K1 project page INCLUDING publically-available files

Genesis

As promised, here it is!

http://www.denninger.net/rebreather/rebreathers.htm

This page contains somewhat of a "web log" of the K1 project. Not all of the detail that is in the posts here is represented - but most importantly, the files for the ExpressPCB schematic and PCB layout are present, as are the files for the Parallax BS2Pe microcontroller.

These will allow basically anyone to reproduce the electronics that run on the Parallax chipset. While this is not the chipset I intend to use in the final version of what I'm building, it definitely works, the hardware is compatable with the ZX chip (and the BX) that I am using, and for someone who is looking for a way to get started, some example hardware and code, or even something that can be used as a controller (with testing and tweaking of some of the constants - e.g. injection intervals, etc) or a 3-cell PO2 monitor it may be just what the doctor ordered.

The files in question are published under the GPL and thus can be not only used but redistributed. For personal use this presents no constraints of any kind. Commercial use is permitted, but please be aware of the constraints that come with doing so as defined in the GPL, as my publication under it is very deliberate and with full understanding of the consequences.

Updates will be posted on the page as progress continues....

Enjoy!

__________________
"A venturesome minority will always be eager to get off on their own, and no obstacles should be placed in their path; let them take risks for Godsake, let them get lost, sunburnt, stranded, drowned, eaten by bears, buried alive under avalanches - that is the right and privilege of any free American."
http://www.denninger.net
http://www.diversunion.org/liability.htm - Fix the Diving Cert racket

dwessels

This is really cool, thanks for sharing with everyone.

Denzil

Genesis

You're welcome - I'm working on the T-pieces and scrubber can now.... got a date back on the handsets - the handset cases should be here in a couple of weeks.... critical path right now is (oddly enough) the Fischer connectors.

__________________
"A venturesome minority will always be eager to get off on their own, and no obstacles should be placed in their path; let them take risks for Godsake, let them get lost, sunburnt, stranded, drowned, eaten by bears, buried alive under avalanches - that is the right and privilege of any free American."
http://www.denninger.net
http://www.diversunion.org/liability.htm - Fix the Diving Cert racket

Scuba_Vixen

Once you get the handset pieces back, ou may want to do some pressure pot dives with them before you put anything into them.

Making a 1ata housing that seals perfectly at 300' + is *not* an easy task. ...... Mine seems to come up with maybe a quarter teaspoon of water in it about once every third time I open it and close it (simulated battery replacement) and test it again.

Small modifications and more testing continues ......


Darlene

Genesis

Yep - there's a fair bit of torture testing that I'm going to do on dry land before it goes in the water Well, much more than a pot's worth of water anyway

__________________
"A venturesome minority will always be eager to get off on their own, and no obstacles should be placed in their path; let them take risks for Godsake, let them get lost, sunburnt, stranded, drowned, eaten by bears, buried alive under avalanches - that is the right and privilege of any free American."
http://www.denninger.net
http://www.diversunion.org/liability.htm - Fix the Diving Cert racket

Genesis

Guess what's here?

Waiting on Fischer..... oh man, I'm like a kid in a candy store!

Got 10 guys and gals...... VERY nice work, on budget and ahead of schedule.

Who said machine shops all suck?

Attached Images

DSC02041.JPG (142.6 KB, 1320 views)

__________________
"A venturesome minority will always be eager to get off on their own, and no obstacles should be placed in their path; let them take risks for Godsake, let them get lost, sunburnt, stranded, drowned, eaten by bears, buried alive under avalanches - that is the right and privilege of any free American."
http://www.denninger.net
http://www.diversunion.org/liability.htm - Fix the Diving Cert racket

Scuba_Vixen

Very nice indeed!

Now the real fun begins


What are the dimensions on your cases, BTW ?



Darlene

Genesis

Finished dimensions are 5 x 3-3/4 x 2-3/8. A bit bigger than I'd like but its SSSTRRRROOONNGGGG. I'm going to try running one of them over with my Suburban, dropping a few tanks on it, etc - part of the reason I ordered 10 was to see what sort of torture I could put it through and have it survive. After all, we know that people DO drop things on dive gear, especially on boats! The design goal was a 10ATM pressure rating (~330fsw) with a 2:1 safety factor. I don't have a good way to test to destruction on pressure if it goes as far as I think it might. I'm actually more worried about the Fischer connector's internal seals failing before the case does, but quite honestly if you're going to go much beyond 330 IMHO you probably want to think about filling the entire silly thing with silicone oil and forgetting about compression problems.

I'll definitely post some torture test pictures on the web page - those ought to be fun...

There are 45 degree chamfers on the bottom, and four holes parallel to them for standard bungie cord (for your wrist if you want). The select button mounting holes are 1/2" threaded; I have to turn up the bosses for that along with the buttons themselves; I've already got the magnets. If this thing proves out I'll have a run of the bosses and buttons made up - doing 20 of each was damn expensive - it added close to 50% of the cost of the handsets as a "small order"! I'll make 'em by hand for the prototype for what various places wanted for those.... From what I can tell the setup on CNC jobs is basically where all the money goes when you're talking plastics - tooling isn't that expensive as plastic doesn't chew it too bad, and the material isn't that expensive either.

The prices I got back on Q100 orders on the handsets were VERY attractive.... Here's hoping the design proves out because then I have a baseline for a production run and know what the costs will be.

After a LOT of prototyping and soul searching I've decided to go with a 4.5ah standard 12v NiMH can for power, with an E/O cord and switch on it. I understand all the arguments about small is better, tiny is even more desireable, but the more wierd stuff you have the more trouble it can be when something breaks - and I decided I really wanted a hard power switch.

I've made some changes in the code so that you can actually shut the thing off while diving and it won't lose its idea of when you started or how deep you were and are. That is, if you suspect an electrical fault you can turn off the electronics entirely with a hard switch on the cannister, check what's up (e.g. against the VR3's "4th cell") knowing that there is NO electricity running around inside the unit and then turn it back on and it will know you are diving and not lose any of its information! Instead of stashing that data in RAM, its going in the clock chip - which has a lithium battery backup good for several years. This necessitated just one small change in the board (the voltage divider for V+ sense), a constant change in the code, and changes the solenoid to be +12V drive. The latter is of benefit mostly due to lower current draw. It also puts primary overcurrent protection in the cannister, power goes to the head, then goes down to the handset for regulation. A 4.5AH can should provide close to 100 hours of "power on" time on a charge, there's no need for anything fancy there (just turn it off with the switch when you want) plus it uses the same charger you'd use for your dive light. This makes everything but the can lid common between your light and Rebreather power pack - reducing what you need to buy and carry for spares.

What's left is the Fischer connectors (ordered but not yet here) and making the revisions to the CPU board to go in the case as well (I've decided to put it in there along with the LCD); it needs to be redesigned so the switches are physically present on the main CPU board.

I'm bummed the Fischers aren't here as I can't pressure test the thing until they are, since there's a nice big HOLE in the side where it goes right now...

I am still undecided on exactly how I'm going to handle a HUD. I know I want one, but I'm torn between a very simple analog type and something more complicated. I know I don't want a complete second handset running it for a whole host of reasons. The ideal would be a completely separate electronics implementation that would run on its own power and share only physical connections to the sensors - nothing else - with a magnetic "calibrate" switch accessible through the housing. That one's still up in the air and may remain there until I get the rest of this together and dive it a bit to see what I really want and need....

The cannister pipe looks good too. The cones from the standard rebuild kit fit perfectly, seal to the pipe when the cartridge is locked in place, and provide me with a water trap in the cannister as well as the flow homogenuity necessary.

I have to bend some metal for mounting the can and mount points for cylinders on a standard backplate, cut and fit end caps for the cannister, make mounting brackets for the sensors plus make the T-pieces. Intent for the prototype is to use OTS lungs made from MSR bags. Manual adds for dil and O2 will be adapted BC inflators initially. I am not planning on an ADV on the first go, mostly because its yet another potential failure point. If I get unhappy about the task loading I can always add one easily enough.

That's pretty much it. I've acquired an older KISS BOV for a mouthpiece and am using the O2ptima breathing hoses, which should be ok with a cross-shoulder cannister.

Looks real good at this point....

Next up for it after the original build will be a conventional axial cannister mounted between the two tanks that takes loose fill; that will likely necessitate a larger bore breathing hose ot keep WOB under control due to the longer path length. We'll see.

If this thing proves out I'll have lungs and T-pieces made up in quantity along with a bracket system for the tanks and scrubber to go on a standard 11" bolt pattern. That way you can use it with a regular plate or if you prefer a softpack like a DiveRite Transpak.

I've got quotes on injection molded T-pieces already that are quite competitive if I'm buying 100 of them. The mold charge is murder for small quantities though so the prototype is going to have those made out of what will look decidedly like a garage shop deal - mostly because it will be.

__________________
"A venturesome minority will always be eager to get off on their own, and no obstacles should be placed in their path; let them take risks for Godsake, let them get lost, sunburnt, stranded, drowned, eaten by bears, buried alive under avalanches - that is the right and privilege of any free American."
http://www.denninger.net
http://www.diversunion.org/liability.htm - Fix the Diving Cert racket

Genesis

Fischer got part of their order here; the rest will be here tomorrow. O-ring for the case which was planned for 2-242 fits well. Need to either build a pot (I have a junk AL80 but haven't found someone with a big metal cutting bandsaw to hack off the top yet - there's not much in the way of machine shop saround here that will take this kind of "short order" thing) or someone with a pot to put it to the test pressure-wise, but I can't imagine it will fail, all things considered. If I don't find that soon I'll just take it out to the Nipple (~500fsw), stick it on a fishing line with a weight, and lower it to the bottom! Nothing like believing in your design right?

Here are some interesting torture test results.... thought you'd like 'em....


Car .vs. handset, weak side up, all weight supported by the handset. Result: PASS; note O-ring seal still visible (the lid did NOT distort enough to break the seal.)


Cinder block from 8' .vs. handset, dropped repeatedly without regard to which way the handset was facing or the block landed. We know divers are SO considerate on boats, so it would be nice to know if the handset will survive outrageous insult. Result: PASS.

R3.0 controller boards are out for fab, expected back end of week. I expect to have a working handset and head board in < 2 weeks. A mini-lathe has been ordered and should arrive next week so I can make the handset button bosses and buttons themselves; I had those quoted and it was silly expensive, plus, this will come in handy for other "necessary bits" as things continue forward.

Looking real nice.....

I still have 9 (usable) handset cases; the one I'm using for torture testing is still servicable but looks pretty bad now Figure there'll likely be a few extras if anyone needs 'em in a month or so....

__________________
"A venturesome minority will always be eager to get off on their own, and no obstacles should be placed in their path; let them take risks for Godsake, let them get lost, sunburnt, stranded, drowned, eaten by bears, buried alive under avalanches - that is the right and privilege of any free American."
http://www.denninger.net
http://www.diversunion.org/liability.htm - Fix the Diving Cert racket

diverklondike

Looks great... but note that when the can we kill a Meg parts were done.. they were done on the road and not the grass....

Best of Luck!

Mark