Lamping S4s at 550W

Sweet Chart! They had one on the counter at the local electrical supply place... with the help of my plotter I can print one bigger than theirs!
 
in memory, if one should go dimmer duplexing, there is a standard 6" Fresnel lamp for such a system available that should work. On the other hand, good luck with other fixture types. That's the type of thing you might have to deal with in such a system. Want to add a scoop somewhere... possible with study into some kind of lamp that might work, on the other hand not persay plug and go.
 
My god! I never knew.
I don't believe this has come up on CB before?
Does anyone here use dimmer doubling? I've read briefly about it, but am not positive about what the deal is with it. Can anyone shed some light on it? And why does dimmer doubling necessitate the move to a 550W lamp?

For those techie people out there, here is the physics of dimmer doubling, which actually would work with Triacs, SSRs, IGBTs, as well as SCRs:

Normal Dimmer 101:
An AC waveform (120v) Starts out at 0 volts, swings positive to over 200 volts, swings back through zero and swings all the way to over 200 volts negative before returning to zero. If you do the RMS equation, the R.M.S. gives you the classic 120 volts. (Root Mean Square)

Conventional dimmers use a device to detect the “zero voltage cross point.” When that point occurs, a digital timer starts that counts down from 255 to 1 in 1/120 second, the same time interval until the next zero voltage cross. If your dimmer is set to a dmx value of 127, the control module sends a pulse to the thrysistor (SSR, SCR, Triac, or IGBT) when the two values match to turn it on. Thus, about 50% of your power is allowed to pass each waveform, and the dimmer is said to be at 50% (In practice, there are data conversion tables to adjust these values to give you different dimmer curves.) The higher your DMX value, the sooner your thrysistor turns on and the brighter the light is as there is more power passing.

Dimmer Doubling:
This is actually a minor software and hardware change. The zero voltage detector also sets a flag indicating if the waveform is headed positive or negative. A separate count is made depending on the direction so that the positive waveform is controlled different then the negative waveform. The output of the channel is then passed through a diode set to divide channel A from B. As half of the waveform is missing, the RMS value is shifted. (Thus the low voltage lamp.) Even though the waveform is going from zero to over 200 volts, its total R.M.S. value is now about 60 volts.

As you can see, it would not hurt a dimmer if a conventional light were accidentally attached, but it would destroy a 77 volt lamp if it were connected to a “normal” dimmer, so the control of the environment which this is used is critical.
 
So, has anyone on this forum used such a system personally? I'm seriously looking into here at our "theatre" so we can double up the amount of DS lights we've got to keep people happier w/ their riders..
 
So, has anyone on this forum used such a system personally? I'm seriously looking into here at our "theatre" so we can double up the amount of DS lights we've got to keep people happier w/ their riders..

Well, the thing about DD is that, while it is nce and convenient for something, it is a hassle for others. You can't pick and choose your DD dimmers, it is all or none for each rack. Then of course you have to deal with the special twofers and you can only use DD ready fixtures. If you can commit to all of that then it may work out for you.
 
Hmm I wasn't aware you couldn't pick and choose DD dimmers.. I was thinking for example that I could set dimmers 1 thru 24 to DD and leave the rest alone.. so I can see where it really would become a major commitment and hassle to set all your dimmers that way.. thanks for the info..
 
You can't pick and choose your DD dimmers, it is all or none for each rack.

Not sure that is exactly true. As some may know, our space is currently undergoing a system upgrade. According to Barbizon, you can pick the dimmers that are going to be dimmer doubled on the screen of the Sensor Racks. Dimmer Doubling is an important part of our Dance Space since overages forced us to cut extra dimmers so we double and triple checked this issue. So the new rack will enable us to add one more system of lights without actually adding dimmers.
 
I have read all of the posts in this thread so far and I have a question.

Say you have a lighting grid that is DD ready, and you want to set certain dimmers to allow non-DD fixtures. Can you go into the CEM to revert the Dimmer back to a standard 120v dimmer?
 
I have read all of the posts in this thread so far and I have a question.

Say you have a lighting grid that is DD ready, and you want to set certain dimmers to allow non-DD fixtures. Can you go into the CEM to revert the Dimmer back to a standard 120v dimmer?

All recent ETC Sensor dimmers are DD ready. Note that they must be ETC Sensor (I don't think the Smart line allows DD, too lazy to look). Any dimmer can be selected in the CEM to DD or not.

SB
 
Ok, that's what I'd thought I'd read was that each individual dimmer was selectable in the Sensor system; but maybe I misunderstood Icewolf.. also, ETCs stuff seems rather vague on these points sometimes. Are the dimmers easier to pick out on their Sensor+ Connect GUI?
 
...Are the dimmers easier to pick out on their Sensor+ Connect GUI?
"Easier" is a loaded term.

To me, nothing could be "easier" than on a standard CEM (non plus): [from memory here, not all keystrokes may be correct] <setup> <dimmer> <dim#> <enter> <right or left arrow through "normal, switched, non-dim, etc." until "DD" is displayed> <enter> <exit>. No plugging in a laptop, nor dealing with non-intuitive icons such as "light bulb" and "check mark." (The author dislikes immensely the CEM+, as previously noted.)

As I understand it, and I admit to never having used DimmerDoubling, the hardest part is remembering to softpatch correctly.
For instance, one has a rack of 96 dimmers, and only dimmer 96 is set as "DD". Dimmers 1 thru 95 are DMX addresses 1 thru 95, dimmer #96A is DMX 96, dimmer #96B is DMX 352 (257+96-1). DMX addresses 97 thru 351 and 353 thru 512 ARE available for other purposes, BUT, if one later decides he wants/needs to set another dimmer to "DD" it may very well fall right in the middle of one of the moving lights, or another dimmer rack!

ETC desks offer assistance with keeping the numbers correct, but ETC desks ARE NOT required to take advantage of DimmerDoubling. Only Sensor dimmers support DD, SmartPacks do not.

I'm not knocking the concept--it was very innovative of ETC (and one of the few that has not been copied), but be beware "TANSTAAFL".;)
 
As you can see, it would not hurt a dimmer if a conventional light were accidentally attached, but it would destroy a 77 volt lamp if it were connected to a “normal” dimmer, so the control of the environment which this is used is critical.


So here is the question no one has asked.

What would happen if a 'conventional light' were 'accidentally attached'?
;)

Since it would not hurt the dimmer, what would happen to the lamp and fixture?
 
My question is this: Do I still have a 2.4 kW limit on the dimmer itself? It seems that I ought to... So I would still only be able to connect 2 or 3 Source 4s to the dimmer (looks like 3 would be the normal situation), and just get 2 channels of control instead of 1?
 

As I understand the physics, you would get 1.2 K per each side of the [autolink]dimmer[/autolink]. IE if you name your outputs 'A' and 'B' you could put two lamps in A and two in B. You could not put one in A and three in B.
 
...What would happen if a 'conventional light' were 'accidentally attached'?...
Providing an HPL575/115 lamp with 77V instead of 115V would result in luminous output of 7700 instead of 16500 lumens (~47%).

My question is this: Do I still have a 2.4 kW limit on the dimmer itself? It seems that I ought to... So I would still only be able to connect 2 or 3 Source 4s to the dimmer (looks like 3 would be the normal situation), and just get 2 channels of control instead of 1?
Current specifications say one lamp per side.


See also the thread http://www.controlbooth.com/forums/lighting/14163-dimmer-wiring.html.


[Edit: JChenault beat me to it, but I had already done the math and typed everything. Kudos.]


So you need to load it evenly?
No, you can have one lamp(s) on one side and zero lamp(s) on the other.:cool: Others have successfully used two lamps on one side and one on the other, and even two lamps on each side, but perhaps not with the newest of dimmers.
 
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