BlueClone - The Blue Room's Own Comms System

[Brian]

You could send DTMF (telephone dialling tones) over the audio channel quite easily. There are 16 distinct tone-pairs so you theoretically drive 16 different tally channels.

 

The MV/MT8870 is a useful decoder.

[timsabre]

You could send DTMF (telephone dialling tones) over the audio channel quite easily. There are 16 distinct tone-pairs so you theoretically drive 16 different tally channels.

The MV/MT8870 is a useful decoder.

 

I really don't think it's worth the complexity, just buy some starquad cable and use 5 pin connectors, and have a splitter box at the vision mixer. That gives you 2 colour tally easily.

On a camera rig all cabling is a home run anyway so there's no advantage in making it work on the comms loop system.

[Hieronymus]

You could send DTMF (telephone dialling tones) over the audio channel quite easily. There are 16 distinct tone-pairs so you theoretically drive 16 different tally channels.

The MV/MT8870 is a useful decoder.

It doesn't sounds as fancy as Dans' idea, but worth investigating.

 

 

On a camera rig all cabling is a home run anyway so there's no advantage in making it work on the comms loop system.

I don't see the homerun. We film at different venues at have very limited time to set up. Being able to use cables that are easily available, replaceble or extendable (like normal 3 pin XLR cable for the comms and 50Ohm COAX for the SDI signal) is a must have feature in my mind. You can borrow 3pin XLR from any light (DMX) or sound (mic, speaker) guy. Also not breaking the daisychain helps in this. Sometimes I want to be able to move the camera spots and thus need even more cable. (so the cameraman easily unplug and plugin at the new location).

 

I agree that it looks like a complex system too just switch a bunch of LEDs, but I like it because it doesn't alter any of the comms system properties. (I might also like it because it sounds like a cool project. After reading all this I gave up on the idea to fix the ComClone myself ;-), so I need something else to geek on)

 

It is good to know you have many ideas how to add tally to the intercom.

[pmiller056]

Why don't you use CTCSS (aka 'tone squelch') tones for the tally signals? Further information at http://en.wikipedia.org/wiki/CTCSS

 

It would be easy to add this signal to the bus and for each receiver to detect their pre-set frequency and put a light on. Good selection

of boards, modules and chips to do this are available.... Don't use near multiples of 50Hz (or 60Hz if relevant to you) because the

system will be too easily fooled by mains interference.

 

Peter

Edited October 4, 2013 by pmiller056

[bruce]

I don't have access to a Tecpro or Stonewood base station/power supply,

 

John - I've got a tecpro PS711 power supply sitting in the garage - you can borrow it if you want.

 

(yes, I know there are plenty around, but I'm probably closest to John's island hideaway...)

 

There's also some tecpro beltpacks, one with some BBC mods, and a LS411 loudspeaker station - let me know if they're of any use to you.

[Hieronymus]

VOLUNTEERS WANTED

 

Anyone interested in helping John and I get this finished?

 

What would be great would be some volunteers to take the parts list and each add one column to it containing a specific supplier's part numbers.

 

I'll post an excel spreadsheet here later tomorrow and if a few people could spend a couple of hours going through it and adding part numbers for the following suppliers it would be greatly appreciated.

 

Brian, did you post that spreadsheet? Or did I missed it? Love to help.

Edited October 4, 2013 by Hieronymus

[boatman]

I don't have access to a Tecpro or Stonewood base station/power supply,

 

John - I've got a tecpro PS711 power supply sitting in the garage - you can borrow it if you want.

 

(yes, I know there are plenty around, but I'm probably closest to John's island hideaway...)

 

There's also some tecpro beltpacks, one with some BBC mods, and a LS411 loudspeaker station - let me know if they're of any use to you.

 

Thanks for the offer but we made the decision to go with one male & one female for each circuit. A quick recap of the current spec:

 

The Bluecom Power Unit will support two independent intercom rings and have the facility to common them. The unit will be designed to fit into the same enclosure as the beltpack There will be a male and female 3-pin XLR for each circuit. the connectors for circuit 1 will be on the front panel and those for circuit two will be on the back panel. The power will come from an external wall-wart 24VDC supply thus avoiding any need for certification of an internal power supply. The DC input connector will be fitted on the back panel and will accept external supplies with either a 2.1mm or 2.5mm connector with positive on the centre pin. There will be diode protection should a supply with a negative centre pin be connected. There will be a power indicator LED on the front panel. The circuits will be commoned by a latching push-button and there will be a second LED to indicate when the circuits are commoned.

 

Link to schematic

Edited October 4, 2013 by boatman

[boatman]

There is a slight modification to the Power Unit schematic. The two rings now have separate reverse-polarity protection diodes as the chosen device can only handle 3A and the total load for two fully loaded rings may exceed that.

 

Schematic here

 

Please note that there are also four mounting holes so that the board may be built into a desk easily. This was omitted from the earlier specification.

[Dmills]

I suggest a polyswitch in series with each ring power line, and a fairly butch cap across the power input, that way a shorted cable does not take the whole thing down.

 

Regards, Dan.

[boatman]

Sounds like good advice. This cap and this polyswitch seem to be ideal.

[boatman]

Actually that capacitor is too big so I've used this one instead. There's one for each ring so it should be sufficient.

 

Revised schematic is here.

[Dmills]

Also a bridge rectifier right on the input so you can power the thing with pretty much any wall wart that comes to hand, it means that polarity becomes irelevant, and that even an AC supply would work.

[Brian]

...pretty much any wall wart that comes to hand...

With the caveat that, because there is no regulation in our base station, if you end up with more than around 28v DC you run the risk of toasting your beltpacks.

[boatman]

Also a bridge rectifier right on the input so you can power the thing with pretty much any wall wart that comes to hand, it means that polarity becomes irelevant, and that even an AC supply would work.

 

Most regulated 24VDC wall-warts have a positive on the centre pin. The only variation being either 2.1mm or 2.5mm centre pins. I think catering for negative centre pins and AC wall-warts is a step too far.

[boatman]

... and here is the component placement for the Power Unit at 2x scale.

 

Link

 

The big capacitors (C3 & C4) are 31.5mm tall and there is 33mm clearance between the top of the board and the case, so there should be no problem.