Basic sketch for an Attiny85 circuit with SG90 servo and TSOP4838 IR Receiver used to turn on a light switch, like a Switchbot

• Uses ATTinycore (https://github.com/SpenceKonde/ATTinyCore) and its built-in Attiny_servo library
• Uses IRMP (https://github.com/ukw100/IRMP) for Pin-change Interrupt-based IR receiving.

Notes

• Attiny85 powered by 2xAA 1.5V batteries
• Servo powered by 4xAA 1.5V batteries
• Uses IRLZ44N low-side Mosfet to switch on servo power
• Attiny85 sleeps (Power Down) after 3 secs of inactivity, and also switches off Mosfet gate; woken on Pin Change Interrupt (IR signal) and powers on Mosfet gate for Servo
• In my limited tests with DMM on perfboard, getting this current draw:
  • Attiny85 circuit: ~4.4 mA (Awake) and 217uA (asleep)
  • Servo: ~5mA (Idle) and 95uA (Mosfet off)