Hey guys, in our previous post I showed you the circuit that we will need for the Arduino based RC transmitter and receiver that we are making. However, there was some confusion in the circuit. So, in this post, you can find a clearer circuit of the Arduino transmitter and receiver below and also see the part list I have used in this project. If you want to see the coding, please refer to my previous post here.

Note also that I have made some more changes in the transmitter circuit which I have not shown below. The change is that I have added a buck converter in the circuit to power the NRF module. I was previously using the 3.3V from the Arduino to power the NRF module. However, this was not able to deliver enough current for the NRF with the antenna to work. I am powering the circuit with a 7.4V lipo battery. I have connected the input of the buck converter to the 7.4V battery and then I have adjusted the voltage to 3.3V using the small potentiometer. Once I got the 3.3V, I have connected it to the input of the NRF. Now make sure you always adjust the voltage before connecting it to the NRF else if the voltage is higher than 3.7V, it will blow your NRF. So, it is very important to do it like that.

You can see the picture where you can see I added the buck converter. For more details about it, you can refer to THIS site.

Part lists:
Transmitter

1.  1 Arduino nano (ATMEGA 328P): Link here
2.  2 toggle switch: Link here
3.  2 Joysticks: Link here
4.  1 NRF24L01 module: link here
5.  1 potentiometer: Link here
6.  1 battery (9V) or sets of batteries equivalent to 9V
7.  1 battery holder

Receiver

1.  1 Arduino nano (ATMEGA 328P): 
2.  1 NRF24L01 modules: Link here
3.  2 LEDs: Link here
4.  2 330 ohms resistors: Link here
5.  1 coreless dc motor(7x14): Link here
6.  1 Mosfet P0903BDG: Link here
7.  1 10K ohm resistor: Link here
8.  1 Schottky diode 1N5819: Link here

           NRF24L01 DIAGRAM

    

      Transmitter circuit diagram:


        Receiver Circuit Diagram


Now I am using the Arduino nano for the transmitter because it is very small and will make it perfect for the transmitter to be portable. However, it has a USB port that is made of metal which adds some weight to it. So, if you are making a very light drone, this would probably be a bad choice. For that reason, I am using an Arduino pro mini for the receiver part if I intend to make a drone from this receiver. Arduino pro mini is very light. However, we cannot program it directly using the USB cable. We have to use an FTDI programmer for that. We just have to plug it to the pins of the Arduino and upload the code and you can remove it as soon as the code has finished uploading.

Also, make note of the MOSFET I am using. This type of MOSFET is N-channel. As we are using it to control the speed of a motor, we know that it will draw a lot of currents. The coreless motor that I am using will draw a maximum of 2A which is most of the MOSFETs can handle. However, if you are using bigger size motors, you should always check the continuous current that the MOSFET can handle. Suppose we are using a MOSFET that is rated at 2.5A and we are running a motor that is drawing 2.5A. Our MOSFET will get really hot. If our motor draws even more current than that, it will blow it. So always make sure to check the datasheet before selecting MOSFET.

Now another thing to point out is that we are going to use the PWM signal from the Arduino to control the speed of our motor. You guys must already be familiar with it. If you don’t know about it, then a brief explanation would be that we can control the voltage by switching it on and off very fast. The speed should be around 120 times per second which is almost impossible to do manually or mechanically. So, we use an electronic device for it that acts as a switch to which we have full control and that is MOSFET. Now note that the MOSFET is a function of Voltage, unlike BJT which is a function of current. That means, the higher the voltage we add to the drain, the higher the voltage will be to the gate and source of the MOSFET. PWM signal is used to control the voltage at the drain by controlling its Duty cycle. Now that is a whole topic in itself. We will discuss everything you need to know in another post.

I hope the diagram is clearer now. Put a thumb up on my youtube video and subscribe.