I have a M200 with Basic ESC and Thruster Commander. I’m gearing it down through a couple of spur gears which then turn an ACME threaded rod which moves a linear slider. If I reach the end of the threaded rod and the whole system becomes unable to turn what happens? Is there an overload in the ESC that will turn it off until the potentiometer is returned to the center? Is it damaging anything if I let this happen?
Hi @Dan1500 -
Welcome to the forums!
I wouldn’t expect any damage to occur, but the ESC may be at risk if the motor was spinning very fast and abruptly came to a halt?
The standard ESC runs by listening to the back-emf of the motor to determine RPM, and thus time the pulses of electricity that keep things rotating. Thats why at low RPM, things don’t really work - the ESC has a start sequence it will try to do, but if no back EMF is heard it can’t get things spinning.
In your application, if you can get the motor started, overcoming friction in your drive train, it will spin until the endstop is reached, and then stop. Reversing direction may require sending 1500uS servo pulse to re-initialize the ESC again?
I’d say give it a try, and see how the ESC takes it!
Thanks Tony, that leads to another question it can currently spin faster than we need to, maybe using only the first 20% of the potentiometer each way. Is there an easy way to limit the speed. Say instead of a potentiomer that gives you 1100 to 1900 microseconds is there one that would give you say 1400 to 1600 or something like that?
Hi @Dan1500 -
I would recommend swapping out your Thruster Commander for an Arduino, and adapting the range you’d like to control over in the firmware! We’ve got a guide and a quick chat with an LLM AI would get the code working, and even detail how to wire the potentiometer to the Arduino!
The way the potentiometer is used for the thruster commander is as a voltage divider, which distributes the available voltage between the two sides (using resistance). Any other potentiometer would do the same (possibly with more or less current usage), but you can adjust the sweeping range by adding fixed offsets (via static resistors).
In the case of the 10kΩ included potentiometer, adjusting down to a quarter of the variable range would require adding ~30kΩ of resistance, but in an application where the thruster commander is viable you can likely be pretty loose with the value. To keep the center point the same you would need to split that to a ~15kΩ resistor on either side.
Note that very little current needs to pass through the resistors (on the order of <0.5mA), so they don’t need high current ratings. That said, keeping the center point aligned would require them to at least have quite similar values, which may require trying a few different pairs, or getting ones with high precision.
Analog components can be somewhat variable, and there’s a bit of tolerance built into the thruster commander’s input handling, so if you need an exact output signal range then you’ll likely need to run your own microcontroller or Arduino setup + code to do so (as Tony suggested), but feel free to follow whichever approach is more straightforward for your requirements, budget, and skill set 
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