Turn an old phone into a Guestbook that people can leave personalized messages. Great for weddings, birthdays, product launches and other special events!

Kit includes:

• Teensy 4.0
• Teensy 4.x Audio Shield
• 3.5mm TRRS Breakout Board
• A Micro SD card
• Pin headers, both pin and socket

You will need:

• A landline-style phone
• Soldering iron and solder for the pin headers
• Electrical tape, or terminal block for wire connections
• Wire cutters and strippers

Software:

• Audacity
• Arduino IDE
• TeensyDuino
• SOX

Original design by Playful Technology on Youtube. You can follow his build guide, with timestamped chapters, here:

Make your own wedding audio guestbook – a step-by-step guide!

**If you have technical issues, check this forum post from the official Teensy forums to davice.