Pet Firefly in a Bottle




The fireflies here in Wilson NC were drawn to a white LED flashlight I was waving around, so I decided to see if I could make a Pet Firefly for my Sweet Heart. I got a cheap white LED and some fake flowers for him to sit on.


Step 1: Parts & Getting Started

I like to take LEDs from cheap $1 store items. Leave the leads long. Take a needle nose plier and bend the leads 90 degrees as shown. then bend the end of the lead into a ring to grip the flower stem it sits on, you can solder a fine wire to each lead or just crimp a wire in the ring you made. Run the wires for power down the stem. I used a thermal clay to make the black body and red sparkle paint for his eyes. I used fine wire to shape the wings and UV cure plastic to fill in the clear wings. You don't want to heat the LED too much, so I used a heat gun to set the body. To give the firefly a more real look, I dipped the LED in my UV plastic and then in Polymer powder to frost it.

Step 2: Find a Jar for Your Pet

I put together four LR44 size batteries and a field effect transistor with a short wire on its gate, so that any movement around the bug will cause it to light. Glass jars would not hold a charge for me, so I used a plastic Peanut Butter jar. let the lead from the FET gate just hang there. On a very dry day you can just walk by the firefly and he will blink at you!

Step 3: Here's Winking at You Kid!

You can hide the batteries with fake grass, I just have my flowers sitting in the jar. You must get the polarity right for the LED to light, other than that it is quite simple.



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    9 Discussions


    10 years ago

    This is a great Instructable, but you need to add a main image of the final project to the intro step. Please do that and leave me a message when you have so that we can publish your work. Thanks!

    1 reply

    Reply 10 years ago on Introduction

    Hi randofo! I added a new picture to the intro, I had to touch up the eyes and wings so they would show up. I wish I had a better picture of the legs, but I would have to take more close-ups for this.


    9 years ago on Introduction

    Hi john_doe01, for my prototype I used the amplifier from a capacitor mic, but a junction FET should work. there are some that are normally on, but you would need the normal off kind to save on battery power. I leave the gate lead dangling to pick up any static voltage, as when you touch the jar or rub it. You need about 4.5 volts going through the source and drain to the white LED.  I could look through my parts & get a number. I found out that you can take a transistor from anywhere Google the part number and get a data sheet on it! A cheap cap mic from Radio Shack or better yet from an old phone seems to have a FET as its amplifier. My mic was from a hearing aid, very tiny!

    2 replies

    Reply 9 years ago on Introduction

    Ahh, i get where i was going wrong now,
    but the transisters ive used are still nowhere near sensative enough.

    Any more sugestions?

    And thanks for the reply, really helped


    Reply 8 years ago on Introduction

    Sorry for the late response, I just saw your post today, My firefly would work fine outside of the glass jar. Just walking by would light it, but in the jar it was too insulated from movement outside, so I tried a plastic peanut butter jar, rubbing the jar lights the fly. You might try a isolated gate FET but watch out for too much static. I played around with a power FET that would turn on a small motor if you moved your hand near the gate lead.


    Reply 8 years ago on Introduction

    Yes, here in Wilson NC I haven't seen any in 3 years or so. You may find some in the country here and there. My firefly is made from an LED and Sculpey clay. I think the city sprayed for skeeters and killed a lot of them. Once I was outside with a small LED light (white) and flashed it around and pulsed the light only to be attacked by one of the fireflies! He went straight for the light with his light blinking away.


    9 years ago on Introduction

    Hi, ive been looking over the net and canrt find how you wired up the transister to the LED.
    could you please put up a circuit diagram and also give the transisters part number.