ruddblink

ATtiny85-based illuminated PCB keychain featuring the Ruddock House crest

Description

Ruddock House is one of the eight student houses in the undergraduate housing system at Caltech and was founded in 1960. Some notable alumni from Ruddock House include Peter Shor, Bill Gross, Eric Betzig, and Michael Rosbash. The current house motto is Virtutis mammilas exsugimus.

This is a 1.6" by 1.9" PCB keychain featuring the Ruddock House crest on the top copper, based on the original Ruddock crest PCB keychain. A ring of 8 LEDs around the crest is controlled by an ATtiny85 through a 74HC595 shift register. This keychain is intended to be compact and aesthetic, but also simple to solder; all packages are SOIC and 0805 or larger.

The keychain can be powered by a single CR2032 coin cell through the coin cell holder footprint on the back, or through an alternative power source soldered to those pads.

Features

• ATtiny85 in SOIC-8 package driving 74HC595 shift register in SOIC-16 package
• PWM-able output
• Power switch
• User pushbutton
• MOSFET polarity protection
• PTC fuse
• Aesthetics

Notes

No input voltage regulation is present. Do not apply more than 5.5 V, the maximum voltage for the ATtiny.

This PCB is designed with KiCad EDA 5.1.4. Schematic and board files may be found under /ruddblink, with documentation under /ruddblink/doc.

Author

• Ray Sun - Undergraduate, Electrical Engineering, Caltech, Class of 2020

License

Unless otherwise noted, this schematic and PCB design, with associated symbol and footprint files, are licensed under a Creative Commons Attribution-ShareAlike 4.0 International License. The Ruddock House crest is copyright of Ruddock House and used with permission.