Public Lab Research note


Mounting and deploying a Mini Pearl Logger

by cfastie |

Read more: publiclab.org/n/15855


A Mini Pearl Logger is built by combining several off-the-shelf electronic components. Assembling a Mini Pearl Snap Logger Kit involves sliding DuPont wires onto header pins and takes about 15 minutes. Assembling a Mini Pearl or Mini Pearl Pro Logger Kit requires soldering wires between the components. In either case, the result can be sprawling and floppy.

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Figure 1. An assembled Mini Pearl Snap Logger. Slide-on DuPont wires connect five components and the battery case.

All of the electronic modules in a Mini Pearl Logger have exposed pins and solder points, so to avoid shorts, the modules must be protected from one another. Stabilizing the assembled logger is also useful because it prevents motion at the wire connections which could break solder joints or loosen DuPont connectors. To address these issues, I designed a mounting plate for this logger.

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Figure 2. The Mini Pearl Mounting Plate makes it easy to stabilize a Mini Pearl, Mini Pearl Pro, or Mini Pearl Snap Logger. The components are attached with twist wires through the holes. Only the round holes are needed for the Mini Pearl Snap Logger, and the square holes are also used for the soldered versions. Triangular holes are for mounting the plate to something or for wire passthrough.

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Figure 3. Wires can be twisted under the mounting plate to hold the components securely. The yellow elastic cord will hold the battery case against the plate.

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Figure 4. Four modules held to the plate with twisted wires. This is a completed Mini Pearl or Mini Pearl Pro Logger with the Log-a-Long Timer option.

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Figure 5. A mounted logger fits inside a 16 ounce sour cream container. With the sensors inside the container, the logger is weatherproof, but not waterproof. A short slit in the top allows the wires for sensors to pass through for sensing humidity, light, etc. The slit can leak, so the container would be placed under cover.

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Figure 6. The mounted logger fits inside a 28 ounce peanut butter jar. This is a plastic jar with plastic lid and the seal is not necessarily waterproof. Two Hull Penetrators have been installed in the lid to pass cables to sensors. This can make the enclosure weatherproof but not reliably submersible. The sensor would have to be independently weatherproofed.

A 3D-printed mounting plate is included with each Mini Pearl Logger at the KAPtery.


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1 Comments

Oh no! I recycled the sour cream containers. We'll have to go eat some sour cream now. :-)

I'm hoping it'll be possible to attach these to a stake and allow a waterproofed sensor to trail down into water, to avoid having to completely waterproof this thing.

More soon!


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