power supply

hello, i'm new on arduino dev.

i'm creating project read rfid , send bluetooth.
all worked fine times. bluetooth module can't communicate. if disconnect rfid module, bluetooth works fine.

i think power insufficient or rfid module spend many power.

so need alternative power supply or no? how use it? both modules spend 3.3v, using 9v battery, best regulator?

thanks

don't start 9v battery - have poor current handling, , you're regulating them down 3.3 (throwing away 2/3rds of power!).

3.3v through hole ldo regulators - can used pack of 3 aa batteries - last many times longer 9v battery, , can take current:
digikey catalog link

or use dc-dc converter generate 3.3v if must power higher voltage, , need efficient:

ebay search results

or use 3.3v wallwart if it's not portable application (or higher voltage wallwart feeding ldo or dc-dc converter).

when using multiple power supplies, connect grounds.

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