Arduino with external power supply for Servomotor

Using Arduino Motors, Mechanics, Power and CNC
1

Hello everyone!!

I want to connect a Servomotor 5v-7,4v to Arduino UNO R3, with the signal cable to a PWM (-9) and the + and - cable to an external battery of 7,4v 2000mah. Arduino will be powered by another battery 9v to the jack if it is needed.
The Arduino GND to the protoboard connected with the GND of the Servomotor and the GND of the battery.
My question is the next one: Can I connect the Arduino GND to the external power supply (battery) if this has 7,4v 2000mah?

Below there is a prototype, can you check if it is correct?

Proto servo
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2

Your connections look okay.

7.5v to the servo needs to be checked.

4

If it is found that the breadboard does not have enough current capability for servos building a power distribution board works well. If not up for soldering use a power distribution block of some sort.

Servo stuff

Power externally.

power distribution blocks.

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5

Hey LarryD. The battery is 7,4v not 7,5v (I didn't find any similar prototype of battery for the photo...)

If I would like to connect two servos 5-7,4v with the battery, I need to increase the 2000mah of the battery to 4000mah (a bigger battery)?

6

Hello Idahowalker!! So if doesn't have enough current capability could be for the breadboard? With the D-1459 I could solve this problem?

7

Two toy servos will probably work with a 2A supply.

Suggest
4 X 1.5V (AA) = 6V, sufficient for toy servos.

image
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8

Yes I know that with 6v would be enough, but I want to take all the power of the servo... The stall current of it is at 7,4v 2400mah. For this my question, if I want to connect 2 servos, I need a bigger battery (4000mah for example) or 2000mah is enough?

9

What does this mean ?

If the servos will not start up at the same time, when one servo finishes its initial current draw the second servo can take its initial current draw.

What servo are you using ?

How will the servos be operated ?

10

I mean that I want to take the max. kg/cm of the servo. I'm using the DS32355G.
Both servos will work at the same time!

11

Let’s assume the stall current for each servo is 2A.

The rule is to have a power supply that can supply 4A (or more) for two such servos.

In practise 4A might be over kill, however, sounds like you may be pushing these servos to there upper limits.

For extended use and battery longevity, a 7.4V lithium type battery rated at 4, 6, 8, 10A etc., might be warranted.

BTW, a large capacitor can be placed across the servo power leads to supply instantaneous current requirements.

Edit

FYI

https://www.sparkfun.com/servos

12

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