boatman

Yes, a non-polarised capacitor between the existing system and the mystery box will prevent the DC calling signal to the new handset from going back down the line to the existing beltpacks. It needs to been a minimum of 1uF/50V but anything larger will be fine. As the new box is DC isolated from the rest of the system you might need the LED indicator which will only light up when called from the new handset. If you don't need that then it's only four resistors, two capacitors and a PNP transistor and should only take half an hour to build on a bit of stripboard. If it helps I have all the necessary components and could knock something up for you to try.

It's not just a short of the power rail to the bus, a little bit more sophisticated than that. The attached picture is the call button section of Bluecom. I think you might get away with just building that section and isolating it from the bus with a 1uF capacitor so that the call voltage doesn't feed back to the rest of the comms system. I can't guarantee that it will work but it shouldn't do any damage!

The MX802A used an 18v-0-18v AC supply. Something like this should do the trick: https://www.ebay.co.uk/itm/144754499033 You should check the pinout of the supply against the input PCB in the mixer to sure that the magic smoke doesn't escape.

20 litre plastic containers (ex-cleaning companies) filled with water? Oh, and they're free!

Well done @Crazy Al it's over 11 years since the design was started and well past the time it was migrated to SM components. Good luck with the migration and if there's anything I can do to help send me a PM. Although I no longer have access to EasyPC which was the original design platform, I do have Kicad.

Wood should be OK, but I think even galvanised tube will suffer end damage on concrete. A lot less than aluminium but the underlying steel isn't hardened.

One thing to be careful of when storing ali tube vertically is end damage. If the floor is concrete put down some padding (6mm rubber sheet is ideal) otherwise the tube ends will suffer.

So, an M16 connecting nut would be a good place to start. I'll be in the Inverness Men's Shed on Tuesday and I'll see what we've got to hand.

Is this what you are looking for? I turned it many years ago from a chunk of hex bar. The hex end was drilled & tapped to M10 with a bit of studding screwed in (with Loctite). You can make the stud any size you want. If you have a Men's Shed in your locality, give them a call as it's something they should be happy to knock up for you (we do this sort of thing every week in our Shed).

Get in touch with Brian Summers, he's the most likely source of manuals etc. http://www.tvcameramuseum.org/

Sorry I missed this post. here's a link to the zip file for version 1.4.

In my last job before I retired we used something very similar to this: https://bownetcms.co.uk/shop/data-cabinets/19-wall-box-accessories/power-distribution-units-pdu/uk-13a-bs1363-socket-12-way-vertical-rack-mount-pdu/ Quite expensive but very robust. Oh, and it was nearly 20 years ago!

Oooh err, I still have a 2020/2021 trade catalogue. It's probably worth putting it on Fleabay! Seriously though, this is very similar to the box we used for Bluecom and will probably do the trick: https://cpc.farnell.com/multicomp/mcrecs80/case-aluminium-80x108-5x45mm/dp/EN85413

You might find that adding a couple of general purpose transistors improves the performance.

Yes, the PIC12F629 is still available. You could substitute it with the PIC12HV629 which has a built-in shunt regulator so the 5V regulator can be dumped.