Electronics parts list

Here’s the start of a list of common bits and doo-dads I use for building electronics projects.

https://github.com/millerlp/parts_guide/blob/master/parts_guide.md

That’s all there is to it.

Preserving equations in Powerpoint when going cross-platform

This is another one of those tricks that I forget how to do unless I write it down. When I move Powerpoint (2010) presentations from my Windows machine to my Mac (Powerpoint 2011), the equations usually get destroyed along the way. The workaround is to turn the equations into images that can’t be altered by the Mac.

For example, here I’ve got an equation plopped into a blank presentation, with the equation editor toolbar.

The equation.

The equation.

The first step is to copy the entire equation and the text box … Continue Reading

A plot of co-authorships in my little corner of science

author year count image

 
Here’s a mostly useless visualization of the collection of journal articles that sits in my reference database in Endnote. I deal mostly in marine biology, physiology, biomechanics, and climate change papers, with a few molecular/genetics papers thrown in here and there. The database has 3325 entries, 2 of which have ambiguous publication years and aren’t represented above. This is by no means an exhaustive survey of the literature in my field, it’s just an exhaustive survey of the literature on my computer.

To make this figure, I first had Endnote export the database to … Continue Reading

Disassembling an ancient Si-Tech dry suit exhaust valve

Experienced cold water scuba divers will tell you that a dry suit is a vital piece of safety equipment, especially in challenging conditions (seriously, they’ll tell you without prompting, and then babble on about their gear until you walk away). Serious divers will also tell you that maintaining your gear in tip-top shape is an important safety issue, and all service should be done by trained technicians (again, it’s like that old joke: How do you know someone is vegan/went to Princeton/is from California? Answer: They’ll tell you. Divers, particularly overweight men with walrus mustaches, are the same way when … Continue Reading

Open Wave Height Logger prototype in the water

I finally got around to deploying a prototype OWHL unit in the real live ocean to log some waves.

The low-tech housing is made of 1.5″ schedule 40 pvc pipe. The pipe snugly fits the D-cell battery holder, while the electronics fit inside the modified 1.5″ end cap.

Components of the housing.

Components of the housing.

Prototype housing

Assembled prototype housing

I try not to rely solely on the tapered threads of the … Continue Reading

OWHL micro SD card current draw tests

As outlined in an earlier post, I found that certain old micro SD cards were performing spectacularly poorly when it came to power consumption because they failed to go into a low-power sleep state immediately after writing data to the card. I recently purchased a few new SanDisk micro SD cards in various capacities to see how they behaved. I purchased 4GB, 8GB, 16GB, and 32GB SanDisk cards from Amazon in November 2014. These were all tagged as “Ships from and sold by Amazon.com” and ranged from $5.99 to $12.99.

The good news is that all 4 cards behaved properly … Continue Reading

Extracting NOAA sea surface temperatures with ncdf4

I’ve written previously about some example R scripts I created to extract sea surface temperature data from NOAA’s Optimum Interpolated Sea Surface Temperature products. If you want daily global sea surface temperatures on a 0.25×0.25° grid, they gather those into 1-year files available at http://www.esrl.noaa.gov/psd/data/gridded/data.noaa.oisst.v2.highres.html. If you want weekly average SST values on a 1×1° grid, you can get those back to 1981 at http://www.esrl.noaa.gov/psd/data/gridded/data.noaa.oisst.v2.html. If you just want a smaller file for a single day on the 0.25×0.25° grid, you can find those at http://www.ncdc.noaa.gov/sst/griddata.php.

Continue Reading

Revised Open Wave Height Logger battery tests

The Open Wave Height Logger is meant to be a submersible pressure logger that will record absolute pressure at 4Hz for several months to give a record of wave height, and ideally do this on a single set of 3 D-cell batteries. I have recently made a few changes to the OWHL software, and discovered a major flaw in my original battery test. As a result, I have begun a new round of battery tests. The hardware and software changes are described here, and new battery test results are shown at the bottom of the page.

I was … Continue Reading

The effect of water temperature on whelk drilling speed

Last year I published a little paper showing how whelks (Nucella lapillus) drill through mussel shells at different rates depending on water temperature. This involved making hundreds of hours of recordings of whelks slowly scraping their way through the calcium carbonate shell of Mytilus edulis mussels in different water temperatures. The video above includes two examples of those recordings from two different snails of the same size, highlighted as red dots on the graph in the video, one taken at a water temperature of 9°C (48°F) and the second at 17.5°C (63.5°F). What you’ll notice … Continue Reading

ffmpeg time lapse notes

ffmpeg is a movie-encoding command line tool that is also useful for capturing and assembling time lapse movies, particularly using webcams. Below are some example commands to get it to do stuff. It is run from a terminal command line on Linux, OSX, and Windows. You will probably want to add the location of the ffmpeg files to your system PATH so that you can invoke ffmpeg from any directory.

The code shown here is specific to Windows 7 and later machines, so some commands will not work on OSX or Linux. Specifically, Windows uses the “dshow” option for … Continue Reading

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