Well, my design for a cheap, mostly plastic rotator for small loop antennas works. It took me a while to get this built.
Two years ago, I came up with a design for a lightweight DIY rotator for loop antennas. My idea for a mainly plastic rotator was intended to turn wideband or small loop antennas under wireless control. If you read the original article, you can see above the final prototype of that design.
I bought all the parts way back when, but they have been sitting in a project box collecting dust. With my present project to build a multi-turn STL, I figured it was time to put the rotator together. So, I just did the “smoke test” and to paraphrase Galileo: it turns! Here is a video demonstration of the build.
The basic design is a plastic box that sits on a 1.5″ ABS pipe mast. Two Lazy-Susan bearings are attached to the top and bottom plates of the box, and then to the mast with some plastic collars. Then, two plastic gears connect the mast to a DC motor (front left) and the multi-turn potentiometer (back left) with timing belts.
When in action, the plastic box turns around the mast. My loop antenna can be mounted on the top plate of the turning plastic box. Some quarter inch threaded rods hold the assembly together. A NodeMCU microcontroller (right) runs the motor and reads position from the potentiometer. The box just needs 12 VDC. My rotator shows up on the home network and all commands are sent with WIFI.
Originally, I was stumped on how to actually mount all this stuff in a box. But then I realized I could just build onto the top and bottom plates, and attach sides to the box later.
Mostly Plastic Rotator Bill of Materials
So, did I meet my $30 objective? Let’s see. 3RPM DC motor ($7), multi-turn potentiometer ($3), NodeMCU with motor shield ($5), lazy-Susan bearings ($7), GT2 belts and pulleys ($8) – adds up to $30 plus shipping for purchased parts. 3D printed parts and hardware – another $10.
I failed to meet my budget objects, but US$40 for a small rotator isn’t bad. Plus, designing and building this thing was a lot of fun!
By the way, the bearings are 4″ square and the whole box is 8″ by 6″. For an STL, you can add another top section for turning a tuning capacitor which I will do.