Automatic Glowing Mushroom Nightlight

Bioluminescent mushrooms are amazing! I've always thought they were so cool and wanted to have my own little terrarium with them. This is a tribute to those fascinating fungi. The mushroom in this project will automatically glow brighter the darker it gets.

• Plastic cloche (plastic dome)
• Artificial moss rocks
• Foam flock (green)
• Mini mushroom cap (mine was recycled from another project)
• 3D printer and filament
• Mini PCB board or perfboard
• Soldering iron and solder
• Heat shrink tubing 3/16" (white) and heat gun
• Solid wire and wire cutters
• Coin cell battery (CR2032)
• LED (any color. I used blue)
• LDR (photoresistor)
• 100kΩ resistor
• NPN transistor (2N3904)

I always like to test my circuit on a breadboard before soldering. You might want to change the 100kΩ resistor to more or less depending on your lighting situation. Once you're sure it works, solder the NPN, LDR, and resistor to your board, following the schematic. I used a PCB because that's what I had on hand, but a perfboard would save you more room.

When soldering the LED, increase its height from the board by attaching it to a pair of wires. Slide it into the heat shrink tubing, leaving the LED poking out of the top. Apply heat from the heat gun. This is the stem of the mushroom. Add the mushroom cap on top of the LED.

Solder two wires for the battery connection.

I used Tinkercad to model a custom case and cover to fit my board. It's great because they have built-in models of different electronic components. With these, I could see how much room I needed for things such as the battery.

When modeling, create a case that has an opening for your battery to slide in. I put my battery under the board. The cover should have two holes. One to allow the LED to poke through and the other for the photoresistor to detect light. 3D print your case with desired filament.

Using the foam flock, cover the top and sides of the case, leaving the photoresistor visible.

Place the case in the cloche and add moss rocks. Don't cover the photoresistor or it won't be able to detect light.

Your mushroom light is complete! In the dark, you'll see it glow brighter as the resistance decreases.