There are 1 repository under attiny13a topic.
Uninterruptible Power Supply
I²C OLED on an ATtiny10/13/202
T12 Quick Heating Soldering Station
IR Remote Control
OSC Calibrator and High-Voltage Fuse Resetter for 8-Pin ATtinys
ATtiny13 Software UART library.
12-Button IR Remote Control
FM Stereo Radio with Headphone Plug
Simple Logic Probe
IR Remote Receiver and Decoder
Collection of AVR Development Boards
RF Remote Control
Automatic Volume Adjuster for TVs and Sound Systems
Simple Continuity Tester
Dimmable USB Night Light with Capacitive Touch Control
Magnetic Door and Window sensor sends open and close code to home automation system
Control almost any number of NeoPixels with an IR Remote
Soil Moisture Monitor
It just does bling bling ...
Lightweight WS2812B RGB led driver for the attiny13
Night Light with NeoPixels and Rotary Encoder
Simple Candle Simulation
IR Remote Controlled MP3 Player
Tiny Electronic Dice
ATtiny programmer board for use ArduinoUNO as ISP
A Morse code to logic-level serial converter for ATtiny13A/25/45/85
Use a small microcontroller (e.g. ATtiny13) to respond to a momentary switch and drive a relay and status LED
Solar Powered Blinken Lights
Ultrasonic Range Finder
This is scrolling LED banner based on customizable set of MAX7219 modules and ATTINY85 / ATMEGA328 chip. Supports up to 32 daisy chained 8x8 LED matrix modules and scrolled texts longer than 5000 characters. When using ATMEGA328P you can send text message to display via serial port and FTDI232 adapter
GPS clock on an ATTiny with MAX7219 7-segment driver