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This topic comprises 2 pages: 1 2
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Author
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Topic: BACP RSTR 2000 changeover operation with no Cinema Processor
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Daryl C. W. O'Shea
Film God
![](http://www.film-tech.com/ubbmembers/1303c.jpg)
Posts: 3977
From: Midland Ontario Canada (where Panavision & IMAX lenses come from)
Registered: Jun 2002
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posted 09-21-2004 08:58 PM
What would be the best, err, most convenient yet acceptable, way to wire up two BACP RSTR 2000s in a changeover situation without a cinema processor?
Being a drive-in, they don't want to spend the money on a CP, which I can't say I blame them. Instead both channels from both readers are going to be attached to 4 XLR inputs on a very good mixer.
The current exciter lamp setup has a General Sound DC power supply that either runs the exciter at full voltage on the active projector, and dims it on the non-active projector. The outputs of both (mono) cells are currently tied together after their individual preamps. There's also a 20VDC power supply to run the preamps.
The easiest simplest way I currently see possible is to use the existing preamp power supply to pull-in or release a relay in each of the sound heads. Either the LED power lines, or the audio lines, would be connected or disconnected, depending on the active status. For obvious reasons I'd like to avoid splitting up the audio lines and instead shut off the LED. I'm assuming the GS exciter supplies wouldn't like to only have a relay as a load. Please correct me if I'm wrong (Gordon?), because using that supply (if I can turn the exciter warming voltage/current right down) would be the easier way to go and I could keep the existing changeover switches.
So, my questions would be...
1. Can anyone recommend a circuit to put in line with the LED and the BACP RSTR 2000 reader so that the LED ramps up, rather than goes to full current/voltage right away?
2. Does anyone (Sam?) know if there's a way I can just open/close some point of the BACP circuit, similar to the Kelmar or CE designs, to turn the LED on or off?
3. Not quite related -- these folks like to 'bump' the projector motor (Century CC on an R3) when threading up. If I were to wire the BACP power supply across the motor is it going to be a problem. Some supplies and ciruits will handle that sort of abuse, others won't. If it can't handle it, no big deal, at least they'll have one LED off at all times and don't have significant off screen time with the booth powered up, being a drive-in.
Keep in mind that I've never seen one of these BACP readers and only know what the manual says about them.
Thanks!
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Ron Yost
Master Film Handler
Posts: 344
From: Paso Robles, CA
Registered: Aug 2003
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posted 09-22-2004 12:58 AM
Mine, operated by the same switch I used to use for the exciter lamp, 'snaps' on very rapidly. I'd say it's near-instantaneous, practically speaking, and there's no visible or audible delay, that I can discern. It's just 'there' the instant the switch is thrown. Is that what you mean, Daryl?
I'm using the wall-wart supplied with it, tho, if it matters.
This is in my home 'screening room', with only the one machine.
Technical answer, huh??
Ron Yost .. NotATech, Inc. is not responsible for this message.
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David Buckley
Jedi Master Film Handler
Posts: 525
From: Oxford, N. Canterbury, New Zealand
Registered: Aug 2004
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posted 09-22-2004 08:01 AM
Lurking inside the 1970s "hifi" amplifier that is our "processor" I found this:
![-](http://www.film-tech.com/uploads/uploads0503/relaybrd.jpg)
Its a relay that basically switches the stereo audio. There is also a preset for each channel of each projector, so they can be balanced up. Its controlled from a switch on the soundhouses, which looks an original switch from the mono days, thats been rewired.
It may be ugly, but it does work, and whoever built this thing selected a relay suitable for low level signal switching. It doesnt click, or miss changeovers.
The other components on the board are a simple regulator that drops the amplifiers 55v rail down to 24v for the optical preamps. Oh yes, they are home made, too.
![-](http://www.film-tech.com/uploads/uploads0503/notleds.jpg)
Its a comforting thought that with cyan upon us, in the summer break we'll be upgrading these readers to something resembling a commercial product.
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Ron Yost
Master Film Handler
Posts: 344
From: Paso Robles, CA
Registered: Aug 2003
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posted 09-22-2004 05:09 PM
Yeah, Daryl .. I think that's what Sam means. To see what would happen, I just this morning tried 'inerting' a little SPST switch (adequately rated, of course) in one of the LED's leads and switched it quite a few times. Left it off for a half hour or so, too. It worked just fine .. nothing made any sign it wasn't happy when the led was off. I'm going to use this newly-learned knowledge in my own little setup. Thanks, Sam!
I didn't have my processor on, tho, so I wasn't listening to anything.
I assume you're planning on using the supplied wall-wart, right? If so, it's the type (mine is, anyhow) that has two AC prongs on the wart itself .. it doesn't have a cord that plugs into AC. Normal, for a wart, but I have some that do have a cord. Just thought I'd tell you so you can do a little advance planning where you're going to put it, if you need to. Your's, for Century's, may be different as far as the wart goes. I know it's entirely different, as far as mechanical design goes.
Thanks for responding, Sam. Always good to know what those that make 'em recommend .. or, at least, what an 'amateur' like me can get away with.
Ron Yost
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