Auto patch dimmer packs

[karl]

I read the recent thread on combined IWB and dimmers and it reminded me of an idea that crossed my mind a few months ago. I wondered whether my idea already exists (I couldn't find anything in Google but maybe I wasn't using the right terms) and if not whether there were reasons why it couldn't work.

 

Basically my thought was for 6 way dimmer packs (e.g. Betapacks) where each way of dimming can be switched between two (or more) outputs. So each pack has six ways of dimming (with each controlled by one DMX channel) and twelve separate outputs. There are two outputs for each dimmer circuit so outputs 1A and 1B would relate to dimmer 1, outputs 2A and 2B would relate to dimmer 2 and so on.

 

One or two additional DMX channels would be used to route the dimmer ways to the outputs. So dimmer 1 could be outputting through 1A or 1B or both depending on the value on the controlling DMX channel.

 

The idea being that normal non-auto-patched dimmer packs could be used for washes whilst the switchable version could be used for all those specials which only get used for a couple of minutes (or seconds) but hog a whole dimmer way.

 

I regularly work in two different venues that each have four dimmer packs (24 channels) which can be manually patched to 40 or 50 circuits. By the time you've got your washes, house lights, etc. patched there never seems to be enough left for the specials and the dimmer packs aren't easily accessible to repatch during the show.

 

I suppose and alternative would be a freestanding auto patch box that takes the output from a dimmer and distributes it out under DMX control. This would allow existing dimmers to be extended with auto patching.

[rossmck]

That somehow reminds me a lot of the way some of the small resistance dimmer boards worked - like the Junior 8 with 4 dimmers but 8 outputs and you could switch them between dimmers... these also had a "full on" option which meant that you could fade a channel up and then take it off the dimmer (leaving the light on) and use it for another channel...

 

However I think these arose due to the high cost of dimmers... now I imagine that if you consider the additional cost of the control circuitry you describe, and complexity that's added for plotting (not to mention the increased channel footprint) that it'd be easier just to buy an extra dimmer rack.

 

As an aside - I work in a number of small venues which, before they got proper install dimmers, used to work exclusively off Alphapacks... these have found a new lease of life getting used occasionally as specials (sometimes hung off the bars near where they're needed) to give us more channels when and where we need them.

[IRW]

I read the recent thread on combined IWB and dimmers and it reminded me of an idea that crossed my mind a few months ago. I wondered whether my idea already exists (I couldn't find anything in Google but maybe I wasn't using the right terms) and if not whether there were reasons why it couldn't work.

 

Basically my thought was for 6 way dimmer packs (e.g. Betapacks) where each way of dimming can be switched between two (or more) outputs. So each pack has six ways of dimming (with each controlled by one DMX channel) and twelve separate outputs. There are two outputs for each dimmer circuit so outputs 1A and 1B would relate to dimmer 1, outputs 2A and 2B would relate to dimmer 2 and so on.

 

One or two additional DMX channels would be used to route the dimmer ways to the outputs. So dimmer 1 could be outputting through 1A or 1B or both depending on the value on the controlling DMX channel.

 

The idea being that normal non-auto-patched dimmer packs could be used for washes whilst the switchable version could be used for all those specials which only get used for a couple of minutes (or seconds) but hog a whole dimmer way.

 

I regularly work in two different venues that each have four dimmer packs (24 channels) which can be manually patched to 40 or 50 circuits. By the time you've got your washes, house lights, etc. patched there never seems to be enough left for the specials and the dimmer packs aren't easily accessible to repatch during the show.

 

I suppose and alternative would be a freestanding auto patch box that takes the output from a dimmer and distributes it out under DMX control. This would allow existing dimmers to be extended with auto patching.

 

:D

 

I've re-read your post three times now, and I think I can finally see what your getting at. I doubt trying to 'split' the two outputs on a channel would work, as I should imagine most would be simply wired in parallel behind the socket.

 

If I've understood you correctly, then the only way I can see of making your idea work would be to disconnect the wiring from the sockets, go through a couple of relays controlled from a switch pack and then wire back from each relay to each socket.

 

So, for example, the electrical path would look like:

http://www.irwdesign.com/br/diagram.jpg

 

Anyways, I think the easier (and probably overall cheaper) solutions would be to get some more dimmer packs or do some more pairing if you are that desparate for channels!

 

 

Edited to add diagram

[PoppaDom]

Surely by the time you have put in switching circuitry then you must be approaching what it would cost to just make it a 12 channel dimmer?

 

Dom

[karl]

I've re-read your post three times now, and I think I can finally see what your getting at.

Sorry, it was as clear as mud! But it isn't easy to explain.

 

If I've understood you correctly, then the only way I can see of making your idea work would be to disconnect the wiring from the sockets, go through a couple of relays controlled from a switch pack and then wire back from each relay to each socket.

 

So, for example, the electrical path would look like:

http://www.irwdesign.com/br/diagram.jpg

Yes, that's pretty much it. Why didn't I think to draw a diagram.

 

Surely by the time you have put in switching circuitry then you must be approaching what it would cost to just make it a 12 channel dimmer?

That could be why it hasn't been done. I just assumed that as you've already got a DMX decoder in the dimmer and the switching could be cheapish relays that it wouldn't cost that much more than a standard dimmer pack. But I suppose if you start making some dimmers with auto patching and some without you finish up supporting two different lines and lose the economies of scale.

 

One of these days I'll come up with a genuine good idea.

 

Edited to remove duplicate post caused by browser being slow and me being impatient

[david.elsbury]

The thing is, cheapish relays will also require an enclosure, plugs and sockets, and probably inspection by someone to double check they are up to scratch (if the person making them isn't able to say so themselves).

 

The other thing is that one output per dimmer is "standard". As soon as you start mucking around with auto-switching then a random tech walking in off the street may not have a clue as to what your box does and why half the specials in the rig "don't work".

 

:D

[karl]

The thing is, cheapish relays will also require an enclosure, plugs and sockets, and probably inspection by someone to double check they are up to scratch (if the person making them isn't able to say so themselves).

 

The other thing is that one output per dimmer is "standard". As soon as you start mucking around with auto-switching then a random tech walking in off the street may not have a clue as to what your box does and why half the specials in the rig "don't work".

I wasn't proposing to retro fit the switching (other than as a separate unit) to existing dimmers. I was just wondering if such a thing already existed and if not whether it was a worth while product or if there was some reason why not.

 

I can see that having dimmers with special behaviour might be an issue but if we apply that logic nobody would ever use anything new, like say moving lights, because other people might not know how to use them.

[david.elsbury]

but if we apply that logic nobody would ever use anything new, like say moving lights, because other people might not know how to use them.

Understood- but aren't we talking a one-off in one venue somewhere? Or are you proposing more of a commercial approach? If enough of them get out there, then fair enough- they'd become commonly known :D

 

I wasn't proposing to retro fit the switching (other than as a separate unit) to existing dimmers

Which is why I mentioned requiring an extra plug and 2 sockets and an enclosure per channel- more expense, by the time you may be approaching just being able to add more dimming ;)

[karl]

Perhaps I should just explain where my idea comes from and what I'm not thinking of doing.

 

A while ago I was lighting a show in a venue with 4x6channels of dimming. Ideally I could have done with more channels but there was no budget to hire extra dimmers, no convenient place to put them and no where to plug them in. As I sat scratching my head, trying to workout how to plug up the dimmers a thought struck me. Quite a few of the lights were specials which were only used once or twice.

 

So I had nine or ten specials each sitting on its own channel but only one or two were ever on at any given time. This seemed wasteful and it crossed my mind that being able to switch the dimmers between circuits would be handy. That was pretty much as far as I got with the idea before I turned my attention back to the job in hand.

 

Fast forward to the other day when I saw the thread about combined dimmers and IWBs. Oh, I thought, that reminds me about that idea I had. So I did a spot of Googling and failed to find anything so I thought I'd see if anybody on here knew of such a beasty. Or whether somebody could immediately spot a major flaw that explained why they don't exist.

 

I seem to recall some dimmers designed for 60hz supplies doing dimmer doubling by using each half of the AC supply to run different lanterns. OK, that's more versatile than switching one supply between lanterns but my idea sounded a lot simpler to do.

 

I wasn't proposing to start modifying dimmers nor am I planning to go into the dimmer building business. I'm not saying this is the greatest idea in the world - or even a halfway sensible one, I was just throwing it out there to see what others thought.

 

Edited for spelling.

[dbuckley]

I've written before how I used to do this back in my two preset days with a plank of wood with several sockets on it, and the relays of your design were replaced by an operator a set of cans away, who would operate the switches according to my calls.

 

I've since been thinking of building exactly what you suggest. The dimmer will be a three channel dimmer, with twelve socket outlets, and each dimmer channel can be switched to one of four sockets by relays. The innovative bit is that the box will act as a twelve channel dimmer, automatically engaging the right relays, but with the restriction that it has a first takes priority system over the four relays per dimmer channel. So for specials you just arrange them so that there are no overlaps in any of the group of four relay loads per channel, and then just plot and use as a real twelve channel dimmer.

 

I think a dozen relays will cost less than nine decent quality dimmer channels for a homebuilt system.

[karl]

In terms of the extra cost involved in adding the switching element I was thinking (in so far as I had thought about it) in terms of a newly designed product - say the next generation Beta pack or what have you. If it was designed in from the start I can't believe it could possibly be that expensive to do. Forget the relays just give the dimmer circuit two SCRs and soft switch the outputs that way.

 

OK, your dimmers wind up costing a few pounds more to produce but it gives you a good selling point.

 

Now, one thought which has just sprung to mind is that with these dimmers people wouldn't need to buy so many so you won't sell so many. But, I suspect a lot of buyers will be bound by a budget so whilst they might like five or six racks they can only afford four (unless of course they buy cheapo tat in which case you've lost the whole sale).

 

Not sure how you'd manage the control of the switching though. I thought one DMX address per 6 dimmer channels would suffice (1 bit per channel so 00000000 on the control channel switches all outputs to their A socket, 00000001 flicks channel 1 onto its B socket, 00001010 flicks channels 4 and 2 onto their B sockets, and so on.) Trouble is setting this value using a simple desk isn't going to be easy (if it is even possible). If you have to buy a big expensive desk that supports intelligent fixtures just so you can run 24 dimmers then that kind of defeats the saving you made on the dimmers.

 

OK, I think I've talked my self out of the idea.

 

Sorry, I'll stop rambling now and go to bed. :D

Edited to fix typo

[musht]

ETC has dimmer doubling using 77V lamps on a 110V system using each halfwave, weird system

 

http://www.ies.nl/Community/wikis/products...r-doubling.aspx

 

All the money in building a dimmer is in the high current side, have as many outputs as you want form the 25p micro in the middle.

[kitlane]

Back in the olden days of D54 running off a Galaxy II at Derby Playhouse we had a homebrew switchbox which could remotely switch between a handful of channels.

 

Is there not an argument that if a venue can't afford an extra dimmer pack it also probably can't afford the additional incoming mains supply and distribution required to power it? This might be an application for a dimmer with switched outputs.

[PoppaDom]

Back in the olden days of D54 running off a Galaxy II at Derby Playhouse we had a homebrew switchbox which could remotely switch between a handful of channels.

 

Is there not an argument that if a venue can't afford an extra dimmer pack it also probably can't afford the additional incoming mains supply and distribution required to power it? This might be an application for a dimmer with switched outputs.

But they do not necessarily need additional mains supply. What they would need to do is split the supply going to dimmer 1 to power dimmer 2.

 

If we are talking about the OP's original application then we are talking about number of channels needed not additional power. Diversity is a great thing.

 

DOm

[karl]

But they do not necessarily need additional mains supply. What they would need to do is split the supply going to dimmer 1 to power dimmer 2.

Certainly you could just split the power but you'd have to be careful then never to run both dimmers to capacity. At one venue I know it's not uncommon for the director/SM to just whack all of the channels up full for rehearsals if there's nobody technical in that night. That sort of thing might be an issue.

 

Power is a minor issue though, the main things are cost and space. If the majority of your shows can be handled using X channels it's daft buying X+6 channels worth of dimming and having one pack sit idle most of the time. Equally if you only buy X and then have to hire more in then that's extra expense and hassle. Also you need the space to accommodate the extra dimmers (either bought or hired). In many small venues space is at a premium with dimmers stacked on top of cupboards or under benches, etc.

 

The venue I was at when I had the idea has its dimmers locked in a cupboard under the control room desk (unfortunately the cupboard is only accessible from the auditorium hence the problem with repatching). There is no spare room for extra dimmers and the existing dimmers are hardwired. Putting extra dimmers elsewhere (such as attached to the bars or backstage) would require additional cabling and such like. Adding dimmers could be done but wouldn't be as simple as plugging it in to a splitter.