I posted an earlier question on digital pins in which I was informed that I was erroneously using a level shifter to accomplish a drop in voltage from the 5v digital output pins on an Arduino Uno to 3v to drive 3v LED's. Instead I should have used current limiting resistors for that purpose.
So, I am now wondering what is the proper use of level shifters? When can/should they be used instead of adding resistance to accomplish voltage drops?
In particular, one aspect of the motion sensing system I was trying to create relies on those inexpensive 433MHz RF chips all over EBay to perform the communication between the motion sensor and the base unit. I deployed one of the motion sensors, which I confirmed was functional in close proximity to the base unit, outside and I do not get a signal on the base unit when motion occurs in front of the sensor.
In the sensor unit, I am using a 9v battery to power a Arduino Nano via the Vin pin and using two 5v pins of the Nano to power both the sensor and the RF chip. In Google searches I found that if I were to increase the voltage on the RF chip (it can handle up to 12v) I would get greater range. So, could a level shifter be used to enable me to power the RF chip directly from the 9v or 12v source but trigger communications from a 5v digital pin on the Nano or should I use a transistor to convert the 5v signal to a 9v/12v one for transmission?