WATERPROOF POTENTIOMETER QUESTION

[daverave]

I used these for my Bara, and going well. They are cheap, but they are not of poor quality (in Spanish are not synonymous) Look at the pictures that made Apberg:

[ATTACH]33427[/ATTACH]

Regards

is your barracuda waterproof detector

[SVEN1]

Cheap is right, they do not have a straight shaft which corrodes in salt water and will not properly seal with a Hexseal. They are not sealed from the outside the pot housing, will quickly fry when saltwater gets into them. And they don't have an o-ring at the bottom of the shaft.

Do it right get the right pots. Especially if your going to invest building a waterproof water hunting detector. Eliminate a bunch of problems right off the bat by not using a cheap common pot.
Yes, they cost a lot more than your common pot but, are worth it.

RV6 pots are small, they fit into smaller boxes if you have space limitations.

The Ultra boxes I use are rather small, cramped for space, you need think things out carefully, especially when it comes to battery placement. Also, note the boxes are plastic, no EMI shielding. I designed a special EMI
shield that works for my Mirage PI, of course I have a frequency control to dial out EMI that occurs. Now I do have a can of spray paint EMI coating which I haven't tried yet which is another alternative.
Coil size whatever you prefer. Think most guys will not use larger than a 11" or 12" coil, anything larger is harder to push in the water and harder to manipulate in the surf. If using a larger coil in the water, there's a good chance you will never be able to dig down deep fast enough to recover the target before it fills back in, depending upon the conditions. Larger coils are more prone to EMI. I don't have the option of saltwater hunting, so some one more experienced can help you in that regard. I use my PI in freshwater.

[woodbob123]

Dave how much space do you have in the box maybe able to make you some sealed glands with stainless rods and compressed ptfe seals very much as you would see on a steam engine piston rod, would be around 20 mm deep and 20mm dia out of pvc so could be bonded to box as well as a lock nut, if you think you may have space let me know and I can give it some more thought (will use you to check they seal ) I had thought of doing some work on the probe design in ITMD adding a coil as it does not require any controls just on/off switch If I make one will use it in the Med not the North sea LOL

[Fabian]

is your barracuda waterproof detector

Yes, but just only for splashing because I still don't finish the main seal of the box, but Apberg used those potentiometers in his Surf PI (long PCB).

Fabián

[daverave]

thanks Fabian for your reply to me...i will have to try and get some of these pots and seals.

[daverave]

Dave how much space do you have in the box maybe able to make you some sealed glands with stainless rods and compressed ptfe seals very much as you would see on a steam engine piston rod, would be around 20 mm deep and 20mm dia out of pvc so could be bonded to box as well as a lock nut, if you think you may have space let me know and I can give it some more thought (will use you to check they seal ) I had thought of doing some work on the probe design in ITMD adding a coil as it does not require any controls just on/off switch If I make one will use it in the Med not the North sea LOL

im still to purchase a box...im thinking of a ultra box if i can get everything in including batteries.

[SVEN1]

If you get the Ultrabox, just make sure you don't mount it to your handle set-up via the box lid. I feel the total weight of the finished unit would put too much stress on the lid. You want to mount the box portion to the handle set-up, so it supports all the weight. This way you know your playing it safe so it won't leak. Especially after you put all the work into building the water unit.
Just want to give you a heads up, warning you of some of the pitfalls in box mounting. If you could acquire a White's Surfmaster box and pots, with its strong lid and latching system you can mount from the lid.

I am always looking for a better waterproof box......short of having a custom one made....

I use the 206, very tight, took me about 40 hours figuring out how to make everything fit correctly and order of assembly. Make sure you check you battery size, PCB size etc and compare the inside of the 206 dimensions.
The 406 has tons of room a bit too much, I used one on one of my first builds.

Had another supplier of boxes, just can't find the link. They had some nicer sizes, they were considered waterproof, not submersible. Which translates you can drop the box into the water, it will float and keep the contents dry.
When submerged, water pressure is greater than air pressure, given a short amount of time depending upon depth it will leak water in. Watch the suppliers descriptions.

Please remember I am a perfectionist, so I go the extra mile to get everything just right the first time. Then I find a way to improve it the next time and this carries on. Hard to be satisfied.......always looking for a better way.

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A fellow water hunting, made a good post as a reminder to those that are long time water hunters or are new to water hunting. It is reposted here:


Sometimes the laws of physics are at play without us even being aware of them. For instance, if you take a plastic sealed container, put a small pin hole in it and submerge it hot water, you will notice shortly that air bubbles will start to leak out under pressure, simply because the inside temp is warming up, causing a positive pressure.
Now reverse the conditions. Warm the plastic container up, and place it in cold water. What happens? The cooling of the temperature caused a low pressure or vacuum to appear inside the container, and in order to reach an equilibrium, it sucked in water.
Watch how hot your equipment is before you submerge it in cold water. A metal detector in the car trunk or in the car with the sun shining on it will cause it to get extremely hot. By putting it in the cold water, you are causing a tremendous amount of vacuum to be 10

produced as the the inside of the coil, connector or electronics box tries to reach an equilibrium of pressure. Create enough vacuum in the coil, connector, splicing, electronics and you might get some leakage. Please......cool your equipment off before suddenly submerging it in cold water. This is true for all makes and models of detectors. Although leaks can occur for many other reasons, this should surely help.

[daverave]

your right its best not to mount the box using the lid...plus not good making more holes in the lid cause of waterproofing...the ultra box is the best ive seen so far compared to commercial detector waterproof boxes...i wonder if the ultra box seals are availiable as a separate spare part ???

[SVEN1]

Regarding the seals being sold separately. Never asked, I am sure you can get them. They are siliconed in place, I understand they don't need any silicone lube applied to them. I do it anyways.

One other thing, make sure the lid that comes on the box is clear, not colored. Makes it easy to see if you ever got any water inside.

Here's another tip, besides using a small pack of silica gel beads inside to box to absorb any moisture. Place a small piece of soak/swelling sponge in the bottom front edge of the box.
This is where the water will concentrate when in detecting position swinging the search coil. It will instantly soak up water. I came up with this idea to save the electronics. Best to mount the PCB as high off the box bottom as possible.
This is more important if using your detector in saltwater.

The swelling sponge is similar to that used for cleaning soldering iron tips. But, swell to a greater size.

Watch the video

http://www.viskoseschwamm.de/en/press.html

[daverave]

i wondered if it would be better to enclose the pcb into a smaller waterproof box and seal any wires coming out with silicon and wrap it with aluminium foil for screening then mount the smaller box inside the ultra box...this would save the pcb if any water should enter main box....only an idea ???

[SVEN1]

Still have to worry about air water temp changes causing any condensation within another sealed box.
In one of my versions I built a copper box to hold the PCB for shielding but, it was not sealed. Again a very very tight fit even when using the very small RV6 pots and providing clearance for coil, headphone connectors and wiring.
I have also lined the insides of the plastic box with copper foil tape with a layer of epoxy over it to seal it, after grounding wires were soldered to the copper on the lid and box and attached to the PCB.
You can eliminate the connectors by hardwiring the search coil and headphones using Heyco cable glands with strain reliefs like Fisher does with the CZ20, 21, 1280x. I have used this method in the past and used in-line waterproof connectors.

Here's some pictures

[daverave]

i see what you mean about the temperature changes of a smaller sealed box...im not sure whether to hard wire or use waterproof plug and socket for coil and headphones...how did you make those control box mountings as a very good idea instead of putting a bracket onto lid of control box...ive never made a waterproof detector before but will be a good challenge !!!

[SVEN1]

The silver ones pictured above on the yellow box was very time consuming. basically made a jig and laminated fiberglass cloth and epoxy over the jig in two parts. Once they were slipped into the box slots, they were laminated together on the bottom so they were joined into a 1 pc. mount. Then epoxy putty was used to form the curved pcs. for mounting onto a round shaft.

Current black ones ones that look like end blocks.I first made up a mock up out of balsa wood to fit exactly.
Sanded, sealed and spray painted them.
Then made a mold out of silicone since I had some kicking around.
Mixed up some epoxy, poured some in, added some fiber glass matt in multiple layers until the mold was topped off with epoxy.
Once cured, popped them out of the mold, did a final sanding. Drilled all the holes, Finished off spray painting them with Truck Bed Liner spray paint.

If your a machinist you can actually machine some nice ones out of Delrin plastic. Since I sold my machining equipment 15 years ago, I can still mold and cast.

http://www.treasurelinx.com/rg65_askook.html

Found these connectors to work, they are small, plastic and priced low......http://www.ebay.ca/itm/3Pcs-Waterpro...-/181371865181
This is a good ebay seller. So there is no reason to hardwire.

[daverave]

sounds like a lot of work to make them....maybe i will try and make some with abs plastic...i still have not bought a ultra box as yet...what do you think about the waterproof fishing float boxes ??? maybe suitable for putting detector down in the surf while digging ???? im a bit daunted with the thought of making a waterproof detector as a lot of work involved.

[woodbob123]

Dave do you need splashproof waterproof or as I offered earlier to work at 10mts ++ Been building some under water camera housings would be good if you test out some for me ha ha Bob