How to make an RF transmitter and receiver with HT12E and HT12D
Ora pubblicata: 2020-12-01 17:26:10
How to make an RF transmitter and receiver with HT12E and HT12D? This requires solid theoretical knowledge and strong hands-on ability. Below, Jotrin will introduce it in detail. Reminder: This article contains a lot of pictures, please connect to WIFI on your mobile phone or read it on your computer.
Purpose: Use HT12E and HT12D to make a simple RF transmitter
We can see from the schematic diagram that this circuit is very simple, but many people have encountered difficulties in inductance.
So the focus of this article is to introduce the winding method of the inductor coil.
The schematic says: L2 should make five turns on an object [length 49 mm width 18 mm]
So please think about it, how long is the enameled wire?
Therefore at least 670 mm enameled wire is required
And then see L1
Need to use 0.57 covered wire to make 103 turns around the second turn of L2
Then the second turn of L2 should be 49+49+18+18
About 13 cm after rounding
Then you should start winding at 13 cm of the 1 mm enameled wire
For example:The last step is optional because the position can be moved after L1 is wound.It should look like this after winding
Move L1 to 13 cm on the 1 mm enameled wire
Then wind L2
Anything of the same size can go around
I also made a mold,Then take it out.
Then connect the coil
If unsuccessful, swap both ends of L1
It is better to connect a microhenry inductance in series with the power supply for better effect. The production method is as follows:
Use 1 mm enameled wire to wind 25 turns on a screwdriver and take it off.
Change the circuit
Microwave Oven L: I have explained the principle thoroughly.
After the electrons are emitted from the cathode, they will bend under the action of the permanent magnetic field. The fewer bends hit the anode, and the larger bends fold back to the cathode.
Adjust the cathode and anode DC electric field strength, the permanent magnet's magnetic field strength, etc. so that the emitted electrons are in the intermediate state of "bumping" and "returning", that is, the critical state and the electrons revolve around the cathode.
The slit of the resonant cavity is equivalent to a capacitor, and the circular cavity is equivalent to an inductance around a loop, which together forms a parallel LC oscillator, and its natural frequency is determined by the mechanical size.
Once the magnetron is energized, some electrons hit the resonant cavity and cause a weak oscillation.
This weak oscillation will generate a high-frequency alternating electric field at the slit as the capacitor. Well, this electric field will regularly superimpose with the critical electric field described in the previous two items.
Therefore, the superimposed electric field effect is regularly strengthened and weakened, which will attract and repel the electrons that were originally in critical flight, and the absorbed electrons will generate a current in the resonant cavity, which supplements the energy of the oscillator and maintains oscillation.
That is to say, the energy of the fast electrons generated by the DC electric field is regularly replenished into the oscillator and becomes microwave energy.
The simplest RF transmitter circuit diagram
This is probably the simplest radio transmitter you will find anywhere. It consists of five parts in total and can be constructed into a very small space. This is a great science fair project or other science-related projects, short-distance transmission is very useful.
It runs from 1.5 to 3 volts, an ideal cell for small hearing aid batteries or lithium "coins". You can insert a thermistor or photoresistor in series with R1, with different output frequencies depending on the input.
The frequency can also be changed by changing the value of C1. Recommend a 2N2222 transistor, but you can also try other types. Performance is often different types of inputs, and from transistor to transistor. L1 is a non-conductive form of thin magnet wire with 20 to 30 turns (24 to 32 Ga) wound close to 1/8 to 1/4" diameter. The coil is tapped in a 1/3 way from the tap at one end to the launch of Q1 Extremely. Experiment with all the values in the circuit. Nothing is important, but performance can vary greatly.
For more RF and wireless information, click here.
How to make a simple radio frequency remote control car
Step 1`2: Preparation
Step 3: Required materials
RF transmitter-receiver module
Prototype board x2
L293D motor driver
7805 buck regulator
470uf capacitor x 2
0.1ufcapacitor x 2
12v DC motor (RPM depends on your choice, I used 100RPM)
12v power supply
dc power jack x2 (optional)
The required materials can be found here.
Step 4: Power
Two RF transmitter-receiver circuits require a separate power supply
The receiver circuit needs to be powered by a 12v power supply, and the transmitter circuit can be powered by a 9v battery
First, we will start with the power circuit. The power supply is the simplest one. The power circuit is composed of
It is composed of IC 7805, which adjusts the 12v power supply to 5v (if 12v power supply is not available, you can use 9v power supply)
0.1uf and 470uf capacitors
And 1k resistor for the status LED
Note: Use the radiator 7805, because we have reduced the 7v (12-5) so much, it will generate heat to burn the regulator, so it is recommended to use the radiator
7805 IC pin description
Pin 1-input voltage (5v-18v) [V in]
Pin 2-ground [gnd]
Pin 3-regulated output (4.8v-5.2v)
Step 5: What is an RF module?
This RF module consists of a radio frequency transmitter and a radio frequency receiver. The working frequency of the transmitter/receiver (Tx/Rx) pair is 434
MHz, the radio frequency transmitter receives serial data and transmits it wirelessly via radio frequency through an antenna connected to pin 4. The rate of occurrence is 1Kbps-10Kbps. Received by the RF receiver of the same frequency as the transmitter.
The RF module is used with a pair of encoders and decoders. The encoder is used to encode parallel data for transmission feed, while the receiver is decoded by the decoder. HT12E-HT12D
Pin 1-Ground [GND]
Pin 2-serial data input pin [DATA]
Pin 3-power supply;
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]
Step 6: Transmitter circuit
The transmitter circuit is composed of HT12E encoder and RF transmitter module.
I have two DPDT switches And 1M resistor
I have 2 sending circuits, one with a DPDT switch and the other with a button
HT12E PIN DESCRIPTION
Pins (1-8)-output [A0, A1, A2, A3, A4, A5, A6, A7] 8-bit address pins
Pin 9-Ground [Gnd]
Pin (10, 11, 12, 13)-4 bit input [AD0, AD1, AD2, AD3] address pins
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-power supply voltage 5V (2.4V-12V) [vcc]
A0-A7-These are 8-bit address pins for output.
GND-This pin should also be connected to the negative pole of the power supply.
TE-this is transmission
Osc 1,2-These pins are the input and output pins of the oscillator. Connect this pin with an external resistor.
Output-This is an output pin. The data signal is sent out from this pin.
Vcc- is connected to the Vcc pin of the positive power supply and is used to power the IC.
AD0-AD3-These are 4-bit address pins.
Step 7: Receiving circuit
The receiver circuit includes 2 ICs (HT12D decoder, L293D motor driver), RF receiver module
The wires follow the circuit of the receiver schematic
There are 2 LEDs on the receiver board, one is on when power is supplied to the receiver, and the other LED is on when power is supplied to the transmitter circuit
If there is no problem with your connection or the RF TX RX module, the LED near the IC HT12D should light up when the transmitter is powered on.
Note: If there is a problem with the circuit, the positive pole is black and the negative pole is black, which will make it easy to debug the circuit
HT12D PIN description
Pins (1-8) 8-bit address pins, used to output [A0, A1, A2, A3, A4, A5, A6, A7]
Pin 9-Ground [Gnd]
Pin (10, 11, 12, 13)-input [AD0, AD1, AD2, AD3] 4-bit address pins
Pin 14-Serial data input [Input]
Pin 15-Oscillator input [Osc2]
Pin 16-Oscillator input [Osc1]
Pin 17-effective transmission [VT]
Pin 18-power supply voltage 5V (2.4V-12V) [vcc]
HT12D pin description
VDD and VSS: This pin is used to supply power to the positive and negative poles of the IC, respectively.
DIN: Connect to the RF receiver output.
A0–A7: This is the address input. The state of these pins should match the state of the address pins in the HT12E (used in the transmitter) to receive data. These pins can be connected to VSS or left floating
D8–D11: These are data output pins. The state of these pins can be VSS or VDD, depending on the serial data received through pin DIN.
VT stands for effective transmission. When there is valid data on the D8–D11 data output pins, this output pin will be HIGH.
OSC1 and OSC2: The external resistance of the HT12D internal oscillator. OSC1 is the oscillator input pin, OSC2 is the oscillator output pin
L293D is a motor driver IC, which allows the motor to continue to drive bidirectionally. L293D is a 16-pin IC with 8 pins on each side, dedicated to controlling a motor, which can simultaneously control a group of two DC motors in any direction. Using an L293D, we can control 2 DC motors, each motor has 2 INPUT pins, 2 OUTPUT
Pins and 1 ENABLE pin. L293D consists of two H bridges. The H-bridge is the simplest circuit to control a low-rated current motor.
Pin function name
Pin 1-Enable the pin of motor 1 [Enable 1]
Pin 2-input pin 1 of motor 1 [input 1]
Pin 3-output pin 1 of motor 1 [output 1]
Pin 4, 5, 12, 13-grounding [GND]
Pin 6-output pin 2 of motor 1 [output 2]
Pin 7-input pin 2 of motor 1 [input 2]
Pin 8-the power supply of the motor (9-12v) [Vcc]
Pin 9-enable the pin of motor 2 [Enable 2]
Pin 10-input pin 1 is used for motor 1 [input 3]
Pin 11-output pin 2 for motor 1 [output 3]
Pin 14-output 2 of motor 1［Output4］
Pin 15-input 2 of motor 1［input 4］
Pin 16-supply voltage; 5V [Vcc1]
Step 8: Select the motor
Choosing a motor is very important, and if you want to make a smaller robot, it all depends on the type of robot (car) being made
Use 6v Bo motor
If you want to make a bigger machine to carry more weight, please use a 12v DC motor
Choose the speed for your motor
RPM, which stands for revolutions per minute, is the number of times the shaft of a DC motor completes a complete rotation cycle per minute. A complete rotation period refers to a complete 360° rotation of the shaft. The 360° rotation or rotation of the motor completed in one minute is its RPM value
Be very careful when choosing rpm, do not choose a higher speed motor, because it is difficult for me to control it, and remember that speed is inversely proportional to torque
Step 9: Carry out the case
Making the chassis is very simple, just need to do two things
Cardboard, a piece of wood or any thick plate used to make the base, and some screws
Pick up the board, place the clip on it, and mark the position of the hole to be inserted into the screw
At the four corners
Tighten the fixture
Insert the motor into the fixture,
Place the circuit on the rack and connect the motor to the circuit
Provide 12v power to the circuit
For details, please check the photo
Step 10: Debugging is optional (if there is a Pr circuit obstacle)
In this part, we will discuss the debug circuit，If you are interested in debugging the amplifier PT2399, you can take a look at it.
Don't get angry first, just keep calm
For debugging, we divide the circuit into different
First, we will debug L293D IC
Place the IC on the breadboard, connect 5v and Gnd to the IC, and then connect 12v to pin 8. Connect the enable pin of the motor to 5v. Now supply power to the input of a motor and check the output pins with a multimeter. If there is no display, there is a problem with your motor driver
Most of the problems in the power circuit are caused by short circuits, so check that the circuit is powered off and use a multimeter to check if there is any connection between the negative and positive
Decoder and encoder
For debugging the decoder encoder IC, connect pin 7 of HT12E to pin 14 of HT12D, connect the button to pins 10, 11, 12, and 13 of HT12E, and connect to pins 10, 11, and 12 of decoder, 13 connect 4 LEDs (according to the decoder and encoder debugging circuit when the switch is pressed, the indicator light should light up.
If your robot still does not work properly, there may be a problem with the RF module, we can debug it, so please replace the module.
Precedente: Amplifier PT2399 debugging guide