how we can connect 8 servo motor ( MG995 MODEL ) to arduino

hi guys

how we can connect 8 servo motor ( MG995 MODEL ) to arduino ?? we need driver to run it ? or directly connect them to arduino ?

Connect control signal to Arduino. Connect seperate power source & Gnd to servo, with power source Gnd connected to Arduino as well. Use Servo.h library.

CrossRoads:
Connect control signal to Arduino. Connect seperate power source & Gnd to servo, with power source Gnd connected to Arduino as well. Use Servo.h library.

thank u for your attention , you say that for connect 8 servo motor ( MG995 MODEL ) to arduino we dont need any driver ??

Operating current for each of MG995 servo motor : 100mA
that we have eight sevo motor

Did you understand that you need a separate power supply for the servos ? Only the signal wires connect to the Arduino. The power connections to the servos must be from a separate power supply.

And BTW I don't know where you got the "100mA" from but an MG995 servo can draw a lot more than that depending on the load on it so for 8 of them I'd make it a supply that can deliver at least 10A, maybe more.

Steve

slipstick:
Did you understand that you need a separate power supply for the servos ? Only the signal wires connect to the Arduino. The power connections to the servos must be from a separate power supply.

And BTW I don't know where you got the "100mA" from but an MG995 servo can draw a lot more than that depending on the load on it so for 8 of them I'd make it a supply that can deliver at least 10A, maybe more.

Steve

So thanks , I got it !

"for connect 8 servo motor ( MG995 MODEL ) to arduino we dont need any driver ?? "

Yes, only the control signal that the Servo.h library creates, and power from a separate supply.

CrossRoads:
"for connect 8 servo motor ( MG995 MODEL ) to arduino we dont need any driver ?? "

Yes, only the control signal that the Servo.h library creates, and power from a separate supply.

thank u , but with just one servo motor MG995 , we dont need separate power supply, its true ?

one other question , this that from where we can know Operating current of motor ? in data sheet didnt have any information

• Weight: 55 g
• Dimension: 40.7 x 19.7 x 42.9 mm approx.
• Stall torque: 8.5 kgf·cm (4.8 V ), 10 kgf·cm (6 V)
• Operating speed: 0.2 s/60º (4.8 V), 0.16 s/60º (6 V)
• Operating voltage: 4.8 V a 7.2 V
• Dead band width: 5 μs
• Stable and shock proof double ball bearing design
• Temperature range: 0 ºC – 55 ºC

and how much AMP , arduino mega or uno , can provide for run a motor ?

Hobby servos are notorious for never stating the current they require because it depends so much on how much load is placed on the servo. You can only either guess or measure it yourself.

It is always a bad idea to power servos or motors from the Arduino. Always connect them to a separate power supply. Anyway it is impossible to know how much power you could take from the Arduino without knowing what power you are supplying to it. Is it powered from the USB lead ? Or batteries ? What sort of batteries, what size and how many ? Or a power supply ? And so on.

Steve

slipstick:
Hobby servos are notorious for never stating the current they require because it depends so much on how much load is placed on the servo. You can only either guess or measure it yourself.

It is always a bad idea to power servos or motors from the Arduino. Always connect them to a separate power supply. Anyway it is impossible to know how much power you could take from the Arduino without knowing what power you are supplying to it. Is it powered from the USB lead ? Or batteries ? What sort of batteries, what size and how many ? Or a power supply ? And so on.

Steve

ow , that was so good explanation

BEST REGARD , Steve

rezarei89:
in data sheet didnt have any information

It doesn't list the current, but all the info you need to calculate it is there.

nyphot:
It doesn’t list the current, but all the info you need to calculate it is there.

O.k. I’m game to learn something new. How do I calculate the maximum current the servo will draw from that specification ?

Steve

slipstick:
How do I calculate the maximum current the servo will draw from that specification ?

rezarei89:
• Stall torque: 8.5 kgf·cm (4.8 V ), 10 kgf·cm (6 V)
• Operating speed: 0.2 s/60º (4.8 V), 0.16 s/60º (6 V)

P=Tw and P=VI so I=Tw/V:

T=10kgf.cm ~ 1Nm
w=0.16s/60º=0.15s/rad=6.5rad/sec (1rad=57º)

so I = 1x6.5/6 = 1.1A @ 6V assuming all the electrical energy is converted to mechanical efficiently.

In practice you'd be lucky if a servo was better than 50% efficient due to the small size motor
and stack of mechanical gears.

Yes, that's the bit that's missing from the specification. Servo efficiency is nowhere near 100% and, from experience, is very variable even from one example to another of "identical" servos.

But it is still useful even if you have really only calculated the OUTPUT power and so the very least that you can expect the stall current to be. But I had forgotten that mechanical P=T.w stuff...I'm definitely getting old.

Steve

Adafruit has a 16 channel addressable servo board.