2024-03-08 (F) Weekly Summary

The USB port and leaderless motors never sat well with me. I looked around and found battery holders and motors with header-type pins, so when people buy this kit, they can install the components and then plug in the electrical connections.
2x2 header for motor and power

The first boards arrived. I taped a AAA battery holder to the bottom and mounted the motor with M3 bolts. However, the shaft hole was too small and caused friction. I used 35mm long bolts as legs and the unit sat level on a table. The speed controls worked fine, but low speeds were hard to judge due to the friction.
First PCB prototype

The PCB I ordered only had the control circuit, so I needed a platform below the board to hold the motor and spinning magnets. I used my wooden proof-of-concept as a guide and made the parts. I assembled two boards for metric magnets and one for 1/2" magnets. The thicker magnets worked better to connect with my stir rod.
Spinning magnets

The group discussed the PCB board's design, and we chose a broken lightbulb image for its less-than-perfect look. I picked an AI-generated image with high contrast and edited it using GIMP, removing the glass shards near the break.
A broken light bulb is less-than-ideal

I made changes to the schematic and layout, re-adding a USB port, using spring-loaded screw terminals, and changing the motor footprint. I designed the board to accept one or two battery holders. For the lightbulb image, I used GIMP and QCAD to create a usable DXF file.
Stir plate in a light bulb PCB

I was unsure how to make the motor and magnet mounting hardware. I considered cutting the parts myself, but that would not be efficient or cost-effective. Instead, I ordered shapes cut by the PCB manufacturer. I had some trouble with the earlier prototype because the hardware crowded the mixing area, so I connected the motor to the top and moved all the components to the same side. After disassembling the motor bracket and reconnecting everything on the other side, I could place large vessels on top without interference.
The backside is the best side for stirring

The rest of the summary posts have been arranged by date.
First time here?

Completed projects from year 1
Completed projects from year 2
Completed projects from year 3
Completed projects from year 4
Completed projects from year 5
Completed projects from year 6
Completed projects from year 7
Completed projects from year 8
Completed projects from year 9
Completed projects from year 10

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