions per minute, It is the number of times the shaft of a DC motor completes a full spin cycle per minute. You should be very careful while choosing the RPM. Don’t go for higher rpm cause it will be difficult to control it since this model of robot doesn’t have speed regulations. Remember SPEED IS INVERSELY PROPORTIONAL TO TORQUE
DEBUGGING (OPTIONAL, If your robot isn’t moving).
In this part, I will be discussing on how to debug the circuit. First of all, don’t be angry, just keep calm. We will go for split and conquer. We will split the circuit into different parts.
For debugging the L293D IC. Place the IC on a breadboard and provide power supply +5v to and Gnd to and connect +12v to pin 8 . Connect a motor to &. Connect both the enable pins & to 5v. Now connect 5v to and connect to the ground of the circuit. If everything is proper the motor should rotate and if the connection to & are inverted the motor should rotate in the opposite direction. Do the same with the other side.
Use a multimeter and put in continuity mode, and check for any short circuit between positive and negative pins. Check if all the ICs are getting proper voltage. Make sure all the GND pins are properly grounded.
Decoder and Encoder (HT12E/Ht12D)
You can check if your decoder and encoder are working properly without using the RF module pair. Connect pin 7 of HT12E to pin 14 of HT12D, Connect push buttons at pin 10,11,12,13 of HT12E and connect 4 LEDs at pin 10,11,12,13 of the decoder ( connect as per Decoder and Encoder Debugging circuit ) The LEDs should light up when switches are pressed
If your robot is still not working then there would be a problem with the RF module and so try replacing the module.