Laptop bracket

This is an other little project related to my buddy Eric’s new boat. The boat is equipped with PC-based chart plotter as was its predecessor. In this iteration were using a 19 inch monitor mounted on the dash and connected to a Panasonic toughbook cf27 stowed securely in the cudd. The securely part is where this device comes in.

I’m not absolutely sure that this particular picture is worth a full thousand words. I’m afraid that those who have not seen it in person may only see plywood and screws and not work out quite what is. However it definitely is secure stowage for a Panasonic toughbook cf27. The concept is based on a 1970s style wall mount magazine rack. The pocket is interference fit for the laptop and lined with polyester felt, the felt is in turn glued down with silicone caulking. The front and rear panels feature a cutaway which allow a person to get a good grip on the laptop with one hand and pull it out. The whole pocket tips outward at the top by an inch and a half and is a further uniform inch from the bulkhead to allow for one-inch poplar mounting rails on the inside as well as a space so that cables can pass fully behind. The laptop drops in handle down screen side out, this leaves the rear panel connectors facing upward for easy access and the power switch exposed in the cutout on the right side which is consequently easily reachable through the cudd door.

The cf27 is at this point more little bit dated and can only handle Windows 98. It’s not going to make it through another technology revision but on this occasion the lateness of the season when the boat came together necessitated a quick and dirty approach which minimized reinvention. The machine happily run seaclear which is all that’s really required of it.

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Power inverter

here’s a quick project I worked up yesterday, no I didn’t build the power inverter, just the bracket. Disappointing I know. I’m whipping up a few appointments for my buddies new boat so that it will be ready for the upcoming dive season. This power inverter is to be the power supply for the navigation system monitor and it came fully equipped with no mounting facility whatsoever. I’ve rectifyed the oversight with a little bit of plywood and a little bit of aluminum. The plywood is sealed on the edges with epoxy, possibly that will keep it from delaminating in the humidity but if not it gives it a decorative gloss. The washers on the mounting holes are also epoxied in place for easy installation. In addition to the obvious aluminum strap the inverter is also mounted to the plywood with double sided foam tape. The tape provides a mounting which is impervious to slippage and the aluminum strap renders it equally impervious to cumulative failure of the adhesive. The aluminum strap is also lined with the fuzzy side of adhesive mount Velcro to protect the inverter from abrasion and all hardware is of course stainless steel. This is hardly a high-tech project but I think it came out kind of pretty!

Scallop gauge

This is a small project I completed recently. Very simple really, requires no explanation, but I haven’t posted anything recently so I’ll explain it anyway. The only part that’s not obvious is what the heck this thing is, it’s a gauge for measuring scallops, not because I’m that bored but because there is a size limit on those babies. A word on material selection (it has no moving parts what else will I talk about) since the device is continuously exposed to seawater corrosion resistance is of paramount concern. Dimensional stability is also important since it is after all a measuring tool, so I went with 5/8 inch thick polyethylene (plastic cutting board from Walmart) it’s cut from a pattern made from Bristol board and traced onto the plastic with a permanent marker (the thin one I use for marking CDs) not much else will mark on polyethylene. This approach allows me to commit my precise measurements with a sharp pencil and X-Acto knife then trace the edge generously with the marker leaving a keen edge down the outside of the Mark to follow with the jigsaw. This also allows me to easily make two identical pieces and store the pattern against future need. The device features dual apertures in both 75 mm and 100 mm to serve in both my local scallop fishing zones and double ended attachment holes(you don’t really want to bring anything diving that you can attach.) I think it’s going to get clipped on to my pressure gauge, a nice handy place for it, but the truth is I tend to change my mind about such things after I try it.

Beautiful and terrible as the dawn, treacherous as the C

It has been my intention for sometime to learn microcontrollers. These days there’s a microcontroller in everything from toasters to paperweights except for my projects which so far remain as stupid as a wooden birdhouse.

Some time ago I decided to go with microchip’s PIC microcontrollers (and when I say sometime I mean years.) At this point I can’t say I actually remember why I settled on the PIC but it seems to be a fine low-priced unit with excellent support within the hobby community, that will do the kinds of things I’m interested in doing. (Hey wait maybe that’s why I picked it the first place.) I never did get around to doing anything about my intentions until several weeks ago on the occasion of my annual Christmas bonus coming to pass. I decided to seize this brief moment of financial liquidity and acquire for my very own a PIC development kit.

The PICDEM lab called out to me. I had always intended to be frugal and acquire individual components for my autodidactic journey into microcontrollers however as I absorbed the suitability of the PICDEM lab I realized it was largely the non-trivial task of determining which bits and pieces I would need which prevented me from starting this journey all this time. So I put aside my frugal ways and placed my order.

It was always my intention to do my microcontroller programming in BASIC as I’m already familiar with that language and it’s always served me well. That option is indeed possible but alas it’s not the road I’m on. It seems that C is the unofficial language of PIC microcontrollers (or maybe it is official), possibly most microcontrollers.

But that’s not so bad, as my journey continues I’m more and more convinced that C is indeed the most appropriate language for the task. When you’re coding for hardware that you built yourself from scratch the benefits of hardware abstraction run a bit thin, best to remain intimate with your ports  and your peripherals.

People say that C code is difficult to read, the meaning is obfuscated intention is not made clear. I can assure you that the people that make these observations, shit you not. I assumed I would just “pick it up” as I went through the tutorials, after all C is not that different than BASIC  math is math , logic is logic many of the important functions are the same  IF, FOR, WHILE, they’re all in both languages, how hard could it be?

Well I didn’t get very far before my optimism was quenched by my ignorance and I was forced to resort to additional educational material in order to understand example code. fortunately C is a mature language and their is a great deal of resources both online and hardcopy for those seeking to learn it.  Unfortunately, pretty much all of these resources assume you’re working on a PC, usually a PC running Linux (I have a love-hate relationship with Linux) and as such the example code relies heavily on standard I/O. Microcontrollers, of course, have no standard I/O. so my journey branches again. I found myself a lovely little piece of software called codeblocks, a nice cross-platform C development  environment.  Here I am, learning a whole branch of computer science that I did not intend. oh well, you can never learn too much right?

So that’s where my spare time has gone the last month or so.

BASIC

What’s been occupying my time lately is little software project, that got set aside some time ago and with the change of seasons I’ve taken up the challenge of finishing it. As last year’s hunting season approached my good buddy Eric decided he wanted to get himself a shooting chrony, these units are pretty much the de facto standard for low-budget chronographs, there robust, reliable, for the most part value priced.

On the other hand the basic design is pretty much unchanged since the late 70s when the first one I encountered was purchased. Although the physics of measuring projectile velocity hasn’t changed very much since then the user interface is a tad dated and in my opinion a bit of a kludge by modern standards.

So, Eric and I dreamed a little dream. how about we hook it up to a laptop and write some custom software that will display all the information it produces in a coherent modern fashion. this is how my most recent journey into basic began.

I first got my hands on a computer of my own at the tender age of 12, that would’ve been in 1985. At That time of course the computer in question was a Commodore 64  which came equipped  the Commodore basic  2.0 interpreter.  With practice and much manual reading I became adept at making it do what I wanted , occasionally even something useful! but as the Commodore became obsolete I found it difficult to roll my skills forward. like the rest of the world I transitioned to PCs and chairman Bill did not encourage mere mortals like myself to undertake the writing of software. I’ve amused myself QBasic over the years but there’s really little chance of impressing your friends that. But the chrony project which was originally to be written in QBasic, spawned a new bout of research into the possibilities and revealed the existence of Visual Basic 2010 with the express edition now published for the benefit of mere mortals free of charge! wow , almost like the 80s.

the idea was to stay with some flavor of basic and leverage my knowledge of Commodore basic which I seem to still have full command of, burned as it were into my teenage mind.  However, modern Visual Basic (as those who use it know) is a whole different animal. I suspect if I taken on C+ I would’ve been no less prepared, not to imply that I was prepared. In  the old days I did what is now called unstructured programming, back then it was just the only way to do it. but there’s no room for unstructured programming now, I’m tempted to say one is made a slave to structure a program is no longer a list of instructions as I learned in the old days but  has been reduced to a collection of events with a  chunk of code belonging to each event. All these chunks of code give the impression that they’re not tangibly related each other and much of the time they’re not aware of each other  or able to communicate with each other, which is somewhat unsettling to that 12-year-old that used to know what he was doing.

Ultimately this journey will lead me to a place where I can create cooler stuff than I could have otherwise but I can’t shake the feeling that I’m not in Kansas anymore.

Imaginary straight lines

A recent episode of mythbusters I enjoyed recently gave me some pause for thought. Jamie and Adam applied their special treatment to the idea that people are unable to walk in a straight line while blindfolded. Being a scientifically minded man it’s difficult for me to agree they “proved” anything with a sample size of two however they did conduct compelling demonstrations in one’s ability to walk a straight line blind folded is quite limited.

Seemed quite obvious to me that this information be important in my daily life in the future. Knowing that the human vestibular system is much more limited than I had in the past assumed is very much of value to me. When I met the great outdoors find myself arriving at a place I didn’t quite intend it isn’t lack of experience that got me there, nor is it stupidity. I’ve now seen with my own eyes the traveling in a straight line without obvious visual reference absolutely requires a well thought out technique, there just isn’t any way around it.

This is of particular interest to me in the field of diving. Those who do not dive may be surprised by how much less one knows about where one is, how one got there, and how to get back, when one is traveling underwater. To complicate matters, discussing the subject of underwater navigation with seasoned divers is liable to raise the same attitudes one might counter discussing becoming lost in the woods with Northern fur trappers.
Of course the major dive training agencies do provide training in underwater navigation however the techniques that are put forth always struck me as somewhat inadequate. I’ve studied orienteering in the past and although the underwater navigation techniques are an adaptation of the same tactics they seem to fall far short of achieving the same goals.

The mythbusters recent testing would seem to support my previous opinion that the current state-of-the-art in underwater navigation is more of an art than the science your local PADI dive instructor would have you believe.

GPS surface float

Today I’ve corrected the problem of having this poor neglected empty blog sitting on the Internet sharing nothing with anyone and have published a hopefully useful description of my latest project the GPS carrying divers surface float. Hopefully I’ll be able to test it before winter comes. In principle winter diving is a fine activity as your wetsuit keeps you toasty warm in the cold water, in practice however one must strip down to one’s basic essentials leaving one’s warm wetsuit to re-don dry clothing and exposing one’s bare back to the snowflakes, raindrops, and frosty breezes. I’m afraid it’s just not my thing, one day I’ll be able to invest in a dry suit and such concerns will trouble me no more.