Back On My Horse Again ...... HUD Controller, the Next Generation

Scuba_Vixen

Hi Guys,
I've climbed back up on my horse and I'm having another go at it.

Actually, it was a bit of a blessing in disguise, (the delrin porosity issue) as I've taken the need to do some redesigning and made some worthwhile improvements.

Notably, the 3 lcd digital display will be much smaller and more streamlined, and in its own remote housing that will clip off to the right chest D ring. It should no longer require a battery in the housing.

In the 'Next Gen" unit,
The HUD controller module and battery pack will be housed in a custom sized Sartek acrylic can-light canister. The module will actually just fit in the smaller standard size acrylic canister, but Carl's adding a second piston O ring to the lid and making it 1" longer for me.

The canister will mount nicely where the original Drager tank mounted at the bottom rear of the shell. I have an extra G-Snaps that should be handy for that. The 2X16 LCD on the controller module really only has to be visible for pre dive calibration, so relocating it here is no problem.

There will be a third cable now, to the new smaller 3 lcd PO2 display I mentioned already, as well as the original 2 cables to the cells and HUD.

Battery changes or recharges will be by popping the latches on the canister to get to the battery pack, just like you'd do with a can light.

I opted for using 9.6V, 1600 mAh, NiMH battery packs with 8 AA sized cells. They are available for RC cars etc, so they are readily available off the shelf at Radio Shack. ... "Easy to get" is an important consideration down here.

The bigger battery pack will last soooo much (almost 12 times) longer than the 9V batteries in the original design, a much needed design upgrade.

With the new battery pack, I did away with seperate batteries for the HUD and the 3 lcd digital PO2 display. With that much capacity, it just isn't needed. I did keep the individual magnetic reed switches for each module though.

To make it all work, the 3 lcd module has to be redesigned to use the 5V supply Datel voltmeter modules, as compared to the 9V battery supply modules used originally. (the original design is about the same as the Mark Monroe PO2 meter circuit)

By using the 5V supply modules, the power can come from the canister, and share a conductor in the cable with the common negative wire for the cell inputs. ... With the 9V modules, by their design, the negative analog (cell) input can't be referenced to the supply negative, but it can with the 5V supply modules.

That would mean 3 conductors, 1 for each cell + and 1 condutor for common cell - and 5V power - and 1 conductor for 5V power + ..... Total of 5

The reason that's important, is that 2 to 5 conductor cable and connector sets are fairly standard, (6 or more is Not) and I have a perfect size, 5 conductor one left from something it wasn't right for.

I already built another 5V regulator board and potted it into the main HUD controller module, after making a couple other mods on it to make it more "canister shape and size" friendly.


Here's the changes to the controller module for the "Next Gen" configuration:

1) Added another 5V regulator for the planned new display module

2) Took out the original reed switch for the HUD controller and replaced it with a much heavier duty one (it got to where it wouldn't turn off), which required physically relocating it on the module

3) Put a new reed switch for the display module in the same new location, so that a single magnet turned off both modules

4) Cut off a small section of the controller module where the reed switches and battery wires originally were to make it fit in a canister nicely and redid the battery wire connection points

5) Changed the "power-in" wiring to accomodate the new switch location, 5V display module regulator, and battery pack



I was going to wait to post how I was recovering from my "leaky housing setback" untill the canister gets here, and I've made the new 3 lcd display module. ... (about another week or so for both) ..... But I'm too excited already to not share it with you.

Here's a pic of the modded controller module with its new battery pack, ready for it's new canister with room to spare. The other pic is the way it was originally for comparison.

The relocated reed switches are in the epoxy block above the LCD display and the new 5V regulator is in the new epoxy block at the lower right. The blue wire is the 5V supply to the remote PO2 display.



Wish me luck,

Darlene

kevin stone

Looks COOL!!!!!!!!!!!
glad to see that your back at it
keep up the good work

jknights

Well done Darlene.
Pushing back the frontiers!

Looks like a nice improvement.
Every cloud has a silver lining.

Scuba_Vixen

I came home from work to an email from Carl, and my new canister is ready to ship out tomorrow. WOOOOOOO HOOOOO ..... What incredible service!

One thing I'm also going to try out in this redesign, is to not only have the 3 lcd PO2 display powered from the battery pack in the main canister, but driven from an op amp board in the main canister, as opposed to running the millivolt signals from the cells to the canister and then also to the remote 3 lcd display.

That will allow using 2V range displays, so that I don't have to send low level (millivolt) signals within the power cable. It would also mean that anything that happens to the cable or display module doesn't effect the millivolt signal from the cells to the HUD controller in the canister.

It also means, a smaller, more compact display module, because I won't have to have cal pots in the display housing! Calibration is by fine adjustment to the amp gain pots on that board.

That way everything gets calibrated at once and then the canister latched closed.

Keeping my fingers crossed that I don't find any more "Gotchas".


Darlene

Genesis

Nice! Keep us posted!

__________________
"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