I was not able to understand all of that, but you cannot control a servo’s speed by changing PWM duty cycle the way you would with a DC motor.
Have a look at the sweep example of the library.
1A PSU for servo which has 1A stall current is not ideal choice...
Servos work in such a way, that the pulse length defines the position of the servo. In neither way it controls the speed or the movement of a servo. To move your P16R ( linear actuator with servo control ) you must vary the pulse length slowly and the position of the actuator will follow the change of the pulse length. The speed depends of how fast you vary the pulse length with every cycle. The max and min pulse length defines how far the actuator will go back and forth. The controlling pulse is completely independent of your 12V motor suppy. It's only a control signal.
[EDIT] - duty-cycle ( in %) has (nearly) no meaning for a servo. The absolute length of pulse defines the position, not the repetition rate.
Thank you for the most meaningful and useful reply. I understand how to modify the code. The other reason to select the higher control signal frequency was to reduce jitter.
I don't understand that. What jitter are you talking about?
There are servos that can be controlled with a higher repetition rate of the pulses. These servos can change their position very fast, and in this case it may be not sufficent to send a position pulse only every 20ms. I don't think your actutator is that fast.
That is the recommended (by Actuonix) specification. The actuator is controlled by Actuonix Ext-R. The datasheet is at https://www.actuonix.com/assets/images/datasheets/Actuonix%20Ext%20-R%20Datasheet.pdf?srsltid=AfmBOoqFqvQV5XgwPBy-uZEbVRmwGikr_i5SKrsUx9jsdG0CAjGWw4Ru
In this, they specify 6-12V minimum 1A power supply.
Can you post a link to that specification? I couldn't find that.
I just posted a link to Ext-R datasheet. The P16R is connected to Arduino through Ext-R which provides necessary digital PWM interface. Here, you will also see control input is PWM with 1-2ms high time, 50-300Hz period, 5V amplitude. I have lost track of the reference to using higher frequency for smoothness of operation. As soon as I find it, I will post it.
So you pick the minimum...
And 250hz is likely giving you just more jitter.
I am not sure what you mean! I am going by my basic understanding and the Ext-R datasheet. I can use the current limiting potentiometer on Ext-R (which goes from 0 to 1A) to lower the current supplied to the actuator. If you are expecting me to pick an external power supply greater than 1A, how is that going to help? Yes, there are discrepancies in their documentation but I did talk with the technical support team before buying the actuator and required external components. Again, you guys are the experts. Your comment on 250Hz giving more jitter (or jerkiness as their tech support said) is hard for me to groke. My simple brain says higher frequencies will result in smoother outout.
Yes, always pick power supply that has amp rating higher than minimum.
Stall current at 12V is 1A, so that's the theoretic minimum to start the motor. 12V2A would be correct choice.
But the potentiometer won’t let it go above 1A! You can see that in the datasheet. I thought the stall current means he maximum current a motor draws when voltage is applied but the shaft is prevented from turning (blockage or overload). Please send me a link to study more about the stall current being the current required to start a motor. I have more than 40+ yrs experience in electronics design and software development but I am always eager to learn more. Unfortunately, I am very slow and have forgotten many things because of two stokes which destroyed memory and processing regions of my brain, otherwise, I would not be in this situation.
Actuator doesn't have potentiometer. If your power supply does and it's limited to 1A, just replace it with something slightly beefier. At least +30%.
It's not for just this case, keep it in mind with any electronics project.
The actuator does not but you are using with Ext-R. You can’t use it directly. Power and signals are applied through Ext-R. Please look at the datasheet.
I didn't notice your link to the datasheet. So you have control board with current control.
If you want to drive it at max current, your PSU still needs to have some headroom.
It is 1.2A actually. I know it is not that much.
You have way more years experience in electronics than I do and this topic is solved, so I wish you good luck and go to sleep.
Thank you much. You are very kind. I might have been good once upon a time, not anymore, thanks to the strokes. Please continue to help others who are brain-dead like me. I am doing this project to facilitate my son’s thesis work who is studying architecture and have ZERO experience with electronics or programming. Thanks again.
Ok, but this is really only a control input. It defines the position the actuator should run to. This does not directly control the motor in any way. That is the task of the EXT-R control board. Therefore, I do not understand how the control signal could cause a jerky operation ( as long as the position signal ( =pulse length) is stable and not jerky ).
Thanks for your input - what you said makes perfect sense. It is entirely possible I misheard or misconstrued what the tech support person told me. My apologies if that is the case.