Seer Frights — Three-Knock
Everything you need. Where to find it.
The flat brass kind. Looks like a tiny gold coin with two wires. About the size of a quarter. Electronics store or online. About $0.10 each.
Black electrical tape. Holds the wiring connections together. Any hardware store or dollar store.
Optional — gives a cleaner click than touching the wire by hand. The tiny clicky kind, about the size of a pencil eraser. Buy a bag of 100 for a couple bucks. You only need one.
Building Version 2? You still need the piezo disc from above, plus these parts. The ATtiny85 controls the knock pattern — three knocks, then 24 hours of silence. No soldering needed.
Tiny 8-pin microcontroller. Program it once, it remembers forever. Runs on a CR2032 coin battery. Same chip used in the Swamp Glow and Route 13 builds.
USB programmer board for the ATtiny85. Plug the chip in, upload code from Arduino IDE, done. Same programmer used in the Swamp Glow and Route 13 builds.
3V coin cell. Powers the ATtiny85 and piezo disc. Same battery used in the Swamp Glow and Route 13 builds.
Holds the coin battery. Built-in on/off switch. Red and black wires connect to the ATtiny85. Same holder used in the Swamp Glow and Route 13 builds.
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