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Why do all automation controllers seem to have a maximum of 16 relay contact closures

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  • #16
    In the beginning Kodak used I think 4 relays to simulate projector cues. I guess they had their pre-show system looking like a projector to some equipment. So we had designed it to insure that you could change multiple relays simultaneously and time their contact closures to the millisecond. The JNIOR still has that capability with the internal relays. The 312 came along after Kodak. They were happy with the 8 relay outputs back then.


    • #17
      It really depends on the system as to what constitutes enough relays. With 4 relays, you've really just covered conventional light presets. If the theatre has masking (and there shouldn't be an "if" there we are), then 4 is insufficient. And then it really all depends what the cinema system is supposed to control (and what voltages/current it might need to control).


      • #18
        I run a 3 screen complex without any contact closures whatsoever. We don't have masking, and both audio and lightning are done via ethernet.

        Just boggles my mind that anyone would want to control lighting any other way in this day and age. I can control any lighting circuit in the complex, set a custom brightness if I want, and a fade time. Example, when the credits start, I can have it jump quickly (3 seconds or so) to around 30% brightness, and then set a custom fade time that by the time the credit roll comes up, the lights are just hitting 100% brightness. For auditoriums with more than 1 circuit (think main lights, accent lights on the walls, track lights on the floor, and high power cleaning lights) you can do some fun automations with. Lutron is the pretty much the defacto lighting control system used in most high end commercial and residential builds in North America. We use a RadioRa2 system as we're quite small, but most commercial places would use XPS, LCP, or Energi Savr Node. Can all be controlled over Telnet or RS-232.

        I got our Ra2 system on eBay for pretty much pennies. The controller/main repeater was around $400 (they go for $200 now), and each dimmer - which is just the size of a standard lightswitch - was around $30 (they go for about $75 now).

        All the info to integrate to a server is available in here:

        If I wasn't using this, I'd definitely recommend a DMX based system.


        • #19
          Justin...consider are converting an existing theatre like we did from 2008 through 2015ish, and they already have a dimmer and lights. In the USA, by FAR, the most popular type lighting system was some form of triac based (Kelmar, Xetron, ASH, SPECO, EPRAD...etc.) that had contact closure control because, well, that is how film automations worked. You have 4-hours to swap a film system over to digital. You could redo the dimmer system and lighting and rewire all of that...or... put in an automation system like the eCNA or JNIOR, that you would have pre-configured for the server/lighting system that was in place and put it in within a couple of minutes and moved on. You don't even need to reset the light levels...they were exactly where they were.

          We often changed the sound processor but I'd say most or a lot of people didn't do that...they put in a box like the DAX602 and kept the sound the same for the same reason...the sound is all calibrated and most film sound processors had some form of aux 6-channel input...and again, you have 4-6 hours from start to finish on each film to digital conversion (including alignment/calibration).

          As for dimmers today on new builds...I've seen it all. Everything from a DMX style on down to a conventional triac based dimmer controlling either dimmable lamps (least reliable/consistent) to LED drivers designed to take a chopped signal and drive specific LEDS...with everything between.

          We are taking to Eprad's LED dimming system. We already use their automation so the controller part is built in (but it will take contact closure from JNIOR or others). It uses their lamps but they dim to zero without flicker and, like you say, you have control over the level and rate, up to 16 zones and while you only have 4 presets (scenes) plus off, you can also set up offsets (e.g. go to Mid-1 level and then offset that down a percentage for this particular cue.

          Below are just 2 out of 16 channels that can be configured. Note, one can have up to 16 zones or 16 channels, in any combination up to 16. Most cinemas 1-4 zones will suffice but, in the case of the theatre below, there are several overhead lights with some being more decorative so more than one channel was needed and their levels are not necessarily the same.

          Screen Shot 2022-05-14 at 11.01.26 AM.png

          So far, the Eprad LED dimmers have been a winner for us. All of the problems of conventional dimmers with "dimmable LEDs" are gone. We even went through a nightmare at one site where the client supplied their own LED lamps that mount on the T-BARS and their own LED drivers...of which things didn't work. At least with a system like DMX or the Eprad one, it is a holistic system where controller/dimmer/fixture are all part of the system designed to worked together. And, you don't have to worry about batch-to-batch problems when a manufacturer of "dimmable" LED lamps doesn't dim like the other batch or isn't compatible with your particular dimmer.

          Back to the relay thing. As mentioned, we use the relays for all sorts of things and probably more than most. There is nothing wrong with not using any relays, as you just indicated. But, if you had maskings, curtains, old style dimmers, a lamp exhaust, a sound rack, perhaps the projector and just might want a gaggle of relays at your access to control all fo those things.


          • #20
            Technically, you could implement a lot of this stuff using ZWave too, as long as I'm not on the call list if shit goes haywire, I'm perfectly fine with that. :P


            • #21
              You might be able to command the automation through Ethernet but at some point you're possibly toggling a relay (dry contact or solid state) anyway.


              • #22
                Originally posted by Bruce Cloutier View Post
                You might be able to command the automation through Ethernet but at some point you're possibly toggling a relay (dry contact or solid state) anyway.
                Technically, yes, through the relay would be inside the actual switch/dimmer. These dimmers have the same form factor as a run of the mill light switch, and communicate with the controller wirelessly.

                maestroleddimmer.png 41k2H-NtKRL._AC_.jpg


                • #23
                  One issue is that in most locations houselight must tie into the fire alarm system and most wall box dimmers dont do that nicely and a contactor accross them often causes a DVDT spike that damages them


                  • #24
                    Never had an issue with tying a digital booths automation into the fire alarm system. The Eprad automations do it easily and they can be networked so that if one theater has an issue the rest of the the theater(s) follow suit and all are evacuated from the building. In older film installations, we used the cue detector drop arms through what ever automation was installed. Always used Kelmar or Eprad dimmers. Emergency lighting happened at the same time the fire alarm activated. In addition a line back to the booth from the main fire alarm box shut down the show and brought house lights up. So we basically had a backup for the emergency lights. All this was inspected by the Fire Marshall before a new site could open.
                    Last edited by Mark Gulbrandsen; 05-20-2022, 07:42 AM.