Being real, ultimate geeks, [Bill] and [Mara] didn’t want to settle for plain, paper-based wedding invitations. No, they wanted something cooler, and came up with their own DIY electronic wedding invitations.
Since they would be making the invitations themselves, [Bill] and [Mara] needed a simple circuit that could be easily mass produced. They turned to the classic microcontroller-powered blinking LED circuit powered by an ATtiny13.
The first order of business was producing 50 printed circuit boards for each of the invitations. For this, [Bill] picked up an Xerox Phaser laser printer off of ebay and a few sheets of copper-clad kapton film. The etch resist was printed directly onto the kapton film and etched in a bath of ferric chloride, effectively making a flexible PCB.
These circuit boards were soldered up and laminated between the printed invitation and the card stock cutter with the help of a Silhouette Cameo paper cutter. After the cards were assembled, the battery was wired up and the cards shipped out.
The microcontroller inside the card was programmed to be asleep most of the time, waking up only every few seconds to check a light sensor to determine if the card was opened or not. If the microcontroller sensed the card was open, the lights began blinking, making it one of the most memorable wedding invitations [Bill] and [Mara]’s guests will ever receive.
You can check out a demo of the invitations after the break.