Film-Tech Forum ARCHIVE: Replacing a single-gang dimmer switch with something automated?

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Posted by Andrew Thomas (Member # 7000) on 08-13-2016, 09:16 PM:

Ok, so this crap-hole theater doesn't have automated dimmers like a kelmar or some such, just manual sliding single gang dimmers. We want to switch over to kelmar like we have at our other theaters, but I'm wond ring if there are any stop-gap solutions I could put into the single gang box now that a Jnior could trigger?

Posted by Dave Macaulay (Member # 813) on 08-14-2016, 10:37 AM:

Well, there's X10 signal on powerline ... but getting it to work from a Jnior won't be simple. They sell an X10 serial-to-wireless adapter that talks to an X10 controller plugged into a wall outlet. The serial API is available online, I haven't tried to use it or program a Jnior for it. There's a PC program available though: you could run it while sniffing the serial data.

I have friends who have X10 for home automation and use the serial adapter on a PC, via the X10 software though.

Far from being Crestron but X10 is quite flexible. The signals cover a house well, they will get blocked by transformers so any other houses/businesses sharing the transformer can see your control signals and potentially control your stuff. There is no security - know a device's house code and device address and you pwn it if you can get at the power wiring.

Posted by Jim Cassedy (Member # 4115) on 08-14-2016, 11:04 AM:

It would be helpful, for the purpose of making suggestions,
if you could give some idea of how much of a load (watts or
amps) you need to control.

Posted by Tony Bandiera Jr (Member # 2365) on 08-14-2016, 12:18 PM:

Jim, a single gang slide dimmer is rarely if ever rated at more than 600 watts... (about 2 amps at 120v.) There are some that go up to 1,000 watts but they usually take up two gangs of space (mainly from the external heat sink fins).

One possible solution if you can search ebay a bit is to get the AMX/Radia/Panja (all three are the same, just different branding) Dimmer setup..you can find one that controls 4 or 6 circuits ("Channels" or "zones" in dimmerspeak) relatively cheap. Get the ones with the 120v control circuits... (they make a 277v version as well). Models are RDD-DM4/120 or RDD-DM6/120

It will wall mount in a can similar to a Kelmar...

Here's the one I have at the house:

The module on the left is an auxiliary control module for the module on the far right, which is a dual relay module. The dimmer module is in the center. (4 channel). It can be controlled by the AMX keypad for the dimmer system, an AMX automation system, or by dry contact closures. The dry contacts are the option you want to use.

****Note: The single gang items you'll see listed as "Dimmers" on ebay are NOT the actual dimmer, but are the control pads FOR the dimmer units..don't buy one and try to connect it direct, it will burn up!**** Also, the Panja line (and it's sister, Phast) are NOT compatible with the unit I suggested.

If you can't find one on ebay contact me as I have a source in L.A. that might be able to get one for you.

Posted by Frank Cox (Member # 6258) on 08-14-2016, 02:05 PM:

If you're planning to install a Kelmar switch, why would you spend a bunch of money and time on a "stopgap" solution instead of purchasing the Kelmar?

Posted by Randy Stankey (Member # 64) on 08-14-2016, 05:13 PM:

I don't know how the lights in the auditorium are wired but, if they are all on one dimmer, now might be the time to consider breaking them up into two or more circuits.

As it is now, all that current is going through one dimmer. As others have said, that limits the wattage/power that can be carried through a circuit. Further, if one switch, dimmer or breaker fails, all the lights in the house will go out. Splitting the lights into two or more circuits will solve the "eggs in one basket" problem.

Since you are now considering how to upgrade the dimmer system, it would also be a good time to consider whether you should rewire. Maybe the building is constructed or wired in such a way that you can't change it but I think you should at least look into it.

I agree with Frank. Get the dimmer/equipment you want now instead of trying stop-gap solutions. Better to do a job one time, the right way, than to spend time and money doing a job twice. [Wink]

Posted by Leo Enticknap (Member # 534) on 08-14-2016, 10:35 PM:

Surely there has to be a battery or genny-maintained lighting system in this house to enable a safe evacuation if the power goes out? I'd be astonished if neither state law nor city codes required it. I know he said the place was a craphole, but if all the house lights in the auditorium are going through a single-gang consumer grade dimmer unit from Home Depot, it's at risk of suddenly becoming a very dark craphole, I guess!

That having been said, if the house lights have dimable LED bulbs in them, 600w is probably enough, unless it's a pretty big house. In one of our auditoria we have 24 20w LED PAR38s for the house lights - 480w if they're all on full (which they almost never are). They're on a proper Kelmar box which is fed by two circuits, though...

Posted by Andrew Thomas (Member # 7000) on 08-15-2016, 12:43 PM:

A little more info.

The dimmer in each auditorium are controlling 6 wall sconce fixtures with 60 watt bulbs in each. These are small rooms. Additionally there are 8 overhead 4x4 48" fluorescent "cleaning lights" on a separate circuit. Those are actually already controlled (simple on/off) by the projector/jnior.

The install of the kelmar dimmers will be part a much larger remodeling project, so I don't want to pay a bunch of money for the required electrician to install only for them to have to be re-done in a few months. The single gang dimmer swap is something I can legally do myself.

The emergency lighting system is completely separate of these fixtures.

Posted by Carsten Kurz (Member # 5396) on 08-17-2016, 08:46 AM:

Maybe add a motor/RC servo drive to the existing pot?

Some dimmer pots actually generate a 0-10V control voltage. It would be safe to replace it with a remote controllable electronic device. But if the pot is connected directly to the dimmer circuit, I would be very careful to mess around with it, as there is mains involved. So adding an external mechanical drive is just safer.

You can get those small RC model servos for a few bucks, and driving them forth/back only is very easy.

- Carsten