Digital Transistor Identifier




About: I'm a undergraduate student in London metropolitan university and i following my degree (software engineering).

How to identify a transistor whether it is NPN or PNP? This is the easiest way to do it. In this project I'm going to tell how to make transistor identifier using Arduino UNO r3.

What are the information you can get ?

  1. Type of transistor (PNP or NPN)
  2. What are the semiconductors the transistor pins are connected inside in the transistor.
  3. Transistor is working properly or not.

Step 1: What You Need?

3 X 1K resistor

1 X male header (4 pin)

1 X female header (3 pin)

1 X Arduino UNO r3 board

I attched the eagle file and the schematic circuit. You can download it.

Step 2: Plug Tiny Circuit to Arduino

After you built the circuit, you can plug it to your Arduino UNO board using the male header. (Pins GND,13,12,11)

Step 3: Upload the Sketch.

Now connect your Arduino UNO board to your computer and open the Arduino IDE.

Then download the sketch file i attached and open the .ino file using the Arduino IDE and upload it to your Arduino board. After the uploading process complete open the serial monitor in your Arduino IDE. Now you can see the message like 'Please attach your transistor'.

Step 4: Plug the Transistor You Need to Check.

Now plug the transistor you need to check to the female headers in the circuit.

Step 5: Getting Result

After you plug the transistor to your circuit, the Arduino board pass the transistor information to the serial monitor. You can read the transistor information in serial monitor.




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