Introduction: Arduino Transistor Tester

now days you can get transistor tester which can also test other components like resistor,capacitor,inductor,etc.but why to spend some much if you want to know are your transistor are fine so in this instructable I will show you how to make a arduino transistor tester

Note:This works with only NPN Transistor

Step 1: Things Needed

Things required for the project are

  • Arduino (any type)
  • Resistor(1k)
  • Resistor(x2)(220)
  • Red LED
  • Green LED
  • Working Transistor(optional just for helping);

Step 2: Connect the Component on a Breadboard

  • connect gnd to negative rail of breadboard
  • connect collector of transistor to gnd
  • connect 1k resistor to base of resistor
  • connect other side of 1k resistor to pin 2
  • connect emitter of transistor to pin 3
  • connect green LED positive to 220 resistor
  • connect other leg of 220 resistor to pin 13
  • connect the green led negative to gnd
  • connect red led negative to 220 resistor
  • connect the other end of the 220 resistor to gnd
  • connect the red led positive to pin 13
  • done now to the code

Step 3: Code

Now Write the code. The code is in bold

void setup() {






void loop() {

digitalWrite(2,HIGH); if(digitalRead(3)==LOW){



Serial.println("Transistor is working");






Serial.println("No transistor or the transistor is broken");




Step 4: How to Know It Works

If you place a transistor(working one) then the green led should light up

if not then then red led should light

Step 5: Sucess

If you done it right then congrats you made now no more transistor tester

thanx for reading my instructable

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