Are you like me? Do you have a whole box of electronic components and no idea what the values are? It is time to sort out that box! But how? 

Reading the markings of the components individually or measuring each component with your trusty DVM? This might be fine for resistors but what about the rest of your components? And what about the damaged components that found their way into the box?

There is a very simple solution: build yourself a simple component tester with an Arduino UNO and a few easy-to-find components.

What you need:

Circuit diagram:

I omitted the battery and power LED and use an USB cable as power supply instead.


Original code by Karl-Heinz Kubbeler


My tester, working, but in desperate need of a nice 3D printed housing. The display text can be changed in the map to anything you like.

Here are some images of the different messages you get while the tester is doing its thing.

During the test cycle:

Testing a BJ 102 Triac:

Testing a NPN transistor:

Testing a resistor:

Testing a LED:

Testing a diode:

Testing a capacitor:

Note: take care to discharge capacitors before testing!!

This is how I built my tester with a small PCB board:

The board is very crude but it works just fine. 🤩 I had to bend the header pins to fit into the Arduino UNO headers. Using an UNO Prototype PCB Board would have made for a much neater build!

Original code by Karl-Heinz Kubbeler

For additional information:

Werner Muller

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