Heidi Wang's Assignment 5: High(er) voltage and transistors

Requirements

• N-MOSFET transistor
• input sensor that uses a library: e.g. remote control, capacitive sensing, humidity sensor
• high-load output device
• external power supply
• analogWrite()

Schematic



The IR receiver is controlled with an IR remote.

Vcc is connected to a 9V DC adapter from main wall power.

Calculations

The 4 LEDs draw 4*1.8=7.2V of voltage out of 9V, with 1.8V drop remaining.

With a 220 Ohm resistor, the current is I=V/R=1.8/220=8.18 mA, which is well below the max continuous drain current for the transistor of 37.2 A at 25 deg C.

Circuit



Firmware

link to code file

        
/*
  Transistors

  with help from
  https://www.circuitbasics.com/arduino-ir-remote-receiver-tutorial/

  The load on the transistor is gradually activated or deavtivated
  whenever the power button on the IR remote is pressed.

  The transistor is connected to pin 10.
  The IR receiver is connected to pin 7.

  2025 November 10
  Heidi Wang
*/

// IRremote version 2.6.0
#include 

// IR receiver pin
const int RECV_PIN = 7;
// initialize receiver object
IRrecv irrecv(RECV_PIN);
// initialize results object
decode_results results;
// transistor load pin
const int loadPin = 10;
// the current state of the load pin
int loadState = LOW;

// setup function
void setup() {
  // begin serial comm
  Serial.begin(9600);
  // enable receiver
  irrecv.enableIRIn();
  // blinks receiver LED when receiving signal
  irrecv.blink13(true);
  // sets load pin as OUTPUT with auto initial value of 0
  pinMode(loadPin, OUTPUT);
  // turn off load for initial state
  digitalWrite(loadPin, LOW);
}

// loop function
void loop() {
    // on receiving input
    if (irrecv.decode(&results)) {
        // print the IR code received
        Serial.println(results.value, HEX);

        //if keypad power button is pressed
        if (results.value == 0xFFA25D) {
          // toggle the load state
          loadState = !loadState;

          // if the new load state is HIGH, then gradually activate the load
          if (loadState == HIGH) {
            // fade in from min to max in increments of 5 points:
            for (int fadeValue = 0; fadeValue <= 255; fadeValue += 5) {
              // sets the value for the load (range from 0 to 255):
              analogWrite(loadPin, fadeValue);
              // wait for 30 milliseconds to see the fading effect
              delay(30);
            }
          }
          // else the new load state is LOW, then gradually deactivate the load
          else {
            // fade out from max to min in increments of 5 points:
            for (int fadeValue = 255; fadeValue >= 0; fadeValue -= 5) {
              // sets the value for the load (range from 0 to 255):
              analogWrite(loadPin, fadeValue);
              // wait for 30 milliseconds to see the fading effect
              delay(30);
            }
          }
        }

        // reset the receiver to receive the next code
        irrecv.resume();
    }
}
        
      

Operation

Questions

1. From the datasheet for the N-MOSFET transistor https://www.diodes.com/assets/Datasheets/DMT6009LCT.pdf, The max current between pins 2 and 3, i.e. Drain and Source, is 37.2 A at 25 deg C.

2. Circuit with Arduino, DC motor, flyback diode, and capacitor:

   

   components:

   • N-MOSFET transistor https://www.diodes.com/assets/Datasheets/DMT6009LCT.pdf
   • DC motor https://medialibrary.dana-industrial.com/wp-content/uploads/Technical-catalogue-Direct-current-motors.pdf
   • flyback diode https://octopart.com/datasheet/p6ke200arlg-littelfuse-80727603
   • capacitor https://octopart.com/datasheet/eeu-fc1h101-panasonic-39478547
   • resistor https://octopart.com/datasheet/cfr100j100r-te+connectivity-16077129
   • Arduino UNO R3 https://docs.arduino.cc/resources/datasheets/A000066-datasheet.pdf

3. The datasheet for the L293D chip: https://www.ti.com/product/L293DLinks

   

   To move motor:

   • A and B both forward,
   • A and B both back,
   • A forward and B back,
   • and A back then A forward:

               
   // Motor A pins
   int enA = 11;
   int in1 = 12;
   int in2 = 13;
   // Motor B pins
   int enB = 6;
   int in3 = 7;
   int in4 = 8;
   
   void setup() {
     // Set all motor pins as OUTPUTs
     pinMode(enA, OUTPUT);
     pinMode(enB, OUTPUT);
     pinMode(in1, OUTPUT);
     pinMode(in2, OUTPUT);
     pinMode(in3, OUTPUT);
     pinMode(in4, OUTPUT);
   
     // Set initial state to LOW
     digitalWrite(in1, LOW);
     digitalWrite(in2, LOW);
     digitalWrite(in3, LOW);
     digitalWrite(in4, LOW);
   }
   
   void loop() {
     // Set motors to HIGH speed
     digitalWrite(enA, HIGH);
     digitalWrite(enB, HIGH);
   
     // A and B both forward
     digitalWrite(in1, HIGH);
     digitalWrite(in2, LOW);
     digitalWrite(in3, HIGH);
     digitalWrite(in4, LOW);
     delay(2000);
   
     // A and B both back
     digitalWrite(in1, LOW);
     digitalWrite(in2, HIGH);
     digitalWrite(in3, LOW);
     digitalWrite(in4, HIGH);
     delay(2000);
   
     // A forward and B back
     digitalWrite(in1, HIGH);
     digitalWrite(in2, LOW);
     digitalWrite(in3, LOW);
     digitalWrite(in4, HIGH);
     delay(2000);
   
     // A back then A forward
     digitalWrite(in1, LOW);
     digitalWrite(in2, HIGH);
     delay(500);
     digitalWrite(in1, HIGH);
     digitalWrite(in2, LOW);
     delay(2000);
   
     // Turn off motors
     digitalWrite(in1, LOW);
     digitalWrite(in2, LOW);
     digitalWrite(in3, LOW);
     digitalWrite(in4, LOW);
     delay(2000);
   }
               
             

4. No AI use.