DIY Wired Communication for Umbilical

[Dwmathews88]

I am a commercial diver. I dive a Kirby Morgan SL 27 daily and a OTS Guardian both with Communications we run two wire with our umbilical carrying our surface supplied air. For all of you with some electrical background, how do I build a home made comms box... I’m guessing it’s like a 9 or 12 volt wired intercom. Speaker doublers as a microphone...I’m just not sure what I need, such as amplifiers, resistors, or anything like that. Any help would be appreciated.

 

[tbone1004]

Most run 4-wire, which isolates the speaker from the mic but if you're running 2-wire then it's the same wire.

After that it is just standard 12vdc radio components, same as you would find in any intercom type setup. Hell some commercial ones will probably work with little more than a banana plug conversion.

DIYing from total scratch is probably not worth the effort though without significant background in electronics.

 

[dm9876]

Electronics wise it's pretty simple but as tbone said, without experience maybe its not for you. However you might find some good step by step directions in some of the old hobby electronics magazines. Search the archives of Silicon Chip magazine for example and I see there are several projects that are probably close to what you want.

Search Articles - Silicon Chip Online

www.siliconchip.com.au

 

[dm9876]

Example of circuit complexity for 2 wire with ptt switches (do your usual ones have ptt or voice activated?)

https://4.bp.blogspot.com/-luuN32ILSdg/VBoUr-LLbzI/AAAAAAAAAi8/PdXZB45vZRQ/s1600/Two%2Bwire%2Bintercom%2Belectronic%2Bcircuit.jpg

 

[bakodiver391]

I actually built my own with some cheap IC board amps from Dealxtreme. It was a bit of messing around, but I am only semi-literate with electronics. I ended up using one amplifier board as a pre-amp for the main amp, with capacitors in between( very important). Also used a double-throw, triple pole switch for switching between talk and listen. It works OK, cost less than $50 as opposed to 1K plus for a commercial model but of course is not certified for use anywhere in the first world. I built an integral lithium battery pack with some 18650 batteries I got from an electric outboard motor, which works very well and gives several days of duration.
I use a hand held microphone and earphones for the tender as the dive boat tends to have a lot of ambient noise. The earphone jack should be the type that interrupts the signal to the speaker when headphones are plugged in (very commonly available at Radio Shack etc).

 

[happy-diver]

https://www.deepseaclassifieds.com/pro-diving-equipment/pro-drae-set-andre-m.html

 

[Dwmathews88]

Example of circuit complexity for 2 wire with ptt switches (do your usual ones have ptt or voice activated?)

https://4.bp.blogspot.com/-luuN32ILSdg/VBoUr-LLbzI/AAAAAAAAAi8/PdXZB45vZRQ/s1600/Two%2Bwire%2Bintercom%2Belectronic%2Bcircuit.jpg

On the diver end they are not PTT. Mic is always on. Surface is PTT

 

[dm9876]

On the diver end they are not PTT. Mic is always on. Surface is PTT

Doorphone Intercom Circuit

Discover all about 1001+ electronics circuit, schematic, PCB Layout you can find here, its very large database of an electric circuit.

www.elcircuit.com

Here is an alternative with one ptt switch and could be done as two wire with all the electronics at the surface however I think it's probably too simple to work well as the transmission line (the umbilical) is in the output side of the amp on when transmit but in the input side of the amp when receiving. But it may be worth some testing and adaptation with seperate circuit for each direction (so you can set different gain in each direction). Then have multi-pole switch to change over between the circuits.

Seems like the use case is unique enough that an existing working published design might be hard to come by and it would take some development work. So not as simple as I first suggested.

Dean

 

[dm9876]

Ok what I suggested with multi-pole switch and two circuits is what bakodiver391 already described but maybe (?) with seperate mic and speaker (3 or for wire)

 

[Dwmathews88]

Doorphone Intercom Circuit

Discover all about 1001+ electronics circuit, schematic, PCB Layout you can find here, its very large database of an electric circuit.

www.elcircuit.com

Here is an alternative with one ptt switch and could be done as two wire with all the electronics at the surface however I think it's probably too simple to work well as the transmission line (the umbilical) is in the output side of the amp on when transmit but in the input side of the amp when receiving. But it may be worth some testing and adaptation with seperate circuit for each direction (so you can set different gain in each direction). Then have multi-pole switch to change over between the circuits.

Seems like the use case is unique enough that an existing working published design might be hard to come by and it would take some development work. So not as simple as I first suggested.

Dean

So this is correct there is a gain for tender volume and a gain for diver volume.