If you were to design the perfect bottom timer...

[temet vince]

Hi all. I'm in a hardware class and am trying to design a bottom timer for tech diving.
I was wondering, if you were able to have the perfect bottom timer instantly appear before your eyes, what features/functions would you want?

The goal is to keep it bare bones and simple, which makes it easier to be: 1. Power efficient 2. Reliable 3. Cheap. (Way below $100). This is *not* going to be a dive computer!



Some example questions I have, but by no means should this limit your discussion:
1. Total amount of time it should keep (Uwatec displayed almost 1000 hours. That's just a waste of hardware. Realistically, how long do you all need before you'd reset it? 12 hours? Jw)
2. How deep should it go? Would it need to tell you how deep you are currently? Max you've been? Do you even want this information, or would you only want something that keeps track of time?
3. Would resetting it with a 3 second button hold work? Any easier/better way you'd like to reset it?
4. Should it reset between dives, or keep a running bottom time total for multiple dives until you reset it?
5. I was thinking it could be activated by a pressure sensor, but at what depth would you like it to start keeping track? 1 meter? Deeper would be more reliable.

 

[jadairiii]

Old Uwatec bt with user replaceable battery. Done

 

[nimoh]

oled screen and desktop software where the end user can design their own layout and what information to display.

 

[Pozz]

would you only want something that keeps track of time?

i'm pretty sure thats called a clock

 

[eelnoraa]

Scubapro Tec2G gauge mode feature and a better display, preferable color.

oled screen and desktop software where the end user can design their own layout and what information to display.

Yes OLED is newer, but not without its drawback, compare to LED backlit LCD, OLED has lower max brightness, less power efficient, lower pixel density. OLED has better viewing angle compare to low end PN LCD, but higher end LCD is almost as good. OLED has higher contrast ration not because it is brighter, but because the black is blacker. Place a OLED screen and LCD screen under bright sun light, LCD will be much easier to read. Lower power consumption is also a big plus for dive computer.

 

[Dr. Lecter]

if you were able to have the perfect bottom timer instantly appear before your eyes, what features/functions would you want?

The goal is to keep it bare bones and simple, which makes it easier to be: 1. Power efficient 2. Reliable 3. Cheap. (Way below $100).

Your question and your goal don't really match up. Are you asking about an ideal BT, or are you asking about what's essential so you can make a cheap puck that'll do the job satisfactorily?

---------- Post added July 3rd, 2014 at 01:46 PM ----------

1. Total amount of time it should keep (Uwatec displayed almost 1000 hours. That's just a waste of hardware. Realistically, how long do you all need before you'd reset it? 12 hours?

Somewhere in the 200 hour range should be sufficient. A lot of us know people who have done dives pushing 12 hours; some here have probably exceeded that number themselves. But maybe there are people doing exploration diving with deco habitats that are under for more than a week? I dunno.

2. How deep should it go? Would it need to tell you how deep you are currently? Max you've been? Do you even want this information, or would you only want something that keeps track of time?

Last question first: you're not a diver, are you? The whole point of it is as a means of seeing both depth and time...otherwise you just wear a dive watch and carry a depth gauge. As for depth, CCR dives in the 200M range are becoming increasingly common, and dives around 100M are pretty normal for a substantial number of divers. I think the OC record is somewhere in the 300-400M range.

3. Would resetting it with a 3 second button hold work? Any easier/better way you'd like to reset it?

Maybe I'd prefer it to be harder to reset a key source of information.

 

[lowviz]

Hi all. I'm in a hardware class and am trying to design a bottom timer for tech diving.

Excellent! Needed re-doing for years now.

what features/functions would you want?

Only what is needed. BIG display showing current depth on left and dive time on right. Able to be read by someone with 20/20 vision in good light at 1 foot underwater WITH NO MASK. Somewhat smaller across entire bottom "Max Depth = XXX"

The goal is to keep it bare bones and simple, which makes it easier to be: 1. Power efficient 2. Reliable 3. Cheap. (Way below $100). This is *not* going to be a dive computer!

1) Liquid crystal display, not backlit, anything else will kill you on power consumption.

2,3) No buttons, one set of permanent contacts to exterior -water activated, third contact to scroll through the three values on last 8 dives. Wet fingers and touch common contact and either of the other two depending on what you want to see. (turn on & show last dive or scroll through past 8 dives)

1. Total amount of time it should keep (Uwatec displayed almost 1000 hours. That's just a waste of hardware. Realistically, how long do you all need before you'd reset it? 12 hours?

Memory costs nothing, datalog every three seconds upon water activation. If pressure exceeds 3m/6' go back and keep the early stuff, if not, it was just somebody looking at the display on the surface. 3 second datalogging gives you good ascent and descent detail.

Don't reset anything, start overwriting after 8 dives.

2. How deep should it go?

330 meters

Would it need to tell you how deep you are currently? Max you've been? Do you even want this information, or would you only want something that keeps track of time?

Absolutely current depth and dive time always visible during the dive. Max depth required for certain types of on-the-fly deco planning.

3. Would resetting it with a 3 second button hold work?

No buttons! You are building a submarine. The fewer hull penetrations, the better.

Any easier/better way you'd like to reset it?

IRDA link that uploads all dives in simple format (that can be read by Excel) then asks if dives should be erased or left alone.

4. Should it reset between dives, or keep a running bottom time total for multiple dives until you reset it?

Overwrites after eighth dive. Do not keep a running total of anything. Eight individual dives.

5. I was thinking it could be activated by a pressure sensor, but at what depth would you like it to start keeping track? 1 meter? Deeper would be more reliable.

Water activated, keep the initial data unless 1 or 2 meters is not exceeded, then toss it. If 1 or two meters is exceeded go back and start from the splash data.

Inductive coil in the base for recharging the ultra-reliable battery, capacitor. Sealed battery, will last for many years with ability to recharge.

 

[100days-a-year]

200+Hrs @ 10sec intervals
Wireless download and a format interfaceable with deco software if possible
Depth,Time,Temp in large font
cost much less than a cheap computer with guage mode
puck shape for flexible mount options

 

[temet vince]

This was in response to Dr. Lecter. You guys/girls posted so fast it was already outdated before I posted it!



You're right, the question probably sounded at odds with itself. It was mostly a way to get discussion going. It's nice to see what people want, even if it can't be included in the specs. Like nimoh wanting a bottom timer where the user could customize the display screen. There's no way I could implement that in a sub $100 unit, but I'd never even thought about it before. That's an amazing idea! In the end, I'm basically wanting to see what people would need out of a bottom timer that's not over-designed, but I also am just curious as to what people could come up with even if I can't use it. It's neat.

Like the 200 hour range thing you mentioned. Is there any reason to keep track of 200 hours of dives on a bottom timer? When someone gets done on a 12 hour dive, they're not usually going to be going straight back down and diving again, are they?

I've dived a little. I use a computer, but I also know the tech community likes things different ways. If someone wanted a "bottom timer" that is basically just a cheap dive watch (without actually telling the time), then I wanted to know about it.

I think there's a difference between cheap in price and cheap in build construction. By figuring out what people value in bottom timers, it may be possible to not over-engineer these suckers and get the price down while not skimping on build quality. And maybe it's not possible. It's just a fun thing to think about and try to play with. I definitely appreciate your input.

 

[Dr. Lecter]

I like almost everything in lowviz's post, especially the lack of buttons and the induction charging. I don't think data logging for this kind of thing is worth the cost/complication of IRDA or bluetooth or even a port, but maybe I'm overestimating the cost/complication. I'd probably rather know my average depth rather than my max depth, if I had to pick, but seeing both would be ideal.

So, on constant display I'd have

1) TOP LEFT SIDE: DEPTH TOP RIGHT SIDE: TIME (HHH:MM:SS) Both values just huge/clear as mentioned.

2) Middle: Start/stop timer HH:MM:SS (default 00:00:00, touch two-contact combo to start running, touch again to pause/restart, touch and hold 5 second reset).

3) Bottom left side: Max depth Bottom right side: Avg depth