Film-Tech Forum ARCHIVE: Automating the EL-40

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Posted by Rick Long (Member # 213) on 04-28-2003, 10:39 PM:

Spring fever has once again broken out here and I am too lazy to think of what will probably be an all-to-obvious solution to this problem, so I throw it out to those who haven't yet suffered from this malady.

Strong Highlight II console.
Simplex projector (1060) and 5-star sound-head
TA-10 automation.

In equipping these units for the up and coming (this time for sure, or so we have been told, again) the dreaded cyan sound-tracks, we are using C.E.'s kit for converting from the infa-red to bright-red l.e.d. units. To save us the time of converting the EL-2A supplies (which we are quite capable of) to prevent l.e.d. burn-out if incorrectly polarized, we have instead been given the EL-40 units.

The 40's are quite compact, (although I wish they had made them mechanically replaceable for the EL-2A's).

The thing is this: In the past, in order to preserve the 770nM life in other units, we had simply wired the power line of the EL-2's across the motor "on" terminals at the automation. Thus when the motor came on, the exciter came on also.
If you happened (seldom, but it could happen) to turn on the motor with the cinema processor in an optical format, it created a "thump" which not only woke up the audience, but cleaned the cobwebs out of the speaker systems. Mind you, we are de-powering the pre-amps at intermission too - not really sure if this is a good thing although there have been no failures in almost 100 conversions.

The 40's however offer an intriguing possibility. Two 1/4" push-on terminals offer a way in which;
(a) if the terminals are not connected, the l.e.d. will remain on.
(b) if the terminals are shorted, the l.e.d. will turn off
Not only this, but there is a "ramp" to the on and off conditions that prevents that "thump" in the speakers.

I am trying to come up with a simple way in which this could be used for both automatic and manual running conditions. Please bear in mind that these are used by less-than experienced operators so the addition of an extra switch for them to operate is NOT a good idea.

I have thought of putting a 110-volt relay across the motor "on terminals and wiring these two lugs to the normally closed contacts of the relay.

Is there a simpler solution?

Posted by Stan Gunn (Member # 554) on 04-29-2003, 04:09 AM:

YOU CANT GET MUCH MORE IDIOT PROOF THAN THAT [thumbsup]

Posted by Jean-Michel Grin (Member # 1360) on 04-29-2003, 05:12 AM:

I think you could use two solution:

Using a Bi-stable state relay and connecting it in parallel with the changeover control command

or,

Using a delayed relay in parallel with the "motor On" command. In this case pay attention to check that the TA-21 automation system give a pulse to the sound processor to switch it in non-sync format to prevent what I call "the famous tail-out sound !" in the theater.

I hope that can hel You.

Sorry formy weak english !

best regards

Posted by Steve Guttag (Member # 268) on 05-01-2003, 08:49 AM:

Wanna place your bets on the cyan prints getting a wide release this year?

Steve