Learning about the kit biz, preparing to launch Kickstarter campaign for ‘Jar of Fireflies’ kits

Posted on February 27, 2012 in Hardware

Some time ago, I created a very small set of jars outfitted with LEDs to mimic the behavior of fireflies, as part of my Artist in Residence show back in October. Since the show, I have been tossing around the idea of turning the project into a kit of some sort, and have been making some good progress to that end. Due to its low parts count, relative simplicity and positive feedback I’ve received about the end result, this project seemed like an ideal way for me to explore the possibility of selling kits for profit.

Schematic and PCB layout

Before anything else can really be set in stone, I felt it would be important to complete the schematic and PCB layout as soon as possible. This gives me an idea of the parts and space requirements for the kit, which will inform the later development stages. I decided to add a simple piezo sensor to the schematic, so that users will be able to tap their jars and alter the blinking patterns of the fireflies. Next, I decided on using a circular PCB design, with a diameter of 1.7″, to keep PCB manufacturing costs as low as I can (any larger and there is a price break at the board house I plan to use). The board will be mounted on the underside of the lid of a mason jar, attached using standoffs.


Not shown in the schematic or board layout is a 2zAA battery holder and an SPDT slide switch, which will be mounted on the topside of the lid of the mason jar.

Firmware updates

Once I have ordered the parts to construct a couple prototypes, I will begin hashing out some changes to the firmware I created for the original projects. The addition of the piezo sensor will present some interesting firmware challenges, which I hope to overcome by re-writing the whole thing. For one thing, the LEDs require 5 pins of the microcontroller to be driven correctly, which is leaves three pins on the 8-pin DIP package ATTiny85. Two of these pins are used for power, while the third pin is used as a RESET. If I’m lucky, I can use this RESET pin as an IO pin, but I may have to sacrifice programming functionality. We’ll just have to see how it works out.

Updated wiki article + Github repo

I’ve been updating my wiki with more up-to-date information about this project, to include better BOMs, Kickstarter pricing structure, shipping and packaging pricing and more. I hope to document the entire process of turning this project into a successful kit both on this blog and in the wiki, so keep an eye out!

View the Jar of Fireflies wiki article

I will also be maintaining a Github repo for this project, which will eventually contain the design files, the firmware, an assembly guide and more. For now, its a little empty, but will grow over the next couple months.

Interesting challenges

When I began thinking about turning this project into a kit, I was thinking primarily about the fun stuff; the PCB, the manufacturing, the documentation etc. However, being successful in the kit biz involves learning about a great deal more, such as how to actually ship a package from point A to point B. You need to choose the right-sized boxes, and account for all materials you might need, including tape and packing material (otherwise, you pay for it out of pocket, at a net loss). I think I have those things mostly figured out, but I still need to find out exactly how much it’ll cost to ship each package, which requires getting access to a scale and actually creating a complete kit just for weighing. Also, I need to figure out how to actually physically send 100 packages in the mail – I don’t exactly want to do wait in line at the post office and send 5 packages at a time! I hear there may be a way to arrange for the packages to be picked up at my home, but we’ll figure that out later.

Right now, I am planning to launch the Kickstarter campaign early this summer, around the beginning of May. However, if things really work out well and I feel comfortable, I may launch it earlier! Just keep watching!