Compact LED Tester

Introduction: Compact LED Tester

The goal of this instructable is to create a device that will test if LEDs work. Placing the LED legs into the female pin headers and pressing the button will determine if the led works. Before you begin with this project, you should have a basic understanding of 3D printing and soldering. If you're unable to do these things, I'd recommend saving this project for later. Without further ado, you'll need these components and tools:


  • A 9 volt battery
  • A 110 ohm resistor
  • 4x Female pin headers
  • A 6.9mm button, available here.
  • A 9 volt connector available here.


  • Wire cutter
  • Wire stripper
  • Glue gun
  • Soldering iron
  • 3D printer

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Step 1: Printing the Body

Before starting the rest of this project, setup the 3D printer. The file is here, feel free to modify it to your liking, but keep the primary dimensions. Once you finish the printing job, you can move onto the next step.

Step 2: Gluing the Connector

Begin heating the hot glue gun.

The connected pack has two wires sticking out from the top. Pull both wires through the hole in the bottom of the button chamber (From now on, I'll be referring to the black wire as the negative and the red wire as positive). Push the container up against the bottom of the chamber and glue it down.

Step 3: Wiring the Button

Begin heating your soldering iron

Place the button into the front opening of the button chamber. Once in, tighten the nut until the button is secure. Connect the positive (red) wire to one of the button's pins. Solder the connection. Once soldered, continue to the next step.

Keep the soldering iron on

Step 4: Wiring Part II

Place all four the female pin headers into the holes in the topper. Once they are sticking out of the top, grab both of the wires on the positive side (circled in white above) and connect them both to resistor. Solder the connection. Once they are connected, then solder the other end of resistor to the available pin on the button. You're almost done with wiring, continue to the next step.

Keep the soldering iron on

Step 5: Wiring Part III:

Grab the remaining wires on the lid's negative side. Connect them to the negative (black) wire from the battery. Solder this connection. Once you're done with this, continue to the next step.

Step 6: Finishing Up

Now that you're done with the wiring, test it to see if it works. Place an led into the header and press the button. Hopefully it works. If not, check your connections and consider resoldering. If it works correctly, you're nearly done. The last step is to glue the lid and button chamber together. Heat up your glue gun. Lay a ring of glue around the upper edge of the button chamber place the lid into the button chamber. Congratulations, you're now finished. Attach the connector to a battery and fit it into the battery chamber. Snap it all together and test out an LED. If it all works together, you're done.

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    3 Discussions


    3 years ago

    hi i have got a question. it seems you connected the female pin header in parallel.

    but i dont understand why you use a 110 ohm resistor?

    i.e. if you use ONE 3v led 20mA with this 9v batterie you would need 300 ohm

    and if i put a second (same) led in i would need 150 ohm


    4 years ago

    Great looking tester!


    Reply 3 years ago

    Thanks mate!