Powering servos and arduino (2)

[caecilius]

Hello,

On an excellent (but now closed) old topic (Powering servos and arduino), I learned a safe way of using one unique power supply to both power my servos and my Arduino.
Basically, the idea is to use a regulated power supply, with enough current (power), and a decoupling filter:

However, still a couple of questions remain:
1-Where in Arduino Uno should I connect the 5V? In Vin? Or perhaps in 5V port? Other?...
2-Where in Arduino Uno should I connect Gnd? In a Gnd? Any Gnd? Other?...

Please clarify.
Thank you!

[UKHeliBob]

Connect the 5V in to a 5V pin an GND to a GND pin as you suggest

[caecilius]

Ok, I'll do that. Thanks.

Anyway, would that be the same if I connected the 5V to Arduino Vin?

[UKHeliBob]

No. The voltage supplied to Vin goes through a voltage regulator to convert it to 5V and this will not work if the input is 5V in the first place

[Wawa]

Powering an Uno, that draws about 50mA without anything else connected to it, through an RC filter with a 47ohm resistor doesn't seem right.
That could have a volt-drop across the resistor of 0.05A * 47ohm = 2.35volt,
leaving only 2.65volt for the Uno.
Maybe better to replace the resistor with a (1N5819) Schottky diode.
100uF is also a bit small for brown-out spikes (the Uno already has 47uF).
You could increase that to 470 or 1000uF.
Leo..

[caecilius]

I copied the original schematic from an old closed post. Which I assumed to be correct...

As you may already guessed by know, I'm a beginner... could you please post a basic schematic of what you are proposing? That would help me a lot!
Thanks.

[Wawa]

Same diagram, but replace the 47ohm resistor with a diode (cathode/ring on Arduino side).

If you use a Schottky diode, then you only loose ~0.4volt instead of the ~2volt with the resistor.
You could also use a normal diode, but then the loss is about 0.7volt (still ok for an Uno).
Leo..