Control 7407, hex buffer / driver, using ARDUINO

          Before starting this please read my tutorial on the basics of controlling 7407 using switch.      

          We have already seen, the basics of controlling 7407 using switch. Here we will control 7407 Hex buffer/driver using arduino. Main difference between these two methods is the mode of input voltage supply. In this method input voltage is supplied using Arduino. So 7407 can be controlled using programs. But in older method, we used switches. This method of controlling is manual.

          Circuit is done as shown in the following diagram. 7407 is shown by a rectangle in this circuit. Input pin of the 7407 IC ( any input pin can be used. Here I used 1A ( Pin 1 ) of 7407 ) should be connected to any digital output pin of arduino. I used 13th digital output pin of arduino. Gnd pin of arduino should be connected to the Gnd pin of 7407 IC. Role of pull up and pull down resistors had already explained in my previous tutorial.

Pinout diagram of 7407 hex buffer/driver.

Truth Table of the circuit.

          We have already seen that output function of 7407 is Y = A. That is, output will be HIGH, if the input is HIGH and output will be LOW, if the input is LOW. Truth table is given below.

Program

Upload the following program to your arduino board.

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int led = 13;

// the setup routine runs once when you press reset:
void setup() {              
  // initialize the digital pin as an output.
  pinMode(led, OUTPUT);    
}

// the loop routine runs over and over again forever:
void loop() {
  digitalWrite(led, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(1000);               // wait for a second
  digitalWrite(led, LOW);    // turn the LED off by making the voltage LOW
  delay(1000);               // wait for a second
}

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Working of Circuit.

          When a HIGH voltage is applied from arduino, voltage will drop across the 10K pull down resistor and this voltage will appear across the input pin of 7407 and ground ( HIGH ). This high voltage will create a high impedance in the logic gate buffer. So the output voltage ( Voltage from 30V source ) will appear across the pull up resistor and load. So output current will flow through the pull up resistor to load. That is output will be HIGH, if the input is HIGH. Here load is an LED. This current will not enter the logic gate buffer because of high impedance of logic gate buffer.

          When a LOW voltage is applied from arduino, voltage across the input pin of  7407 and ground will be LOW. This LOW voltage will create a low impedance in the logic gate buffer. So the load current will flow through the logic gate buffer and pull up resistor to ground. So voltage across the load will be LOW. That is output will be LOW, if the input is LOW.
Output

If the circuit is correct and the uploading is successfull, LED will blink in one second delay.

Read more :

Simple Method to Control 7407, hex buffer/driver with 30V open collector outputs, using Switch.

Control 7407, hex buffer/driver with 30V open collector outputs, using ARDUINO.