I have a sensor comprising an ATTiny85 MCU, HC -SR501 PIR module and 433MHz transmitter.
The sensor is powered by 3xAAA batteries.
My objective is to reduce size.
One option I am considering is powering the sensor from an A23 12V battery.
The PIR module and transmitter can both handle 12V supply.
The PIR module outputs 3V (need to double check).
The only issue would be supply to the MCU.
- What would be the simplest form of voltage step-down to supply just the MCU.
- Am I better off, from a battery life perspective, to supply only the MCU with 5V or to supply everything with 5V via something like this.
Alternatively, is a suitable 12V tolerant MCU available/practical?