Creating a dive computer with Location and Communications

[Manjula Ellepola]

Caveeagle I re-read your post...very good insights to consider. Thank you
At this point we have kept away from any diver computer functions as we want to focus on our core functionality. However you points are noted for the future.

 

[Manjula Ellepola]

We are looking at buttons for our device. We don't like the push button type due to the potential for failure. This leaves magnetic and sensor types. Magentic sounds attractive but will disturb the compass. The sensor alternative is piezo but I have seen some vids on youtube where you have to tap very hard. Further challenging the design are heavy gloved hands.

I would like to hear from your collective experience and suggestions on this subject. Thank you

 

[RayfromTX]

I would prefer push buttons but pay attention to the ability of pressure to push and hold the button down below certain depths.

 

[KeithG]

We are looking at buttons for our device. We don't like the push button type due to the potential for failure. This leaves magnetic and sensor types. Magentic sounds attractive but will disturb the compass. The sensor alternative is piezo but I have seen some vids on youtube where you have to tap very hard. Further challenging the design are heavy gloved hands.

I would like to hear from your collective experience and suggestions on this subject. Thank you

How many buttons do you need? If you check out the Uwatec Aladin Ultra you will see a very simple design of 4 "wet contacts". It also has a "pressure button". If you squeeze the computer the backlight turns on. No moving parts, no issues with pressure or water proofing.

 

[RonR]

Magnets don't disturb the compass if they are essentially stationary, as buttons are, they will calibrate out. We use magnetic reed switches and have a compass. Not needing a hole through the case is a big advantage. Wanting to access the buttons underwater for any kind of user interface would rule out wet contacts.

 

[Manjula Ellepola]

Hi Ron, that is interesting. We did some experiments here and the permanent magnets do influence the compass as they are much stronger than the earth field. However you are right they can be calibrated out. Reading the data sheets there is a caution saying that the soft ferrite sensor inside the chip could get damaged due to strong magnets. Early on in the piece we wanted to have low profile magnetic switches that slide. However we noted that the slide action does affect the compass. I guess a vertical motion would affect it less. I am sure you have lots more experience than us using magnetic switches. As it is a comms/nav device there is fair amount of interaction with it more than a dive computer therefore the buttons are a critical feature we need to get right. Challenging for sure

 

[DepthCharge]

I have piezo's in both my HammerHead controller and Shearwater computer. Neither one requires "HARD" tapping, just a gentle squeeze. Are you thinking about the switches used in the Liquidvisions? Those were accelerometers, and I agree, the ones I saw did need a good knock.
Later,
John

 

[BRT]

we would target the price from USD1,000 may be up to USD1,500 depending on the uptake. It could go sub USD1,000 if really popular..
My real question is would you find such a device useful? Would it make your diving a better experience?

Yes. Navigation and communications would be great but navigation and direction to other users would be fantastic.

 

[RonR]

Hi Ron, that is interesting. We did some experiments here and the permanent magnets do influence the compass as they are much stronger than the earth field. However you are right they can be calibrated out. Reading the data sheets there is a caution saying that the soft ferrite sensor inside the chip could get damaged due to strong magnets. Early on in the piece we wanted to have low profile magnetic switches that slide. However we noted that the slide action does affect the compass. I guess a vertical motion would affect it less. I am sure you have lots more experience than us using magnetic switches. As it is a comms/nav device there is fair amount of interaction with it more than a dive computer therefore the buttons are a critical feature we need to get right. Challenging for sure

Yes, strong magnetic fields can indeed damage these chips. We had a user who had consistent compass failures, they traced back to his storing his dive gear in the trunk of his car next to a huge bass speaker. But the tiny neodymium magnets used in the buttons don’t have any effect on the compass chip if they are kept at a reasonable distance. You are correct in that motion in alignment with the magnetic axis creates very little disturbance.

 

[Manjula Ellepola]

Yes. Navigation and communications would be great but navigation and direction to other users would be fantastic.

Hi BRT yes indeed we will have Navigation and comms to other users. They are the core features of the device