Best way to power Arduino sub modules?

Hy guys,
I’ve understood that it will be better to power my Arduino Mini Pro using an external DCDC converter instead of connect it directly to the battery of my motorbike.
Well… what about the sub modules I’d like to attach to the Mini? My gadget require:

  • BLE HM-10 Bluetooth module
  • Catalex micro SD card reader
  • RTC module to be able to get the correct date and time. Which small and simple module do you suggest to buy?

I think I have al least two possibility:

  • power my Arduino from an external 7809 DCDC and then attach all the three mopdules to the 5V or 3.3V pin of the Arduino
  • power all the modules and the Arduino from an external 7805 DCDC

Can you please help me? I’d like to do a smallest and simple gadget as possible without a rick to burn sumething considering also that I want to put all the HW in a very small plastic waterproof case.

Thanks!
Marco

Since your LM7805 outputs 5V, you can't use it to power your Arduino. You need between 7V-12V to power an Arduino safely.

I suggest you get two adjustable buck converters. One that's set to output 7V for the Arduino and one that's set to output 5V for your sensors/peripherals.

buck converter link

Power_Broker: Since your LM7805 outputs 5V, you can't use it to power your Arduino. You need between 7V-12V to power an Arduino safely.

I suggest you get two adjustable buck converters. One that's set to output 7V for the Arduino and one that's set to output 5V for your sensors/peripherals.

buck converter link

Regulated 5v can power an Arduino just fine on the 5v pin, bypassing the onboard regulator. How else do you imagine an Arduino to run via USB's 5v?

Anywho. Calculate what your current (in the electrical sense, not spacetime sense) needs are for all your gizmos. Look for a 5v regulator or adjustable buck converter that has a capable current rating. You may want to get several and see if they survive the voltage spikes. Run all of your devices from the regulator, there is zero reason to run it through the Arduino. But if the Arduino is getting fed in the 5v pin, the two situations are electrically identical and you can use another 5v pin for convenience if you want. Either way, it's easier to heatsink a discrete reg than the Arduino's onboard one.

Why not hack a car usb charger? Some are good for 2A, and they are cheap and all available at every gas station around here for $5 US

INTP: How else do you imagine an Arduino to run via USB's 5v?

I literally just told him in the post you quoted. What makes you think he's running off USB power on a motorcycle, lol?

I know you can power it on the 5V pin and bypass the on board regulator, but that's a risk OP will need to be willing to take.

Power_Broker: Since your LM7805 outputs 5V, you can't use it to power your Arduino.

Please explain how I misunderstood this comment.

INTP: Please explain how I misunderstood this comment.

I was naturally assuming OP was going to use the VIN pin for external power. Gosh, someone get this guy a coffee.

Still haven't answered my previous question.

Markino76: Well... what about the sub modules I'd like to attach to the Mini? My gadget require: - BLE HM-10 Bluetooth module - Catalex micro SD card reader

You can power Bluetooth & RTC module from mini itself but micro SD card readers use active high current like 200mA max.

  • RTC module to be able to get the correct date and time. Which small and simple module do you suggest to buy?

DS3231 RTC module would be a great choice for its precision.

I think I have al least two possibility: - power my Arduino from an external 7809 DCDC and then attach all the three mopdules to the 5V or 3.3V pin of the Arduino - power all the modules and the Arduino from an external 7805 DCDC

Second option is better.

Thanks guys for the reply!