RF Transmitter and Receiver

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About: Student of Mechatronics

In this project, I will use RF modules with Pic 16f628a. It will be a short tutorial about rf. After you learn ho rf modules communicate with each other you can use these modules with pic microcontroller, ardunio or any microcontroller. I controlled RGB LEDs but If you can control many thing motors or relays.

Step 1: Short RF Lesson

What is RF?

In short term, radio frequency (RF) refers to the rate of oscillation of electromagnetic radio waves in the range of 3 kHz to 300 GHz, as well as the alternating currents carrying the radio signals.

How does it work?

We need two modules which are transmitter and receiver. Our control our data 1 and 0(we use the microcontroller in this project) and transmitter send these data in Seri way in radio waves. After ıt started broadcasting, receiver collect these radio waves and it gives as 1 and 0 again.

Why do we use it?

If we want to communicate some devices without any wire we RF modules is one of the ways.

Step 2: Circuit Schemas

In the first circuit is the transmitter second is receiver.I controlled 3 RGB led by this modules.

Step 3: Component List

Transmitter Part:

  1. pic16f628a
  2. 18pin dip socket
  3. 1n4001 diode
  4. lm7805
  5. 220 uf 16v electrolytic cap
  6. 1 uf cap
  7. 330ohm ^1
  8. 4.7k ohm ^1
  9. Rf transmitter (433 MHZ)

  10. 10k ohm ^4
  11. 4 push button
  12. 5mm led
  13. male header

Receiver Part:

First eight is the same

9.RF receiver (433 MHZ)

10. 5mm RGB led ^3

11.led

12male header

Note:RF modules must be same frequency.

Rf modules link of rf modules

Step 4: Printed Circuit Board

I love using PCB instead of prototype PCB(including many holes), In my opinion, this way is more healthy for circuits. After designing the circuits I printed on the boards but there are some tiny nets so I needed to fix some nets. After fixing operations they go to in acid. Then they are ready for next step.

Step 5: Solder Mask !

Its optional part.

Solder mark has some difficulties but otherwise, it has some benefits.Your PCB can be healthy very long time and short circuit risks become increases.You can find many resources about how can you make solder mask at home.After the solder mask operations, PCB's go drilling operations.

Step 6: Soldering

At last, we soldering the components on PCB. My advice you should solder dip socket first but attach the pics and rf modules after soldering. You should be very careful about short circuits. Besides, rf modules can be effected static electric very easily.

Step 7: Codding

I used PIC CCS for programming. If you have any question about anything just ask it, please.

First, we choose the baudrate you should look that for rf modules datasheet then we define transmitter an receiver pins. Parity is about our data is odd or even but we don't use it in this project, at last, we choose 1 our stop bit.

Preamble Function:

If we try to use the same many RF modules in the same area it will be some provision. We prevent this problem with preamble function. We define an identification for our modules and sent it receiver module.

We can see this function on the oscilloscope.First two pic belong transmitter and second modules belong receiver circuit

Step 8: RUN!

In this project main idea was RF communication thus I did not use qualification pic or oscillator. If you want to obtain better communication you should use high-frequency crystal oscillator and high-frequency RF modules. You should use an antenna.

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    40 Discussions

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    christochandy

    3 months ago

    Very poor description. You didn't clearly given the component list (like IC, Resistor, Capacitor specifications)

    1 reply
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    onion2

    3 months ago

    What do you think about the oscilloscope used in your pictures ? I hesitate to buy one

    And thank you for your article, it's very useful

    2 replies
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    AlphaOmega1onion2

    Reply 3 months ago

    For a scope to keep in your pocket and for the price, they are great. BUT get an original there are many copies that don't work well.

    I was given a kit a few years back. I had a few issues, but the manufacturer was very helpful (and open to suggestions). I don't use it very often, but find it good enough that I don't bother to dust off my Philips CRT scope.

    BTW, a 'scope requires a certain level of skill and knowledge to use and get meaningful results from. But a very powerful tool.

    I also use a USB logic analyser (these are cheap from China) with software that understands many protocols including i2c, making fault finding much easier. Again, a powerful tool that requires understanding to get the most from it.

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    OEsirikonion2

    Reply 3 months ago

    Thank you for good comment.It is not so sensitive but It can shows basic difference of signals,thus I like it.

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    AlC70

    3 months ago on Step 8

    Be aware that 433 MHz is within the LICENSED UHF amateur radio bands. I license is required to use these frequencies (420 - 450 MHz) at any power level. One of the national hobby shops was recently fined several million dollars for marketing drones that use these frequencies and don't warn consumers about the "non type accepted" products. There are exceptions, just be sure to check with your local authorities before transmitting on these frequencies.

    5 replies
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    eburmanAlC70

    Reply 3 months ago

    Seriously? Get of your high horse! These units put out a minuscule signal. It's not enough to even make it outside the walls of my house. What value is there in your comment? You say "check with your local authorities." Which authorities? Are you able to provide so much as one legitimate example of someone who has been prosecuted by the FCC for using one of these units? Citations please.

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    JCFLindsayAlC70

    Reply 3 months ago

    I want to play with ham/SW radio reception. Can you recommend a place for beginners to learn, and how to purchase equipment?

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    JimG50JCFLindsay

    Reply 3 months ago

    For info and books about Amateur Radio (Ham Radio) see ARRL.ORG. For equipment google ICOM, Yaesu, Kenwood or go on Ebay searching for amateur equipment. Or build your own. 73. JIm

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    DavidH1070AlC70

    Reply 3 months ago

    do you have a reference for these rules that a layman could reference?

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    e5frogAlC70

    Reply 3 months ago

    433MHz is a license free band in the EU for low effect (LPD433). In Sweden (possibly wider area, don't know) the allowed band is 433.050 - 434.790MHz and you often find them in cordless headphones, remote light/power switches etc

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    manicmonday

    3 months ago

    I don't understand the schematics with how they are broken up. Can you provide a schematic that is not broken up?

    I want to build a one button with a buzzer that would work as a remote control finder. Would this be good for that? Thanks

    2 replies
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    OEsirikmanicmonday

    Reply 3 months ago

    first schematic is transmitter second is receiver.main difference between them rf modules connection.

    Yeah you can use in my opinion.transmitter part almost same, you change the receiver part.remove the rgb leds and add bjt for buzzer.

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    manicmondayOEsirik

    Reply 3 months ago

    For the 2 parts I would expect to see 2 schematics instead of 7.

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    bluesea8

    Question 3 months ago

    What is the transmitted distance? How far apart can transmitter and receiver be and still communicate with each other?

    1 more answer
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    OEsirikbluesea8

    Answer 3 months ago

    In closed area approximately 3m.But you can obtain better performance if you feed high voltage transmitter (i feed with 5v).

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    snorlaxprime

    3 months ago

    Thank you for the for the instruction, what is the pin on the transmitter module?