Project Proposal

							Project Proposal: ECE 345, Spring 1999
Name: Jim Schneider

Project Title: Theatrical Dimmer Rack

Statement: My reasons for selecting this project are many. Firstly, I love all aspects of
theatre, and relating my design project to the theatre will allow me to enjoy it more.
Secondly, the finished project will be given to the Krannert Center Student Association,
an organization with which I am deeply involved. Thirdly, the project will be used in
KCSA’s productions of “On the Rocks,” a production with which I have strong ties: last
year, I co-produced it, and this year one of the plays being performed is one that I wrote.
Fourthly, the original engineers who worked on this project included two former
roommates and a very good friend, the latter of whom was also involved with KCSA and
who was disappointed that he could not deliver a working product. Lastly, I feel that if I
don’t being the dimmer rack to working condition, it will probably never happen, which
would be a great loss for KCSA.

Project Goals: The goal of the project is to deliver a working model of a theatrical
dimmer rack. The dimmer rack’s purpose is to receive digital input from the light board
(and therefore the light board operator) via the IEEE-RS485 protocol and output for each
of the twelve channels (lights) the proper amount of power. One design of the dimmer
rack has been tried and has failed, and the purpose of this project is to pinpoint the
problems with the previous design and to correct or redesign them.

Block Diagram:

Microprocessor  CPLD  solid state relay  light
                                                
                                             choke
                zero cross                      
               pulse circuit  transformer  120 Vrms

Functions:
      120 Vrms: power supply (standard outlet)
      transformer: step down the voltage for the zero cross pulse circuit
      zero cross pulse circuit: provide a signal for the CPLD whenever the input
               voltage crosses zero in order to turn on each light at the desired time
      microprocessor: receive input from the light board via IEEE-RS485
               communication and output to the CPLD the length of power output
               required for each light
      CPLD: interface between analog and digital portions of dimmer rack; receives
               zero cross pulses and correlates them with the proper pulse to be outputted
               for each channel
      choke: slows the rise and fall of current to the lights for their protection
      light: theatrical light needed to be controlled (actually 12 of them)
Performance required: For each of the twelve channels, must smoothly dim theatrical
lights both on and off in a near-linear fashion, with no flickering and using a standard
theatrical light board for input.

Project test procedures: For each of the twelve channels, light intensity will be
measured for discrete levels indicated by the light board. The number of levels tested
will depend on the demarcations of the light board, but it will probably be around twenty.
Also for each channel, the response when the light is dimmed and brightened will be
qualitatively assessed for flickering or other unwanted effects. Each will be tested by
dimming the light instantaneously (blackout), in two or three seconds (fast fade), and in
ten seconds (slow fade). This procedure will be repeated similarly for taking the lights
from off to full on. Response times will be measured if any delays (due to the choke) are
detected, especially for the instantaneous fade and brightening.

Schedule: (weeks are indicated by their starting date, i.e. Monday’s date)
      2/15 – 3/1: Test parts of the dimmer rack; learn how it is put together and how it
                  works; pinpoint areas which need to be fixed. Concentrate on digital
                  section, since this seems to be the main cause of the product’s
                  problems. Concentrate on one or two channels
      3/8 – 3/29: Design and test solutions to problems that were found
      4/5:        Extend changes to all 12 channels; test channels as they are completed
      4/12:       Field test product: this is tech week for “On the Rocks,” so the
                  dimmer rack should be ready to use. If it does not operate correctly,
                  make necessary changes to have dimmer rack ready by opening night
                  (4/16)
      4/19:       Write final report. Write user’s guide to the dimmer rack to leave
                  with KCSA
      4/26:       Demonstrate dimmer rack. Prepare and give presentation

Parts: The hardware for the dimmer rack has already been acquired. No new parts are
known to be needed, although certain parts may need to be replaced or added. Those
parts will need to be determined during the course of the project.

Cost:
        Labor: ($50/hr.) X 2.5 X (100 hrs.) = $12,500
        Parts: $100 for assorted parts (wires, chips, unknown part needs)
        Total: $12,500 + $100 = $12,600

Test of engineering specifications: The microcontroller baud rate must be within 0.1%
of the baud rate of the light control board in order for the microcontroller to read the data
reliably. Demonstrate by measuring the baud rates with the logic analyzer.