I'm trying to power a nRF24L01+http://www.nordicsemi.com/kor/Products/2.4GHz-RF/nRF24L01P with a Arduino Mini http://www.arduino.cc/en/Main/ArduinoBoardMini. Unfortunately the mini doesn't have a 3v power supply, it has a 5v. I'm sure this is a noob question that could be fixed with oms law. But I have a hard time learning by looking at equations. Does this need to be done with a voltage regulator or by using resisters as a voltage divider?
A voltage divider would work fine for powering the radio. Voltage divider - Wikipedia
Keep in mind that the TX voltage will also need to be dropped. The RX voltage will be an issue, since the Arduino expects 3.0V+ for HIGH, and anything lower is LOW.
There are 5V versions of that radio.
The radio doesn't use the TX or RX pins, does that make a difference.
I'm soing some kind of same job with arduino nano and RF24 (the one with PA amplifier that needs 150ma when Tx).
I use for the moment a LM3940-33 regulator. This one needs 5v input to do his job. So from the scheme is like that :
9v -> 7805 -> lm3940 -> 3.3V
with few condensators.
Hope it can help you.