Control/Dimming Temporary Install - Dimmer Connected to Dimmer?

DotNM

Member
Hi there,

I'm preparing for a short-run show (3 days) for which we will be renting some DMX-controlled lighting equipment. The venue has an older non-DMX lighting system already installed and we'd like to also use these fixtures from the same console if possible.

For a temporary setup, would it work to have the house fixtures connected to our rental dimmers, which would be connected to outlets which run through the existing non-DMX dimmers if we put them all to 100%?

Basically, the thought is this:

Fixture --> Rental Dimmer Pack --> House Dimmer (@ 100%) --> Hydro/Power

If this is possible, it'd save us some time and extra cabling but we can work around it if it's not possible or would cause issues. I was just thinking about this to save time and extra work.
 
Hi there,

I'm preparing for a short-run show (3 days) for which we will be renting some DMX-controlled lighting equipment. The venue has an older non-DMX lighting system already installed and we'd like to also use these fixtures from the same console if possible.

For a temporary setup, would it work to have the house fixtures connected to our rental dimmers, which would be connected to outlets which run through the existing non-DMX dimmers if we put them all to 100%?

Basically, the thought is this:

Fixture --> Rental Dimmer Pack --> House Dimmer (@ 100%) --> Hydro/Power

If this is possible, it'd save us some time and extra cabling but we can work around it if it's not possible or would cause issues. I was just thinking about this to save time and extra work.
Short answer: NO! Upper case exclamaion point!
To reiterate: That's NO! Don't do it! Don't even think of doing it.
Toodleoo!
Ron Hebbard.
 
Best case, the Zero Cross detector would lag in the rental pack and cause the curve to top out at the wrong part. Worse case, the LV transformer in the rental pack would fry.
Ditto on the ! after the NO.
 
Hi there,

I'm preparing for a short-run show (3 days) for which we will be renting some DMX-controlled lighting equipment. The venue has an older non-DMX lighting system already installed and we'd like to also use these fixtures from the same console if possible.

For a temporary setup, would it work to have the house fixtures connected to our rental dimmers, which would be connected to outlets which run through the existing non-DMX dimmers if we put them all to 100%?

Basically, the thought is this:

Fixture --> Rental Dimmer Pack --> House Dimmer (@ 100%) --> Hydro/Power

If this is possible, it'd save us some time and extra cabling but we can work around it if it's not possible or would cause issues. I was just thinking about this to save time and extra work.
Your signal flow is backwards.

Also, NO!!! :)
 
What type of dimmer is house dimmer? You say non-dmx, but that could be a lot of things from salt water, resistance, auto-transformer, mag-amp, or solid state (triac, scr, other). Resistance or auto-transformer - you can probably get away with what you suggest. Salt water or mag-amp, I don't know. Solid state - probably the fire consequences noted above.
 
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What type of dimmer is house dimmer? You say non-dmx, but that could be a lot of things from salt water, resistance, auto-transformer, mag-amp, or solid state (triac, screen, other). Resistance or auto-transformer - you can probably get away with what you suggest. Salt water or mag-amp, I don't know. Solid state - probably the fire consequences noted above.

Bill

why are you concerned about salt water? I can't see how that could be an issue? I think mag-amp would work also. ( unless it simply used the mag amp to trigger a thyrotron or SCR system like the old Radio City Music Hall system )
 
What 'cha need is a Flux-Capacitor, tied to a left-phase Di-polar motivator. Port that through a Laswell Diode in a Stetson array as a crude cosmotron rectifier and that baby will be just fine.


DotNM, what is it you are trying to accomplish by running things this way. Is this a power issue? do you not have the service available? or are you trying do get DMX workability?
 
Bill

why are you concerned about salt water? I can't see how that could be an issue? I think mag-amp would work also. ( unless it simply used the mag amp to trigger a thyratron or SCR system like the old Radio City Music Hall system )
I wasn't concerned, I simply do not know what the output of the salt water and mag amp is - or at least not confident enough that its a clean sinusoidal to say do it without further consideration. It probably is fine, and probably sinusoidal. And I forgot thyratron as an option. I suspect that is also a pretty sinusoidal output. I also strongly suspect that it isn't salt water, mag amp, nor thyratron.

As far as what he wants to accomplish, I thought we wanted to control all of the lights from a console spitting out DMX, and that the house dimmer would not listen to DMX. There is of course the possibility that the house dimmers could be made to listen to DMX, and that should be easier, safer, and maybe less expensive than powering portable DMX dimmers from the house dimmers - unless resistance or auto-transformer.
 
Diving deeply into the weeds here.

. And I forgot thyratron as an option. I suspect that is also a pretty sinusoidal output.

My understanding (long ago and fuzzy ) was that a thyrotron tube was similar in functionality to an SCR

Anyone have an authoritative answer?

Update. Wikipedia is a wonderful thing. Here is what I found

A solid-state device with similar operating characteristics is the thyristor, also known as the silicon controlled rectifier (SCR). The term "thyristor" was derived from a combination of "thyratron" and "transistor".[2] Since the 1960s thyristors have replaced thyratrons in most low- and medium-power applications.
 
I hate to date myself this way, but here's the scoop on the thyratron tube:
Although the concept of the tube is similar to an SCR, there were two important differences:
First, a SCR is gated on by a pulse to the gate whereas a thyratron required a negative bias on it's grid to keep it from firing. As soon as that was removed, bang, it fired.
Second, they don't handle much current, so they were never directly used in dimming a load. Instead, they were used to control the saturation coil in a magnetic amplifier type dimmer. As such, the output of the dimmer was not the classic sawtooth like a SCR dimmer would be. Never scoped one out, (actual dimmers were before my time) but I suspect as the core saturated, the output waveform would diminish and square off a bit.

Must say, this has been the most fascinating off-topic discussion I have seen in quite a while!
 
Forgive me for trying to be helpful, but what type of control does the non-DMX dimmer use? It may be possible to get a converter.
 
I hate to date myself this way, but here's the scoop on the thyratron tube:
Although the concept of the tube is similar to an SCR, there were two important differences:
First, a SCR is gated on by a pulse to the gate whereas a thyratron required a negative bias on it's grid to keep it from firing. As soon as that was removed, bang, it fired.
Second, they don't handle much current, so they were never directly used in dimming a load. Instead, they were used to control the saturation coil in a magnetic amplifier type dimmer. As such, the output of the dimmer was not the classic sawtooth like a SCR dimmer would be. Never scoped one out, (actual dimmers were before my time) but I suspect as the core saturated, the output waveform would diminish and square off a bit.

Must say, this has been the most fascinating off-topic discussion I have seen in quite a while!

With all due respect, the thyratron was used as the primary device in dimmer systems once aupon a time. I actually lit a few shows in the EX at Yale when it was still thyratron dimmers. I know at least Dartmouth and Bates College had thyratron systems. I need to leave it to an historian to confirm if it was Century Lighting that manufactured these. George Izenour is generally credited with developing the thyratron theatrical dimmer.
 
I could very well stand corrected!
However, the Strand dimmers (prior to Strand-Century) were saturable core reactors, first driven by tube, then by SCR. (see article- http://www.theatrecrafts.com/archive/control/strandremotecontrol.html )
These Atlas dimmers DO appear to be full tube, but only run at about 6 amps http://www.electrokinetica.org/d4/5/1.php
It is not clear to me if these Strand dimmers are what you had, but that socket design tops out at 6 amps as well http://www.theatrecrafts.com/archive/bhc/exhibit.php?id=52
These are more the reactor racks I spoke of:
proxy.php
 
I recall much larger tubes, but I may simply be wrong. The tubes were about the size of a milk bottle.

PS-: the parent https://www.google.com/patents/US2548887

I also recall larger tubes. I ran and maintained a thyratron tube system in the 70's. It was definitely a Century install of the Izenour design, probably early 60's. This was at the Bonstelle Theatre in Detroit MI, part of Wayne State University. The system was replaced around 1980. Tubes were getting pretty pricey plus hard to find by then. There were two sizes of tubes for the two sizes of dimmers. 2.5k and 5k iirc. The console was a ten scene preset with split crossfaders. The preset panel to the side had ten rows of 50 little itsy bitsy dials(!) - backlit w/fluorescent tubes. Sorry for rambling...

The rack was pretty similar to this. The tubes look to be the 2.5k's.
http://www.theatrecrafts.com/archive/albumviewer.php?id=37&page=89&type=a
 
I also recall larger tubes. I ran and maintained a thyratron tube system in the 70's. It was definitely a Century install of the Izenour design, probably early 60's. This was at the Bonstelle Theatre in Detroit MI, part of Wayne State University. The system was replaced around 1980. Tubes were getting pretty pricey plus hard to find by then. There were two sizes of tubes for the two sizes of dimmers. 2.5k and 5k iirc. The console was a ten scene preset with split crossfaders. The preset panel to the side had ten rows of 50 little itsy bitsy dials(!) - backlit w/fluorescent tubes. Sorry for rambling...

The rack was pretty similar to this. The tubes look to be the 2.5k's.
http://www.theatrecrafts.com/archive/albumviewer.php?id=37&page=89&type=a
We had what sounds like the identical console in what, at the time, was Toronto's O'keefe Centre except there were 100 dimmers and two of the 50 channel wide preset wings. On busy shows the board was operated by a three person crew with the Head LX manning the cross-faders and two assistants straining their eyes on the "itsy bitsy dials". I never saw the actual dimmers but this would've been the same vintage. Strand Century Canada kept it in operation until the original, furniture, Palettes came out.
THANK YOU for your rambling...
Toodleoo!
Ron Hebbard.
 
One of those articles referred to "heater" and output transformers and while 6 amps - like 1500 volts - which would seem to get to decent wattage when stepped down. I'll confess - I never got into the electronics behind thyratrons.
 

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