The general idea is to build a curtain opener, using some kind of motor connected to my arduino. Which will cause the pulling-functionality...

So the following options are :

1. DC motor

I feel like this is the least preferable one, since of it's low torque

2. Servo motor

If I "hack" the servo & cut off the potentiometer. I should be able to make it go in to two directions, in 360 degrees and still keep the power of the torque, I think?

3. Stepper motor

This is probably the most recommend one for the functionality I'm trying to achieve but, stepper motors are quite big, maybe a bit too big and quite pricy from what I've seen.

So, to sum it up. I could use a DC-motor, but I don't think it will be able to pull the curtain rope with enough power. I could also use a stepper motor, but it looks too big and heavy for the environment I'm using it in. So, would a "hacked" servo, be an OK solution?

Maybe I'm not seeing other possible problems here that might play a role...


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    \$\begingroup\$ A dc motor can have very high torque with the right gearbox. \$\endgroup\$ – Jeroen3 Aug 13 '18 at 13:38
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    \$\begingroup\$ A servomotor is just a DC motor with a gearbox. Such motors (without the servo electronics) are readily available. "Gearhead motor" is a useful search term. \$\endgroup\$ – Dave Tweed Aug 13 '18 at 13:49
  • \$\begingroup\$ Mostly they seem to use tubular DC motors with gearboxes.. based on what I've seen from Chinese vendors at trade shows. Limit switches built-in. \$\endgroup\$ – Spehro Pefhany Aug 13 '18 at 13:49

A DC motor is likely up to the task, having functionality for up, down, stop, and naturally automatic stop at top and bottom with some limit switches or current sensing. You can get DC motors of all sizes and use a gearbox in addition to whatever pulleys the system requires if necessary to provide more torque and voltage/pwm control to control speed.

If you are making "smart curtains" and require precise digital control of the curtain's position, that would be the application for a servo or stepper motor. Something similar could be achieved by calibrating control of a DC motor, but it wouldn't be precise. Servos and steppers require more complicated control mechanisms, but if the device had a microcontroller in it anyway, that might not be a big deal.

First thing you should figure out is roughly how much torque you need to move the curtains at the greatest speed you will want to. You can use that to start comparing the abilities of motors in that class. The voltage you have readily available may be a factor too.


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