K1 project page INCLUDING publically-available files

Genesis

I tried it on the driveway (concrete) but the handset just skidded along and wouldn't stay put for the car to climb up on top of it! I'll have to see if I can find a way to overcome that little obstacle.....

The grass is actually over sand and is darn near dead (no rain here of consequence in the last month or so) as you can see - there was basically no embedment or "support"....

__________________
"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

Padowan

Some nice tests there, but one question - It's good to know that the housings can stand up to an SUV driving over them and a cinder block being dropped on them - what are you doing with regarding testing the shock resistance of the internal electronic components?

Also I would think that a combination "impact whilst under pressure" test would be a good one, to simulate catching and whacking the handset on a wreck whilst at 300' (~100m)

__________________

Genesis

I've got the latest cut of the PCBs on their way. Shock tests will be done once I have everything proofed up first....

That one's pretty easy - toss a finished unit from a decent height onto a hard surface repeatedly and see if it still works

Underwater impacts are MUCH less severe simply due to the far lower velocities involved..... Worst case is probably a scootering diver who nails a bulkhead or something similar.....

__________________
"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

teomannaskali

You mentinonned filling the housings with oil. For the deep. I tried that once with some motors for an ROV. The problem with those is the difference in temperature.

If they heat they they tend to leak out the oil. And if they see cold they tend to form a slight vaccum which will SUCK in some water.

I would think that some hard silicone would be better. OR even clear epoxy type material.

Just my thoughts

Teoman

Genesis

Yep - differential expansion of LIQUID filled handsets can be a REAL problem. The pressures involved can be truly extreme.

Silicone won't do much for you. Filling with epoxy is an option but doing so is a "one way trip"

__________________
"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

Back online with my efforts in this regard... (took the summer off to travel with my kid.)

The last issue I had with a wierd "drift" in the pressure values going into the ADC. All looked ok on a DMM, but was obviously not. That pointed to high-frequency noise....

So.... getting tired of chasing my tail, I sucked it up and ordered up a TDS 1002 - so now I have a real DSO on my desk.

And in about 5 minutes, I found the problem. The Instrument Amp I am using has a real hard-on for capacitance on the output! I was bypassing the output into the ADC to prevent noise coupling, but apparently this instrument amp has major problems with that and was oscillating at ~80khz with a real nice amplitude.

Snip on the bypass cap and poof - problem gone.

Amazing how having the right tools on the bench turns what's a nasty problem into no problem.....

Back to the races..... I've got one more turn of the amplifier/ADC board to have run, then I think that part of it is all for the good and its on to the remaining mechanical issues.

__________________
"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

Good to see you're finally getting back to work.

While you've been goofing off and having fun,

I've been adding electronic O2 addition control to my Rebreather project. ..... This iteration of the HUD controller wasn't originally intended to control an O2 solenoid, but the basic capability was there, and I couldn't resist developing it.

I opted to use one of the ST Micro high side driver ICs for control of the new style Jaska solenoid, as used in the Megs. These ICs have better internal protective circuitry than you can make, on resistance in the low miliohm range, and logic level control. Here's a link to the thread where I gave some more details: http://www.rebreatherworld.com/rebre...-wanted-3.html


How's the handsets working out?



Darlene

Genesis

The VN750 looks interesting.... it wants 5.5V as a minimum input though - are you driving it from a 6V supply?

The Jaska solenoid isn't "commonly available" though - is it? Or is it?

The Status output on the VN750 gives you both short and open fault detection - not the same as an actual measurement of current draw, but still, useful.

Only one bummer - Mouser is limited to stock on hand (they're dropping it for some reason) - I think I'll have to grab some of these..... nice find Darlene!

__________________
"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

Digi-Key stocks them in several packages. 5 pin TO220 (pentawatt) and P2PAK are the easiest to work with.

The 5.5V is the guaranteed minimum, and typically they work a bit lower. I used an LD29150 (adjustable) regulator, and set it at 6.5V .... the LD29150 also has the inhibit pin on the PPAK, which I make use of.

The nice aspects of the Jaska solenoid are the .019" orifice, the molded coil, and stainless steel body. It can sit outside the loop, or even immersed, and be OK.



Darlene

jradomski

Are you going to use it along side of a constant bleed or by itself??
IF by itself make sure you have a reasonably high IP and have some long injections available.. (necessary for continuous ascents if you dont want to have to inject o2 manually to keep the po2 close).. The target to shoot for (after taking into account on/off times) is to be able to electronically inject about 12lpm (or better), the absolute minimum should be 6l at least thats what CE says (again after taking into account on/off imtes)...

__________________
Joe Radomski
CCR Trimix Instructor Trainer
ANDI Instructor Trainer Director #10

All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated.