WATERPROOF POTENTIOMETER QUESTION

[SVEN1]

Funny thing I was going to post about that in my last reply.
That's something I thought about a while back for my PI. I would just have to redo the PCB into a long version.
Had it all figured out and it would mount under the armrest. For the land unit I was going to use aluminum for a shield.
It would have had to be at least 12" long to fit everything and was going to be somewhat a pain to mount all the toggle switches and pots.
End caps would have to be machined with an o-ring groove for water units. I already figured out how to keep the end plates in place and snug..

If using plastic for a water unit, make sure it has some UV protection. You would want polycarbonate tubing. What held me back was the cost if you wanted 1/4" thickness and 2 1/2" + outside dia. size.
You can use some PVC tubing with end cap fittings like they have for water filters. Take a file and file in the flats for the pots. Another idea was buying a water filter housing and cover. Couldn't find the right size
at a reasonable cost. Now if you know someone in the water filter business, they may have some used stuff on hand cheap.

[daverave]

a long version mirage would be really good !!! i think machined end caps would present a big problem for someone like me to get done....so not sure how to get around that one....it seems a lot of work to get a detector housing 100% waterproof.

[woodbob123]

Glands have arrived good news is that it's quite easy to machine them down fit a small sleeve and "O"ring now when I tighten down the top nut that normally squeezes the rubber seal and locking "fingers" together it squeezes down on the "O" ring. will try and get a photo in the next day or so.
Tube is 40mm inside dia thick walled PVC marked up as high pressure can fit 4 glands on end cap but now need to sort out pots, could make and bond a saddle to tube but that will cause other problems such as access.
Plan is that pots and end cap will be as one unit what may be a problem is size of fingers as knobs are small and close together.

Now if we can reduce no of pots it will make it much easier ideal would be to have 2 cables exiting bottom one to coil other to headphones and battery pack could then have on/off and volume with batteries with just single control on top cap that would be simple. housing would then be fine for diving?? any thoughts on type / size of batteries

hope you can see what I mean but until I get a bit further its hard to describe what does not exist but coming along fine these are the problems I like and enjoy. Bob

[daverave]

all sounds interesting and will be nice to see your pics once you have things sorted...are you having batteries in the same tube or separate ???

[daverave]

Hi Sven
i saw some hex glands on the internet...what size do i need to order for standard size pots and toggle switches ??? for now ive decided to go with the ultra box 206 as it will be suitable for what i want to do.

[SVEN1]

You'll have to read the data sheets to determine the thread size on the pot , toggle switch. Then buy accordingly.

[daverave]

for now ive decided to make the detector shower proof and to be able to put the detector down on the wet sand surf...would i still need those special pots that you mentioned or can i just use normal pots ???

[SVEN1]

You can use cheap common pots, you'll still need to add the seals. If your pot shafts are not stainless or chrome plated brass. The salt water where ever it touches will start to corrode the shafts really fast.
Make sure you rinse the entire unit off with freshwater after each hunt. Most hinge pins even if stainless on many of those water proof boxes will rust if used in salt water enviroments.

[daverave]

Hi Sven
ok i will look for some stainless steel or chrome plated brass pots...i guess plastic would be another type ???

[daverave]

Hi Sven
Ive just ordered ultra box 206 and i wanted to ask you if you could recommend a waterproof coil plug and socket...ive been on ebay looking for the pots but most are cheap aluminium type so guess i will have to look else where for these pots.

[SVEN1]

I don't care for the plastic shaft pots, the longer shafts flex a bit more than I would like. You can use them. But, some are as expensive as the precision pots.

A good reference site on pots http://www.potentiometers.com/index.cfm

[woodbob123]

Have made a couple of ideas using parts I have in stock, one is much too complex to make with small s/s shaft and coupler but the "O" ring seal seems to work well black gland was simply machined back and drilled out to suit o ring. Second one is much simpler pot screws into spacer, gland also screws in plus some solvent to bond and seal it, pot shaft has to be smooth but splines could be sanded down and the rubber seal supplied would be ample for non immersion, could be fitted with o rind one or more and a packing sleeve would then reduce height. Will be ordering some more glands to make up a final version.

[daverave]

Hi Bob
Thanks for the photos....ive decided to make a dectector that can be put onto wet sand surf and weather proof...ive ordered a box and a 6mm slotted pot and some control knobs and will do some experimenting before ordering more....i found some hex seals on the internet but need to get the correct size...all these things have been very vague to me as never done this before.

[SVEN1]

Easiest and safest way is still using the hex seals.

Just drill the pot mounting holes in the case. Put some sealant adhesive on the base of the pot. Slide pot into hole, screw on hex seal. Attach knob and your done.

If you want to get more critical. tap the holes for the pot threads, apply sealant to pot base and some on the threads before screwing pots into place. You won't have to worry about leaks.

Below are pictures of an earlier box

[daverave]

can i use epoxy resin or silicon on the base of the hole to seal ??? what sort of tool would i need to tap the holes ??? did you use splined control knobs or different type ??? sorry so many questions but trying to get everything right with no problems.