Open Sauce Badge 2024

Open Sauce is a super cool convention that takes place in the bay area. It’s kind of like a giant science fair, tons of people all bring the cool stuff they’re working on and show it off. The con is put on by William Osman and is visited by a bunch of other science and engineering YouTubers. Spiritually, it seems to fill the hole that Bay Area Maker Faire left after they closed up shop.

It’s a seriously cool convention, one of my favorites. I highly recommend that you check it out and consider going next year. They often do deals on early bird tickets! Check it out here https://opensauce.com/

The Badge

I was lucky enough to help design the official admission badge for Open Sauce 2024. One of my friends worked on the badge for the previous year, and they put me in touch with William.

For the record, I did not create the art for the badge. My role was building a circuit for the badge, creating a PCB, and working with our official sponsor PCBWay to actually get the badges manufactured.

Best Laid Plans

Originally we had very grandiose ideas for what was going to go on the badge. I don’t want to get into the specifics in case this idea eventually comes to fruition, so I’ll keep it vague. We wanted something fully assembled, with a microcontroller and a battery, and wireless communication. This fell through for a number of reasons.

1. Parts are expensive. With some design changes I was able to cut the BOM cost in half, but we still could not find a sponsor in time to pay for parts and assembly.
2. Parts are heavy. Our shipping cost went through the roof, even if we just stuck it all on a boat.
3. Our ideas required physical infrastructure to be set up at the convention. This infrastructure involved WiFi, which was going to be very difficult to successfully mesh over a huge, mostly concrete building.
4. Someone needed to write software for the badge. Good software! I can do that, but not with the dwindling amount of time we had.

What We Made

We eventually realized that the design had to be incredibly simple, and unpopulated. If con goers wanted to, they could acquire parts and assemble the badges themselves. These parts had to be very easy to obtain, hopefully things that most tinkerers already had several of in their parts bin. Bonus points if the parts didn’t need to be exact for the circuit to work.

I decided to go with a very simple circuit that is often used in schools to teach basic circuit design and breadboarding. It’s called an Astable Multivibrator, and all it does is cause two LEDs to flash on and off. This fulfills all of our design constraints

• You don’t need to use any particular transistor. Most jellybean NPN transistors would do
• You didn’t need to use exact values for the resistors or capacitors. If the weren’t perfect, the LEDs just flashed at a slightly different speed.
• It is very simple to assemble and the design is common and well documented
• All the parts are absurdly common. I spoke with several con goers who were able to put them together with spare parts, and at least one booth started handing out kits on day two (Thank you Colorado PCB Assembly!)

What We Learned

People really liked putting together the badges themselves! So much so that I am hesistant to push for fully assembled badges. They should have at least some DIY component, like an SAO port.

I also did a really horrible job with the transistor footprint. The leads are waaaay too close together and everyone (including me) had a really hard time soldering this in without bridged connections.

We need way more time than we think to make a badge, especially working part time on it. I could probably do it in three or four (sleepless) months if I took a sabbatical from my day job, but a polished badge needs a full year of design work if I only work on it a couple hours a week.

Next Year?

I hope I am asked to help out with the badge next year! I already have some ideas and a couple of dev boards and parts purchased for prototyping stuff. I really want to push for something populated in 2025

Also, I made a custom badge for Technology Connections because I like their videos very much