How to choose resistance?

Question

Arduino

I recently bought an arduino due, in principle there is a general understanding. BUT it is powered by 3.3V. power source.
I have two adapters one for 6v 300mA. Another for 5v 2A. Help me determine what resistance to put on these adapters.

Answer 1

The resistor will not work, since the current consumption of this board is dynamic! that is, it falls then it grows,
see for yourself we take 5V - 3.3V = 1.7V - then what should fall on the resistor
now we take the current from the description
50 - 800 mA
for a current of 50mA = 0.05A R = U / I = 1.7 / 0.05 = 34 ohms
for a current of 800mA = 0.8A = U / I = 1.7 / 0.8 = 2.125 ohms
you need a linear or pulsed DC-DC converter.
Or read the technical documentation for your product.
where it is written in black and white that it can be powered from 5 volts.
There are ready-made modules such, it costs up to 250 rubles
. Or you can assemble it yourself, but you have to tinker. LM1117-3.3, Linear stabilizer
it’s not difficult to calculate 100 microfarads per 1W of consumption to find out the power consumed by your arduino, look at the datasheet, but I think no more than 1 ampere * 3.3V = 3.3 Watt so 470 microfarads (microfarads) 30V is enough. At the output, film to smooth out interference from the regulator, there, according to the dataset, set 1-10nF (nanoFarad) if
something is not clear, ask in the comments, I will explain, but the resistor will not help, I will comment later why
or plug into a breadboard. A selection from the chip dip store, choose what suits and ...
here is the circuit that you need to assemble
or buy a ready-made module for power supply.

Answer 2

If you need 3.3V, then stabilizers or Step-down modules are better.
The resistor is bad because when the load changes, the voltage will float, but you need a stabilized one.
I just looked at the site about Due:
arduino.ru/Hardware/ArduinoDue

Operating voltage 3.3V
Input voltage (recommended) 7-12V
Input voltage (limit) 6-20V

And 3.3V is the logic voltage.
An external power supply of 7-12V is recommended.
To interface with 5V logic, you will need to sculpt intermediate modules, because you should not send more than 3.3V to the pins.