Archive for month: June, 2015

A brief overview of my recent magnetometer experiments…

June 30, 2015 | Amateur Science, Arduino | By: Mark VandeWettering

If you follow me on twitter (@brainwagon) you’ve undoubtedly seen a few mysteriously short tweets about experiments I’ve been performing on magnetometers. It’s hard to give any meaningful context in just 140 characters, so I thought I would dump a short overview of what I’m doing here, in the hope that I’ll turn it into […]

On quadcopters…

June 18, 2015 | DIY Drones, Quadcopter, Rants and Raves | By: Mark VandeWettering

I’ve been having a bit of fun with my DJI quadcopter lately, but there is something that is annoying me and stressing me in the back of my head, and that’s surrounding the legality of flying quadcopters. Basically, it’s impossible to determine with any certainty whether flying your quadcopter in any particular place is legal. […]

HOWTO: Print a cheap Ronchi Screen…

June 15, 2015 | Telescopes | By: Mark VandeWettering

If you are going to test your telescope mirror, you will sooner or later need a Ronchi screen. The best Ronchi screens are usually made on glass, with the black lines being formed by metal or chrome deposition. Another way to make a good screen is by film reduction: you print a large screen and […]

Another lap around the telescope workshop..

June 13, 2015 | Telescopes | By: Mark VandeWettering

For the second week in a row, I carted my body down to the Chabot Science Center and attended the Chabot Telescope Makers workshop. My intention was two-fold: I was going to extract the mirror from a little 6″ telescope that I had found at a garage sale and purchased for a mere $15, and […]

For a 6″ f/12 Newtonian, a sphere suffices…

June 10, 2015 | Telescopes | By: Mark VandeWettering

I mentioned that I was searching for my 6″ f/12 that I made years ago. Still have not found it, but I was wondering: how good is a 6″ f/12 sphere? I recall hours of polishing to try to get to a nice, smooth null, but don’t remember if I ever quantitatively figured out how […]

Treasure hunting in the garage, along with some mirror test analysis

June 9, 2015 | Telescopes | By: Mark VandeWettering

As I mentioned before, I’m trying to get back into telescope making, a hobby that I haven’t been involved with for a few years. The fruits of more than a decade of telescope making are in my garage: I have a bunch of supplies and utilities that i have sort of lost track of. Somewhere, […]

Ronchi code now on github…

June 8, 2015 | Telescopes | By: Mark VandeWettering

I updated my old 2001 Ronchi test code to support arbitrary conic surfaces, and then uploaded the code to github. My current 12.5″ project is an f/5 paraboloid: If we were interested in making a spherical mirror, we’d have these as patterns: Why bother writing this code? I’m actually interested in trying to acquire images […]

Checking my own Ronchi test code…

June 8, 2015 | Telescopes | By: Mark VandeWettering

It was a long time since I wrote the code that I used for Ronchi code, and while I had some confidence in it, I wasn’t 100% sure that I had verified it. So, today, I took a copy of Ronchi for Windows 2 (I downloaded it from here) and set it up to predict […]

Nifty telescope idea…

June 7, 2015 | Astronomy, Telescopes | By: Mark VandeWettering

Since I stopped actively working on building telescopes, there have been numerous bits of technology that are now widely and cheaply available, and that can be used to implement new, interesting functionality. In particular I hadn’t considered that the same kind of sensors which are used to control quadcopters could be used to determine the […]

Dusting off old Ronchi Testing Code…

June 7, 2015 | Astronomy, Telescopes | By: Mark VandeWettering

At the Chabot Telescope Maker’s workshop, we make a lot of use of the Ronchi test. It’s great for figuring out gross defects and problems with your mirror. Back in the day, I wrote a simple program to generate Ronchi patterns for a given parabolic mirror. Here are six Ronchi patterns generated by my code […]

Flying at Lime Ridge Open Space…

June 7, 2015 | Quadcopter | By: Mark VandeWettering

It was a warm and reasonably calm day, so Carmen and I decided to take the Phantom 2 out to Lime Ridge Open Space, where many RC enthusiasts fly. Rather than bore you with 18 minutes of video, I thought I might give you two short video highlights… Without further ado:

An Arduino Powered HF Beacon…

June 7, 2015 | Amateur Radio, WSPR | By: Mark VandeWettering

LB3RE sent me a link to this awesome HF beacon by Anthony, F4GOH and Christophe, F4GOJ that has many of the same features as my (as yet still in-progress) beacon transmitter does. And, of course, his actually exists, so it’s already infinitely more awesome than my idea. I was particularly interested in his very simple […]

Gert’s 2015 Jupiter Campaign

June 6, 2015 | Astronomy | By: Mark VandeWettering

I forgot to mention my chat with Gert, another telescope making regular up at the Chabot Telescope Maker’s Workshop. He’s a skilled astrophotographer and all around interesting guy, and has embarked on a campaign to do some high quality imaging of Jupiter. You can see some of his results here. Pretty nifty stuff. I copied […]

Dusting off some old equipment…

June 6, 2015 | Telescopes | By: Mark VandeWettering

If I am going to get going on this mirror again, I need to dust off and/or build some new test equipment. I never really did make an adequate Foucault/Ronchi tester, preferring to do all my testing at the workshop, but frankly, that seems a cowardly on my part. I suppose I’ll have to figure […]

Telescope Making: a new return to an old passion..

June 6, 2015 | Telescopes | By: Mark VandeWettering

Even recent readers of this blog may not know of one of my old passions: building telescopes. Back when I was ten or eleven years old, I read an article in Popular Mechanics or some such that told how you could build a telescope from scratch, including grinding and polishing your own mirror (most amateurs […]