6-channel PCB demux (for Betapacks)

[IRW]

Hi All,

Having recently come into a small pile of betapacks (3 Beta-1's, and 4 Beta-2's), I find myself trying to work out how best to add DMX to the 6 that currently don't have DMX cards.

 

From what I can gather, the DMX cards were discontinued by Zero88 a fair old while ago, and in any case, I imagine the official ones would cost more than I am currently willing to spend on these packs!

 

I've come across this site, and I intend to contact the chap who runs it to see how easy it would be to modify his relatively economical 8-channel version to be more like the Betapack modules (with rotary switches instead of dips). I'm also currently talking to a colleague about creating something with an arduino chip, but was wondering if anyone knows of something off-the-shelf that doesn't break the bank? I do have a demux, but I'd like the option to use these packs in different configurations without having to hump that around as well!

 

Surely given the amount of analogue 6-channel packs out there, there must be something available?

 

Thanks,

 

Ian

[ocfe]

Anytronics make a DMX PCB for the Strand Act 6. Could this fit in a Betapack? Or maybe Anytronics could produce one for a Betapack. I'd have thought its worth a call.

[Geetrt]

Maybe the 72-channel botex/showtec/elation demuxer is an option? You would need only 1.

[Jivemaster]

I'd be very tempted by a global demux. DMX to 72 channels of 0 - 10v is a cheap box that lots of people sell for £199ish. Try Thomman or Terralec for a start..

 

You'd need the splitter cable, make it yourself if you can.

 

http://www.terralec.co.uk/dmx_lighting_controllers/showtec_multi_exchanger/17726_p.html

http://www.thomann.de/gb/botex_me72_multi_exchanger.htm

 

http://www.milinst.co.uk/# do lots of boards and bits but at £60 ish each you will be cheaper served by the 72 chan demux. Also a (any) commercial demux will be tradeable again later which odd PCB's may not be

 

Don't try swapping the PCB mounted components, 1/ there is the warranty issue and 2, you never get things that fit really well into the holes for something else..

[IRW]

Guys, please don't suggest full Demux units, I have one already, and am looking to modify the packs as described. I'm well aware of the need to fit the specific hole layout! (And before anyone says it, I'm more than capable of poking round inside these units safely)

 

I'm looking for suggestions of small pcb-based DMX-analogue options!!!!! (Preferably with rotary address selection, but I'm open to other options)

[smalljoshua]

Are those 72 way units a single 72 way card or multiple cascaded units internally? Could you cannibalize these if the latter proves to be the case?

 

Josh

[Stuart91]

Having done more than my fair share of mucking around with dimmers in the past, I can't help but feel that for the money and time you will spend to get the solution you want, it'd be better to just shift them them on and get packs with integral DMX.

[dbuckley]

Are those 72 way units a single 72 way card or multiple cascaded units internally?

 

One card.

[timsabre]

I did what you are trying to do as a homebrew board a few years ago... it is not very straightforward. You could do the 6x analogue out by pulse width modulating pins on an arduino (which didn't exist when I was trying) but then you wouldn't have enough pins to do the addressing, you'd have to do some sort of serial clocking thing. A biggish pic would probably have enough pins, maybe there's a picstart board you could marmalise.

[Jivemaster]

Look on ebay, there is a unit for spares or repairs for £50 the lot. You certainly will not get anything through CE marking for that price.

[pjb304]

I did what you are trying to do as a homebrew board a few years ago... it is not very straightforward. You could do the 6x analogue out by pulse width modulating pins on an arduino (which didn't exist when I was trying) but then you wouldn't have enough pins to do the addressing, you'd have to do some sort of serial clocking thing. A biggish pic would probably have enough pins, maybe there's a picstart board you could marmalise.

 

One the Arduino Uno maybe. But if you use the mega you'd easily have enough. It has 54 digital I/O channels of which 14 can be used for PWM.

[dbuckley]

If one is happy to use a carrier PCB with a module on top, a Teensy 2 or a Propellor Mini would both have mroe than enough PWMs, and are small, low cost, and can be built on a single sided carrier board. The question then becomes if the PWMs need to be buffered, but even if they do, its only six opamps, 3 duals, still in single sided board territory..

[IRW]

Hi All,

Thanks for all replies thus far- We're currently leaning towards an Arduino Uno chip, with rotary switches for address selection (and a couple of shift registers to give us a few extra inputs)- we've been studying some pre-existing modules that we've found online, and are fairly confident we can put together something that should work without a huge amount of expenditure!

[Chris.Morris]

If one is happy to use a carrier PCB with a module on top, a Teensy 2 or a Propellor Mini would both have mroe than enough PWMs, and are small, low cost, and can be built on a single sided carrier board. The question then becomes if the PWMs need to be buffered, but even if they do, its only six opamps, 3 duals, still in single sided board territory..

These days there's even a DMX Libary for arduino, not that I can claim to have used it.

[DrV]

These days there's even a DMX Libary for arduino, not that I can claim to have used it.

 

Indeed there is although it needs a minor mod to make it work with a Uno, but if you combine it with the example sketch which creates a six channel LED dimmer, you are 80% of the way there!