I am a hardware novice and need some advice. My circuit needs both 5V and 3.3V. Most of the time the circuit will be powered by an 11-14V source but occasionally I will disconnect from this source and it will be powered by a 9V battery. First, what techniques should I be looking at to allow the circuit to run uninterrupted when disconnecting from the main source and switching to the 9V battery then back to the main power source? Would a barrel power jack that includes a switch work? That is, inserting the barrel with the main power source opens the switch disconnecting the 9V battery?
Second, I get confused looking at the wealth of available voltage regulators. I have successfully prototyped using an LM317 to get my 5V. It has an input-to-output voltage differential of 3-37V so that appears adequate for my 9-14V input. I am using an LM2937-3.3 to get 3.3V from the 5V. The 5V side of the circuit will require no more than 150mA and the 3.3V side no more than 100mA. Are these regulators good solutions? At these currents and input voltages will I need to consider heatsinks? Thanks for any ideas.
Second, I get confused looking at the wealth of available voltage regulators. I have successfully prototyped using an LM317 to get my 5V. It has an input-to-output voltage differential of 3-37V so that appears adequate for my 9-14V input. I am using an LM2937-3.3 to get 3.3V from the 5V. The 5V side of the circuit will require no more than 150mA and the 3.3V side no more than 100mA. Are these regulators good solutions? At these currents and input voltages will I need to consider heatsinks? Thanks for any ideas.