Remote control cars have been the dream the toy for most kids. And you can never outgrow them! In this post, I will show you step by step, 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 be discussing on the working of all integrated circuits (IC) and modules used in this robot. And there is no programming required for making this robot!
Watch the robot inAction 🙂 😀
Stuff you need to make the robot (Rc Car)
- RF transmitter receiver module
- prototype board x2
- HT12E encoder
- HT12d decoder
- L293D Motor driver
- 7805 step down regulator
- 12v dc motor(RPM depends on your choice,i have used 300 RPM)
- 12v power supply
- Robot Chassis (Optional ) or try a DIY chassis 😀
Make the power supply
First we will start with the power supply circuit. Both rf transmitter and receiver circuit need separate power supply The receiver circuit need to powered using 12v supply and transmitter circuit can be powered using 9v battery
- Pin 1 — Input voltage (5v-18v ) [V in]
- Pin 2 — Ground [gnd]
- Pin 3 — Regulated Output (4.8v – 5.2v]
- IC 7805 which regulates the 12v supply to 5v (if cant get a 12v supply you can use a 9v supply)
- 0.1uf & 470uf capacitor
- And 1k resistor for status led
NOTE: 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 consist of an RF Transmitter and an RF Receiver. The transmitter/receiver (Tx/Rx) pair operates at a frequency of 434 MHz. An RF transmitter receives serial data and transmits it wireless through RF through its antenna connected at pin 4. The transmission occurs at the rate of 1Kbps – 10Kbps.The transmitted data is received by an RF receiver operating at the same frequency as that of the transmitter. The RF module is used along with a pair of encoder and decoder. The encoder is used for encoding parallel data for transmission feed while reception is decoded by a decoder. HT12E-HT12D
Working of the Robot
The RF module is used along with a pair of encoder and decoder. The encoder is used for encoding parallel data for transmission feed while reception is decoded by a decoder. HT12E-HT12D
PIN DESCRIPTION RF TRANSMITTER
Pin 1 — Ground [GND]
Pin 2 — Serial Data Input Pin [DATA]
Pin 3 — Power supply; 5V [Vcc]
Pin 4 — Antenna output pin [ANT]
Pin 1 — Ground [GND]
Pin 2 — Serial data output pin [DATA]
Pin 3 — Linear output pin (Not connected) [NC]
Pin 4 — Power supply;5v [Vcc]
Pin 5 — Power supply;5v [Vcc]
Pin 6 — Ground [GND]
Pin 7 — Ground [GND]
Pin 8 — Antenna Input pin [ANT]
Make the Transmitter (Remote)
- HT12E encoder
- RF transmitter module
- Two DPDT switch
- and 1M resistor
You can see i have marked A, B, C, D in the transmitter circuit after the switch and see the DPDT connection diagram below there also you can see i have marked A, B, C, D. Connect A,B,C,D on the transmitter circuit to A,B,C,D on the 2 DPDT switch.
The DPDT switch connections is shown above.
HT12E PIN DESCRIPTION
Pin (1- 8) — 8 bit address pin for output [ A0,A1,A2,A3,A4,A5,A6,A7 ]
Pin 9 — Ground [ Gnd ]
Pin (10,11,12,13) — 4 bit address pin for input [ AD0,AD1,AD2,AD3 ]
Pin 14 — Transmission enable , Active low [TE]
Pin 15 — Oscillator input [ Osc2 ]
Pin 16 — Oscillator output [ Osc1 ]
Pin 17 — Serial data output [ Output ]
Pin 18 — Supply voltage 5V (2.4V-12V) [ vcc ]
A0-A7 — These are 8 bit address pin for the output.
GND — This pin should also be connected to the negative of the power supply.
TE — This are the transmission enable pin.
Osc 1,2 — These pins are the oscillator input and output pins.This pin are connected to each other with a external resistor.
Output — This is an output pin. The data signals is given out from this pin.
Vcc — The Vcc pin connected to positive power supply, It is used to power the IC.
AD0 – AD3 — These are the 4 bit address pins.
PIN DESCRIPTION FOR HT12D VDD and VSS: This pin are used to provide power to the IC, Positive and Negative of the power supply respectively
DIN: This pin is the serial data input and can be connected to a RF receiver output.
A0 – A7: This are the address input . Status of these pins should match with status of address pin in HT12E (used in transmitter) to receive the data. These pins can be connected to VSS or left open
D8 – D11: This are the data output pins. Status of these pins can be VSS or VDD depending upon the received serial data through pin DIN.
VT: stand for Valid Transmission. This output pin will be HIGH when valid data is available at D8 – D11 data output pins.
OSC1 and OSC2: This pin are used to connect external resistor for internal oscillator of HT12D. OSC1 is the oscillator input pin and OSC2 is the
oscillator output pin
L293D (Motor Driver)The L293D is a Motor Driver IC it allows the motor to drive on both direction. L293D is a 16-pin IC with eight pins, on each side, dedicated to the controlling of a motor which can control a set of two DC motors at a same time in any direction. With one L293D we can control 2 dc motors ,There are 2 INPUT pins, 2 OUTPUT pins and 1 ENABLE pin for each motor. L293D consist of two H-bridge. H-bridge is the simplest circuit for controlling a low current rated motor.
PIN DESCRIPTION OF L293D
Pin 1 — Enable pin for motor 1 [Enable 1 ]
Pin 2 — Input pin 1 for Motor 1 [Input 1 ]
Pin 3 — Output pin 1 for Motor 1 [Output 1]
Pin 4,5,12,13 — Ground [ GND ]
Pin 6 — Output Pin 2 for Motor 1 [ Output 2 ]
Pin 7 — Input pin 2 for motor 1 [ Input 2 ]
Pin 8 — Power supply for motors(9-12v) [Vcc]
Pin 9 — Enable pin for motor 2 [ Enable 2 ]
Pin 10 — Input pin 1 for motor 1 [Input 3 ]
Pin 11 — Output pin 2 for motor 1 [Output 3]
Pin 14 — Output 2 for motor 1 [ Output4 ]
Pin 15 — Input 2 for motor 1 [ Input 4 ]
Pin 16 — supply voltage ; 5V [ Vcc1 ]
Choose the right motor
Choosing a motor is very important and it totally depends on the type of robot (car) you are making if you are making a smaller one use 6v Bo motor If you are making a larger one which need to carry heavy load then use an 12v dc motor
CHOOSE THE RIGHT RPM FOR MOTOR
I have 12V 300 RPM motor RPM, which stands for revolutions per minute, is the amount of times the shaft of a DC motor completes a full spin cycle per minute. A full spin cycle is when the shaft turns a full 360°. The amount of 360° turns, or revolutions, a motor does in a minute is its RPM value. You should be very careful while choosing the rpm don’t choose motors of higher rpm cause i will be difficult to control it and remember SPEED IS INVERSELY PROPORTIONAL TO TORQUE
DEBUGGING (OPTIONAL, if there is problem with circuit)
In this session i will be discussing on debugging the circuit First of all don’t be angry just keep calm for debugging we will split the circuit in different First we will be debugging the
Place the IC on a bread board and give 5v and Gnd to the IC and then give the 12v to pin 8. connect the enable pins of the motors to 5v .Now give power to the input of one motors and check the output pins with a multimeter. If it shows nothing then there is problem with you motor driver
Most of the problems arise in the power supply circuit is due to short circuit so for checking power off the circuit and use a multimeter to check whether there is any connection between Negative and positive
DECODER AND ENCODER(HT12E/Ht12D)
For debugging the decoder and encoder IC 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 [fig 3]) The leds should light up when switches are pressed
If your robot is still not working then there would be problem with the RF module and so try replacing the module.