Light up Lab!

Firefly PCB Project!

Bill of Materials


1- LED

1- 390 ohm resistor

1- 10mm battery holder

1- 3V 10mm coin cell battery

2- 7" lengths 24 awg silicon wire

1- copper clasp

2- copper crimp beads

1- Light up Lab! Firefly board


Details and Sources

1- 5mm Yellow LED,  160-1953-ND, $0.29, Datasheet: LITE ON


1- 390 ohm Resistor, CF18JT390R, $0.10, Datasheet: Stackpole


1- Battery Holder for 10mm coin cell, BHX1-1025-SM, $0.48, Datasheet: MemoryProtection Devices


1- 3V 10mm Lithium coin cell, P031-ND, $0.88, Datasheet: Panasonic


2- 7" lengths, 24 awg silicone wire, BU24A80-06, $0.97 / meter


1- clasp copper hook & eye sets, 629783, $0.27


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1- crimp end copper .9mm id plain, 687802, $0.16


Basic Board Design

Tools you need

  • soldering iron and solder
  • tweezers
  • wire strippers
  • pliers
  • helping hands

Step 1- Solder on the battery holder

We found the easier way was to clamp on the battery holder and solder from the top.

Step 2- Crimp and Solder Jewelry findings

The next step is to put together your clasp.  This will serve as a switch in your circuit design.  Snip the wire with your wire strippers approximately 2mm from the end.  

Place your crimp on the end of the wire and squeeze with pliers until it's flattened and firmly secured to the wire.

It is not required, but the LED with have more consistent power if the crimp and the clasp are also soldered together.  If you choose to leave it without solder, it will have more of a flickering effect.

Step 3- Solder the Necklace Wires to the Board

Lay the circuit flat. 

Add solder to the corresponding circular pad on the circuit board.

Attach the wire into the hot solder and hold until it solidifies.

The soldering video again!  Check out Instructables for more how to videos and projects!

Repeat for the other side.

Step 4- Attaching the LED

Place your LED in position.  The positive side of the LED has the longer prongs.  This should correspond to the markings on the back of the Firefly board.

Bend back the wires and trim excess.

Add solder to the ends to affix.

Step 5- Attaching the Resistor

It's important that the circuit has a resistor to keep too much electrical current from burning out the LED.  A resistor has no positive or negative side.  Its function is only to slow down the current.  To attach the resistor, follow the same steps:

Insert the wires of the resistor into position.

Bend back the wires and trim excess.

Add solder to the ends to affix.


Step 6- Put it on!

Your finished circuit will look like this.  Close the clasp and let there be light!