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Relationship between "Power" and "Control" pins on servo motors

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(@amitjo)
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Joined: 3 years ago
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Hi,

   Is there any relationship between Power and Control pins on servo motors in terms of voltage levels? For example if I use this ULTRA TORQUE QUARTER SCALE 60KGCM METAL GEAR SERVO MOTOR ( https://robu.in/product/ultra-torque-quarter-scale-60kgcm-metal-gear-servo-motor/), power it from 7.4 Volts directly, can I then drive it through PCA9685 module that is say connected to an Arduino and is being powered and operated at 5 Volts? I'm having trouble getting such details from the servo part information available online so though of checking with experts.

Note: I've mentioned about powering the servo directly and this is for the reason that not all servos that I want to control through a single PCA9685 module operate at the same voltage and so I want servos to be powered directly with their respective supplies (and connect all grounds together).

Thanks and regards,

Amit


   
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(@dronebot-workshop)
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Joined: 5 years ago
Posts: 1073
 

Yes, you should be able to power it directly from your 7.4-volt power supply (which I'm guessing might be a LiPo battery?).  As long as you keep the grounds tied together, it will work.

The PCA9685 is providing the PWM signals required to position the servo motor. The Power connection on the servos is essentially a direct connection to the Motor Power pins (the 2-pin terminal block on the PCA9685).  So you could substitute your 7.4-volt power source, as long as the negative lead was connected to the PCA9685 ground.

😎

Bill

"Never trust a computer you can’t throw out a window." — Steve Wozniak


   
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(@amitjo)
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Joined: 3 years ago
Posts: 6
Topic starter  

@dronebot-workshop

Thanks Bill. So essentially there is no requirement from Servo motor to keep the PWM signal voltage level within some range of motor supply voltage. Makes sense!


   
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(@dronebot-workshop)
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Joined: 5 years ago
Posts: 1073
 

@amitjo Correct - the PWM signal level will be at the logic level, which in your implementation is 5-volts.

Look at pretty well any video that I've done using servo motors with an Arduino. I usually use a separate power supply, as the Arduino's onboard voltage regulator hasn't got a huge current capability, plus I don't like putting motors on the same supply line as my microcontroller.  And I often use a 6-volt battery pack for the servo.  So the servo, in this case, gets the Arduino 5-volt logic but is powered by 6-volts.

Your implementation is essentially the same thing, with a different supply voltage level.

😎

Bill

"Never trust a computer you can’t throw out a window." — Steve Wozniak


   
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(@amitjo)
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@dronebot-workshop

Thanks Bill!

Regards, 

Amit.


   
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