What power regulator can I use ?

[FvM]

Transmitter current and duty cycle are the parameters determining the minimal required battery capacity. If you can't go below 135 mA and the 200 ms every 8 s duty cycle, the total 32 Ah/a calculated by CatM in post #6 applies. If your battery voltage is higher than 4V, using a high efficient switching regulator pays. But you can't go below e.g. 9-10Ah/a with a 12V battery. Means you either need to provide a large battery or overthink the intended packet rate and duty cycle.

 

[Easyrider83]

Where did you get 200ms? Open please datasheet and calculate tx time. It will be 500 time less.

 

[FvM]

I neither know where pic.programmer got the 200 ms, I'm just quoting the numbers... Unfortunately he didn't yet correct it.

Designing an appropriate transmission scheme is the essential point, much more important than using this or that voltage regulator.

 

[pic.programmer]

I assumed it. I didn't check the datasheet.

Current is mentioned here. It is 115 mA during Tx. See specification table.

**broken link removed**

Also in the Caution section of the above link it is mentioned that signal lines of NRF can be directly connected to 5V MCU. So, shall I powernRF directly from 3.3V CR2032 and use 3 V to 5V DC-DC Booster and power ATMega from booster and Ultrasonic sensor from ATMega328P ?