A Method for 100% Water Proof Control.

[chemelec]

Using Two BAR Magnetics, you can create a 100% Water proof control.
The magnets need to be Reasonably Strong, but this Does work very well.

The Pot with the attached magnet on the inside gets mounted so the magnet is Close to the case.
Likewise with the Magnet on the outside also close to the case or Magnetically Holding itself to the case.

Hope this is Useful to some of you.

[Koala]

Thanks for sharing. Seen magnet drive on electric ROVs not thought to use it on pots.

[WM6]

Thanks Gary. Are your inner magnet and Pot rigid clamped together or you use some sort of cardan joint?

[Waikiki_Sweep]

Good idea. I have tried it once but magnets were not strong enough. To work it needs really big and heavy magnets.

Anyway to control your waterproof device by magnets is a magnificent solution

It is popular way to build controls with using Hall Sensors. So you can keep sensor inside waterproof case and rotate magnet outside. Sensor will keep voltage proportional to magnetic field applied.
http://simhq.com/forum/ubbthreads.ph...ll_sensor.html

Also if you need to switch something inside waterproof case or press a button there is a Reed Switch devices available.

Two steel contacts connecting inside glass case if you bring magnet close to it. It is very sensitive and can be turned on by small magnet.

I am using Reed Switch to turn on LED light an night in my waterproof detector. Do not recommend it for high current. For example to turn on the detector because charge of tank capacitor will burn Reed Switch.

Also I have to tell if you remember that 12k pot from Florida Components with O-ring inside. It starts leaking after half year of use. I am still using it but replacing 2-3 times a year with new one. (I have purchased 18 pieces to spare)

[chemelec]

Waikiki Sweep, Good idea. I have tried it once but magnets were not strong enough. To work it needs really big and heavy magnets.

There are LOTS of Quite Small and Powerful Bar magnets now, that will Easily Penitrate 1/8 plastic and turn a Pot Shaft.
I have a few here that pull over 1.5 Inch distance.

I have previously used this method on a few pieces of Boat Equipment with Excellent success.
Unfortunately I don't have those pieces here to take pictures of them.

[Koala]

I was thinking of a few neodymium button magnets fixed to a plastic washer it's hard to pull two of them apart. Should work fine.

[chemelec]

I was thinking of a few neodymium button magnets fixed to a plastic washer it's hard to pull two of them apart. Should work fine.

Yes Meodymium isgreat and they are Powerful, but Button Magnets Don't work well.
They are N/S on Opposite SIDES.
Possibly Using 4 with each set of Two, Glued Opposite side by side.

Ideally you want either Bar or Horseshoe shapes. (N & S on same side at each end)
So N & S on one side, Attracts S & N on the Opposite Side of the plastic case.

[chemelec]

However, You can easily use Button Magnets on SLIDE Potentiometers.
Since they don't require a Turning motion, They are Just a Straight line Movement.

[golfnut]

You can get ring magnets - if you get the right inner Dia hole you could key it to pot shaft and have a ring magnet outside which is knob shaped already. http://proto-pic.co.uk/magnet-ring-3...FUTmwgodLTUAVw S

[Waikiki_Sweep]

If you will use rare earth magnets do not forget to seal in epoxy or so that one you will use outside because they corroding is salt water fast. If magnet is made from ferrite (looks black) there is no corrosion at all.
Also if you need magnet check eBay. 5,745 results for "rare earth magnet". Biggest magnet market in the world! Last time I have purchased on eBay four magnets for my scoops 120 Lbs. pooling force each for total $26 with free shipping.
Beer caps jumping into my scoop from 3 inches on air

[Thomas]

O rings work, if you know how to mod the opening for the shaft.

[Paul99]

Hope this is Useful to some of you.

Another method using readily available grommets and a long shaft that is lighter, more easily constructed, is easily fitted into a construction case, and is suitable for shallow depths....slap a bit of water pump or suitable grease/vaseline between the grommet and case and grommet and shaft... size the case hole to give an interference fit to the grommet to maintain pressure between the surfaces....

[barwildi]

Great ideas guys! I just noticed this interesting thread and had some thoughts of my own, if you can spare extra amp draw...

There are cheap, up/down digitally-controlled pots that have been available for awhile (web search) that could be implemented with Reed switches. Also, a simple flip/flop circuit triggered by a Reed switch could work for on/off operation as Waikiki-Sweep had mentioned. Then you would only need to carry a magnetic "stylus pen" to make control adjustments. Then the only items left requiring holes drilled would be for speaker/headphone jack and coil connector.

For future MD designs, I believe all of this may be more easily done with modern, cheap microcontrollers that have built-in digital-to-analog channels.

Cheers!

- Barry