3D printing

Cloud monitor MKII (now with POE!)

After building the Mark I cloud monitor, I realized that I really wanted something with power-over-ethernet (POE). The cheap network adapters that I use typically have an HR911105 (or similar) RJ45 connector which is not compatible with POE. I’ve looked but have yet to find any of these adapters with POE, so I decided to hack my own together. In theory, it should be easy… What you need 2x MLX90614 thermopile sensors 1x Arduino Nano 1x W5500 ethernet adapter (I…

3D printing

Building a network-connected cloud sensor (MKI)

I’ve wanted to build a cloud sensor for years now, but never actually found the time to do it. So, after seeing IR sensors for something on the order of $5 a piece, I ordered a couple and thought that I’d give it a shot. This has undoubtedly been done by lots of other people, but I thought that I’d share some simple instructions on how to build your own. The theory We could get in to the theory of blackbodies (maybe later), but it is sufficient to say that… Clouds are warmer than a clear sky. The infrared spectrum of an object can tells us something about its temperature. If you can measure the temperature of the sky, you should be able to say something about whether it’s cloud-free or not. To measure the temperature we need some sort of contact-less thermometer that can be pointed at the sky (and ground, more on that later). What you need 2x…

3D printing

A 3D printed Ronchi tester

The situation was that there were three telescopes. Each with the same 20″ cellular mirrors but one with a slightly different cell than the other two. Two were easy to collimate while the third one could never be fully collimated. It appeared that there was a bit of astigmatism that was preventing easy collimation. So, the problem was how to quickly test a mirror for astigmatism. A Ronchi test was suggested but I didn’t have a grating or even a tester. What to do? Print one? The first step was to find a grating. Since I couldn’t wait for a proper grating to arrive, I decided to try to print a 100 line/inch grating on transparency film with a laser printer. The second step was to make something to hold the grating and a light source. First I cobbled together something out of scrap plywood and, although it worked, it looked like something that the dog dragged in. It was…

3D printing

A cheap, low-light IP finder ‘scope’

My academic work focuses on meteors. Visual (and sometimes radar) observations of faint meteors. For this, the general requirement is a sensitive video-rate camera with a moderate field-of-view. The traditional solution (after eyes, photograpic plates, vidicon, etc. ) was to use an analogue security camera with low-light sensitivity. For many years, this was the Watec 902 series. They are good with resolutions of 720 lines on an (up to) 1/2″ CCD chip. Their sensitivity is estimated at down to levels…