Getting the correct servo specs with Arduino

Other Hardware Motors, Mechanics, Power and CNC
1

Hi

I am trying to understand the specs of servo required to connect to an Arduino Uno board.
The board pin max current is 40mA. My questions are:

  1. If i have a servo of 3v, 300mA; if i were to connect this servo to Arduino 3.3v and gnd with signal to Pin 10 of Arduino, does this mean the servo will try to pull 300mA from Pin 10 and fry up the board?

  2. My second question is related to question 1. Does this mean that i will need an external power supply of 3v with minimum 300mA to connect to my servo with gnd connected to Arduino's gnd?

  3. Pertaining to above, if i use the external power supply, how much current will it draw from pin 10 then?

2

pfnusg:
Hi

I am trying to understand the specs of servo required to connect to an Arduino Uno board.
The board pin max current is 40mA. My questions are:

  1. If i have a servo of 3v, 300mA; if i were to connect this servo to Arduino 3.3v and gnd with signal to Pin 10 of Arduino, does this mean the servo will try to pull 300mA from Pin 10 and fry up the board?

  2. My second question is related to question 1. Does this mean that i will need an external power supply of 3v with minimum 300mA to connect to my servo with gnd connected to Arduino's gnd?

  3. Pertaining to above, if i use the external power supply, how much current will it draw from pin 10 then?

  1. No, it will pull the current from the power pin, which also won't work because arduino boards only can supply 50mA.
  2. Yes
  3. Not very much. The current draw on servos happens on the power pin.
3

Why 3V? Standard servos are 6V and much more plentiful. In general
expect a servo to pull 1A or more peak and don't share power with logic.

4

Thanks for answer.

Yeah, I saw some tutorial online using low power 5v servo connecting signal, power and gnd with output logic pins. Since max output ams for logic pin is 40mA, i do not think any servo which works with current lower than 40mA?

5

Absolute MAX is 40mA - that should not be used as normal operating state.
Normal is 20mA, and you can expect voltage to drop to 4.2V and lower as the current increases.

6

pfnusg:
Thanks for answer.

Yeah, I saw some tutorial online using low power 5v servo connecting signal, power and gnd with output logic pins. Since max output ams for logic pin is 40mA, i do not think any servo which works with current lower than 40mA?

Power is power, signal is signal. You are confusing the two.