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 Post subject: Tether cable
PostPosted: Jul 19th, 2016, 1:49 pm 
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Joined: Jun 19th, 2016, 12:03 pm
Posts: 10
Hi all, newbie here so hi and thanks for accepting me :-) just a quick one on the old tethers, has anyone ever used or even thought about using, scart cable???


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 Post subject: Re: Tether cable
PostPosted: Jul 19th, 2016, 7:30 pm 
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Joined: Feb 28th, 2013, 6:01 pm
Posts: 383
Location: Australia
Welcome Ozzyboy. No never considered SCART. Having the coaxial cables and signal wires could be useful but the cable with it's relatively large diameter would create too much drag. There are better control options available. Video baluns and cat5 cable will give video and 6 wires spare for control.


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 Post subject: Re: Tether cable
PostPosted: Jul 20th, 2016, 2:29 pm 
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Joined: Jun 19th, 2016, 12:03 pm
Posts: 10
Hi and thanks, yea I hear ya, but was thinking just cos it's 18 core individually screened and 10mm of, it might of been a decent option, and at £20 for 100m??


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 Post subject: Re: Tether cable
PostPosted: Jul 20th, 2016, 7:09 pm 
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Joined: Feb 28th, 2013, 6:01 pm
Posts: 383
Location: Australia
Haha. I nearly added "I guess this is surplus cable, cheap?". Dunno how good the picture would be given losses over a length of thin coax. Maybe you can source some cheap CCTV cable with decent coax and some control wires in the same jacket?


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 Post subject: Re: Tether cable
PostPosted: Jul 22nd, 2016, 12:37 pm 
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Joined: Jun 19th, 2016, 12:03 pm
Posts: 10
Ha ha ya might be right :D am going to stick with the cat5 and go from there, my first project so will learn from you old sweats(no offence intended lol)


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 Post subject: Re: Tether cable
PostPosted: Jul 22nd, 2016, 4:01 pm 
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Joined: Jun 19th, 2016, 12:03 pm
Posts: 10
You have obviously experimented and tried things, do you know if electronic components in a housing, specifically a relay board, work when potted with wax or oil?


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 Post subject: Re: Tether cable
PostPosted: Jul 22nd, 2016, 6:09 pm 
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Joined: Feb 28th, 2013, 6:01 pm
Posts: 383
Location: Australia
Yes had success with brushless motors, and slip rings (signal level - low current) in oil. I do not know how well relay contacts would go in oil. Personally I would not try it, but I can see you are wanting to stay with what is familiar, rather than use transistors etc. The wax could be the go provided you can keep it out of the relay housings, and use bare solid core wire through the wax. Insulation or stranded wires form a conduit for the water to travel. If the relay coil current is being carried by the tether then there will be noise generated, possibly enough to upset the video, each time a control button is released. Easy enough to test on the bench with full length of cable. If a problem, there are ways to minimize the noise.


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 Post subject: Re: Tether cable
PostPosted: Jul 24th, 2016, 1:42 pm 
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Joined: Jun 19th, 2016, 12:03 pm
Posts: 10
Thanks for all your help and sorry for pickling your head so much!! Cat 5, stranded or solid core best? And yea relay control is what I know best, but transistors? Tell me more lol, also sorry in advance for future head pickling and question time, I'm afraid we are just at the tip of the iceberg stage lol, besides all this, what is it you do? And how did you get into this as a hobby? If you don't mind me asking?


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 Post subject: Re: Tether cable
PostPosted: Jul 25th, 2016, 7:09 pm 
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Joined: Feb 28th, 2013, 6:01 pm
Posts: 383
Location: Australia
Pleased to be of help. The forum has gone very quiet in recent months. There is a lot of information here from past postings, just a case of using the search tool and some time going through having a critical look at some of the discussions.

Regarding the cat5, if you cannot get stranded then solid would be OK in my opinion. The tether will need to be fed in and out carefully from an organised pile on the deck, or from from a reel which implies some sort of rotating coupling, be it slip-rings or wireless device.

The tethers that I have made have a transition from cat5 or coax to heavy solid copper wires. The transition is potted in epoxy, meaning no water can ingress, and can form an end-cap of the waterproof housing. This is cheap but time-consuming and fiddly. There are "waterproof" connectors available at a reasonable price (Buccaneer is one brand) though these are best fitted to something with a better jacket than cat5, and if the jacket gets leaks then water will get into the connectors. The next step up is really commercial grade connectors and cable that are a lot more expensive.

By saying "transistors" I was being very general. This could cover anything from simply replacing the relay function with a solid-state alternative or using a variable speed controller and the gear that is associated with that.

With your mechanical background, pressure-compensated oil-filled thrusters might be a good choice. Brushes do not like oil, so enter brushless motors, which require an electronic speed control (ESC). Model aircraft ESCs typically do not reverse the motor. A model car ESC is therefore required. To control the ESCs a particular signal is required. This signal comes out of the model's radio control receiver (usually not of use under water), or can be generated by a microcontroller such as Arduino, or can come from a cheap "servo tester". Another option is to send RC "buddy box" data down the tether and control the ESCs that way, replacing the radio link with wired link. These methods are discussed on the forum. Here, any of the above methods, including relay control, could use the same cat5 tether.

Thanks for asking. My work background is electronics. I wanted to be able to inspect a boat mooring remotely (an excuse for getting a new toy I guess) so bought a cheap IP camera and started playing with that.


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 Post subject: Re: Tether cable
PostPosted: Jul 31st, 2016, 3:00 pm 
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Joined: Jun 19th, 2016, 12:03 pm
Posts: 10
Hi sorry for late reply, was on night shift so not had the opportunity, thanks for your info, yea I am reading through the forums as I go, but being a very pernickety individual, I don't want to miss anything so am starting at beginning and reading each and every post on all topics!(even if it's not a topic I need, there are still things that pop up that can be utilised and help!) And I appreciate your help very much, and anything I can help you with I am more than happy to return the favour(s) lol, I am mechanical but hydraulic and pneumatic also, I have ended up with cat5 solid core as got 100m of it for free! I have a standard extension cable reel which I have put the cat5 on, I don't have slip rings or any kind of rotary connection, so have opted for a more basic option for now, that is a 8 pin din connector from cat5 to the side of extension reel and control cable plugs in to that, means disconnect to allow more tether out but that's ok for first build and testing out!?? My controls are two old school Atari joysticks yea just on off but using a relay board that's fine as they are on off also as you know, I have found a great way to epoxy spot lights in a housing without soldering onto the bulbs themselves allowing for bulb changes if needed! My I have used melted wax to seal most of my electrics but the last part I'm worried about is the relays, a PCB with 8 12v 10amp relays on for the control, is how to seal them? Would melted wax damage them in any way?


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