Workflow:

When the eclips is near totality, the mechanics that makes the eclips trigger the first micro-switch. The application, through an object of class LPeriodical, receives the signal and starts to instruct the Lightec to dim the channels 1 to 10 to zero, channels 11-12 to 20% and starts one other LPeriodical object (LSoundFader) to fade the music. When this object receives time through the method SpendTime() it compares the current sound level to the target sound in function of time. After rounding the value, an embedded AppleScript is run to send an AppleEvent to iTunes to set the audio volume to the desired value.

When the eclips totality ends, the second micro-switch is triggered and the application instructs the Lightec channels 11-12 to dim to 100% and to set gradually the sound level to 100% using the same LPeriodical objects. For Lightec channels 1-10 "missions" are generated randomly, this means that a target level and a target duration are computed by a random generator between a upper and a lower limit for each channel and that each mission is send to the Lightec. When a mission ends a new one is generated in the same way. Secondarily each channel is simulated on screen.

The G3 Macintosh is started automaticaly each morning at 10am when the museum opens and shuts down in the same way when the museum closes at 5:30 pm after simulating about 225 eclipses. Six days a week and 56 weeks long will bring the number of eclipses over 75000.

Hardware:

G3 PowerPC Macintosh

with Keyspan Serial Card. We have choosen the card above the USB converter to reduce the number of cable connections.

Lightec dimmer.

This 12 channel dimmer is driven through a serial port. Each channel can be instructed to reach a given level of intensity in a given time.

MacIO II
interface box

with two micro-switches. This box was connected to the second serial port of the Keyspan Serial Card.

Serial interface cable
to link to the Lightec dimmer. A standard Din8 to DB9 cable was used.

And everything had to take place into a small cabinet in the decor:


The eclips generator. A DC motor is used to give motion to a wheel where disks are attached. The diameter of the disks is the size of light bundle of the projector.

Two vitrines with music instruments are illuminated by five lamps each. Each light is driven by the Lightec's channel 1 to 10. Two rows of cubicles are illuminated by lamps driven by the Lightec channels 11 and 12.These latest only has to be dimmed when the eclips reaches totality.

An audio amplifier takes the audio output signal of the G3 Macintosh to be amplified and redirected to the sound boxes. The original music from cassette was transfered to an audio CD as one (about )50 minutes long track which was imported to the G3 Macintosh hard disk in MP3 format. The MP3 file is played continuously by iTunes 2.0.4 (freeware from Apple Computer)

Software:

PowerPlant custom application. PowerPlant is a framework that comes with CodeWarrior IDE (Integrated Development Environment), a Metrowerks product. The very high quality of the documentation has been a basement of this success story. We have choosen to run the application in the Classic mode of MacOS 9.1.

iTunes 2.0.4 for running the music, driven by embedded AppleScript from the application. I want to take here publicly the opportunity to thank Michael Kisor for his contribution on the embedded AppleScript.

Workload:

Two days of programming where necessary to implement the base program and four extra hours where necessary to fine tune the application and environment at the museum location.

Links:

web site of Tintin

Musées royaux d'Arts et d'Histoire

Koninklijke musea voor Kunst en Geschiedenis

Apple Computer

Keyspan

Lightec