Attiny85 is a small Microcontroller. You can use this microcontroller to do different tasks. you just need to code in the IC whatever you want to do with it. For this project, we are willing to make a Simple Breathing LED Circuit with timing delay control. So that we can control the Breathing Delay. For this, we are using a 100K potentiometer.
The LED is connected with the Digital Out of the Attiny85 Microcontroller IC. Here I have used a 220R Current Limiting resistor. the Attimy85 IC works on stable 5V. So, you will need stable 5V Output for running the circuit.