The Tram Badge to rickroll 400+ people

Story

The Design

I happen to randomly come across Böset on Twitter who is one of the founders of the popular Gothenburg-based IT security conference called Security Fest. And after a quick chat, it wasn't long before we started brainstorming about what badges we can make for Security Fest.

Gothenburg is famous for its legendary trams and that's exactly what we wanted on the badge. A classic design with rustic elements to it. Because the time was super short, we decided to stick to something that has favorable development energy involved.

So for the circuits involved - we wanted to glow the headlights in darkness and do something cool with the tram horn.

Some design elements were an obvious choice - window cutouts on PCB, a large yellow LED for the headlight, and a glowing nameplate on the top with reverse mount LEDs. With that approach, the rest of the components fell into place intuitively. We put some white space at the bottom to allow attendees to write their names with a marker.

And it came in 3 colors - Blue for the attendees, Green for the speakers, and Black for the crew.

The Working

The badge comes partially pre-soldered with the two nameplate LEDs on the top side that glows Security Fest.

Glow In The Dark circuit is based on a light-dependent resistor or photoresistor coupled with a transistor that allows the current to flow through if there's no light incident on the sensor. In the rest of the cases of light incident on it, it stops the headlight from glowing.

The speaker idea was an experiment done for the first time ever which came with its own memory IC that stored the audio file and played it on loop.

In the hardware village we hosted, attendees were free to solder the Glow in the dark circuit and the speaker while being unaware of the surprise that was coming their way when they would turn on the switch.

The Tram Badge soldering tutorial is here.