power supply

Hello, i’m new on arduino dev.

I’m creating a project to read RFId and send to bluetooth.
All worked fine some times. Usually the bluetooth module can’t communicate. If disconnect the RFId module, the bluetooth works fine.

I think the power is insufficient or the RFId module spend many power.

So I need an alternative power supply or no? How use it? both modules spend 3.3v, using a 9v battery, what is the best regulator?


Don't start with a 9v battery - they have very poor current handling, and you're regulating them down to 3.3 (throwing away almost 2/3rds of the power!).

3.3v through hole LDO regulators - can be used with a pack of 3 AA batteries - which will last many times longer than the 9v battery, and can actually take the current: Digikey catalog link

Or you could use a dc-dc converter to generate 3.3v if you must power it with a higher voltage, and need it to be efficient:

Ebay search results

Or use a 3.3v wallwart if it's not a portable application (or a higher voltage wallwart feeding an LDO or DC-DC converter).

When using multiple power supplies, connect the grounds.

I find plenty of 5V regulated switchmode “wall warts” (Phone chargers) at Garage Sales for $1 or so (frequently 50 cents) - or you can check out “Op-Shops”. Most recent ones are 1000 mA or even 2000 mA.

Thanks, the power supply is my suspicion. you think the problem might be it?