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servo current meter

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(@dan27)
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Joined: 5 years ago
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Topic starter  

I am using PC9685 to run a number of servos controlling robot arms that have variable loads.  Sometimes they do not move as commanded and I think I am overloading my power supply.  I would like a current meter that measures a few amps to within 10 milliamps so I can diagnose my problem.


   
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codecage
(@codecage)
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Joined: 5 years ago
Posts: 1040
 

Have you taken a look at the power supply that Bill built a few months back?  Using it as the supply voltage for your PCA9685s might give you a better idea of the current you are drawing for your servos.

Here is the link to his YouTube video:  Bill's Simple Power Supply

And here is the link to the Amazon supplied buck converter with meter that I used:  UCTRONICS-Numerical-Stabilized-Converter-Adjustable

I am in the middle of putting this together right now, but I'm unable to find the chassis mounted jack for the plug that is on the only available power brick that I have at the moment.  Guess I'm going to have to spring for a power brick with a standard sized plug.  The plug on the one I have needs a jack that accepts a 7.4mm plug with something that resembles a plug in the center of the jack that will fit onto the male pin that is in the center of my power brick's plug.  The way this is assembled seems to be just backwards of normal plug/jack combinations.

SteveG


   
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Robo Pi
(@robo-pi)
Robotics Engineer
Joined: 5 years ago
Posts: 1669
 
Posted by: @dan27

I am using PC9685 to run a number of servos controlling robot arms that have variable loads.  Sometimes they do not move as commanded and I think I am overloading my power supply.  I would like a current meter that measures a few amps to within 10 milliamps so I can diagnose my problem.

You may find the MAX471 or MAX4070 current sensing chips useful.   The MAX471 has an internal sensing resistor, but the MAX4070 allows you to use your own external sensing resistor which gives you more flexibility in fine-tuning the exact parameters you want.

MAX471 Datasheet

MAX4070 Datasheet

Here's a YouTube Video that explains how to use it.

DroneBot Workshop Robotics Engineer
James


   
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(@dan27)
Iam
Joined: 5 years ago
Posts: 5
Topic starter  

Thanks for these solutions, the video and especially the rapid response. I have ordered some Max 471s 

 


   
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