Lesson learnt on stepper motors

A project log for SATRAN - Satellite Tracking Antenna

3D-printed, wifi-enabled and android controlled antenna rotator.

Daniel NikolajsenDaniel Nikolajsen 01/22/2021 at 06:120 Comments

I am now in the final tweaking stage of the project. Getting sensors to work mostly without any glitch, and tuning the stepper drivers to make the torque as good as possible without overheating or breaking anything.

For almost a full day I struggled with getting any decent torque from my stepper motors. The A4988 driver has a built in circuit to limit the current with a trimpot to adjust it, but no matter what I did the motors gave off some crazy whining sound and never took more than about 200mA, and were so weak that I easily could halt the motors with my fingers.

But then, after a fresh cup of coffee, I read the datasheet for the motor and realised... Resistance! The motors I had were 10 ohms. So I switched to 2.8ohm motors instead, and bam! A full 1 amp current. Now the rotor should be able to turn the antenna without any issue, but the exact specs are still to be tested...

We're getting somewhere!

Also the response I have gotten from all over the world has been amazing, I cant thank you all enough. From more or less being unemployed due to covid last year, I am now working day and night to finish the design. Lots of people are requesting to buy the kits, and if you havent already - subscribe to the newsletter on my site to get reminded when stuff gets released, because the first kits and circuit boards will probably sell out in minutes. Also, thanks to you and others who have donated to the project I will try my best to keep as much as possible under open source, including the android app I am developing.