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Topic: Slow the speed of a continuous rotation micro servo  (Read 6995 times) previous topic - next topic

vinceherman

Keep in mind - ALL of these were designed as conventional servos.
The analog versions use control boards with design specific to conventional servo behavior.
The digital versions use control boards with design specific to conventional servo behavior.
The digital versions have a design that function better for conventional servo use.

For many years, robot enthusiasts have been modifying conventional servos into continuous rotation versions.
This gives a device that has good direction control and varying levels of speed control.
It turns out that in the examples we have seen on this thread, modifying a digital servo to be a continuous rotation device results in poor speed control.
Is that the case for all modified digital servos?
Is that the case for all modified analog servos?
In both cases, I think you end up with questionable speed control.
You are using a device that was not designed to provide speed control in a continuous rotation fashion.

So, the modified digital servos are not a good fit for your application.  That does hurt.
Consider buying more copies of the analog ones that looked to be a better fit.
Consider buying motor controllers and using their purpose built speed control capabilities.




usenetfan

That's it in a nutshell. This is what the Servo Shop UK says on its website after I pointed this out to them:


"MG90D Robot servo 360° Rotation

New Digital 13g Metal gear, double ball bearing servo.

Excellent for Robotic, clockwise/counterclockwise rotation,alloy casing in the middle.

Please note that this servo does not feature variable speed, only constant speed in CW/CCW rotation directions."

That will help future buyers.

Johan_Ha

Today I got my continuous servos from China. They're supposed to be digital, but I doubt it. They behave exactly like the continuous servos I've had before. And they behave good. These are nice for simple DC motor like robotics. Power them. Provide them with one data line. And you have a geared motor (low rpm), the speed and direction of which you can control with the single data line. For a real DC motor you'd need two data lines and an H-bridge motor driver. On my servo I read DM-S0090D Docman Hobby.

Here's a video.
Thats by the way a nice 4duino Uno Pro with a built in motor driver. In the upper left corner you see four screw terminals for two DC motors and two terminals for power input, like 12 V 1.5 A, which is what the board can output for the DC motors.
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