Theatre Design & Technology - Oct 1966 - 16

The literature of the theatrical field contains several excellent discussions of a philosophy of control systems
with considerable attention given to the relationship between the operator, manual and data storage sections of
the system. The pillar which supports all of this complex
circuitry and mechanism is the assumption that information
being given to the translator and power control results
in unique and singular response. This property of the
translator and power circuit is vital if the entire system
is not to be continuously set "by eye".

The basic apparatus of the test setup is shown in Figure 1. and the detail of the output instrumentation is
shown in Figure 2. The use of the differential voltmeter
provides a convenient and accurate method of measuring
small changes in output voltage. The tests of use time,
of the leading edge details, turn on misfire and minimum
load for stable firing were conducted with use of a high
resolution oscilloscope with a delayed sweep time base.
The input Iine voltage was continuously monitored throughout the test program except during the acoustical tests.

The package of electronics which we usually call a "dimmer" is in reality only the translator and power control
part of the system.

TEST SE TVP

It will be the intent of the remainder of this paper to report on the results of some preliminary tests on a number
(5) of American dimmer designs, paying attention to each
unit's performance with respect to its manufacturer's
specifications, the unit's performance relative to the other
designs tested, and to any absolute criteria that seem
appropriate.
Well, what are the test criteria for a dimmer} In its simplest form the criterion can be stated: "A dimmer should
do what it is commanded to do and nothing else."
Since such a statement is the idealized criterion for any
and all devices of any kind, it is clear that we will have
to callout certain attributes based on the particular
needs of the theatrical lighting field.
The ideal dimmer has been defined, in part, earlier in
this paper by the criterion of unique response to command - but that is not the complete picture. The unit
also must respond in a way which is useful to its operator and be free from spurious and undesirable side effects. As a work ing definition for what constitutes a dimmer we will say that a dimmer is a device for the control
of power. The type of dimmer under discussion is the
remote control type of unit which is essentially a remotely programmable power supply designed to accommodate the particular needs of incandescent lamp loads and
the constraints of theatrical usage.
Having defined the class of dimmers that is of interest,
the next step is the construction of a test program
which will measure various attributes of the device.
The preliminary test program contained the following elements:
A.

Output Voltage vs Load

B.

Output Voltage vs LIl1e voltage

C

MIOHHum load for stable operation

D.

Rise time of the waveform

E.

Detail of the leading edge tranSient

F.

rvllsflfe at turn on

Fig. 1:

Basic Apparatus of the Test Setup

D.C
OIFFEFHIAL

VOLTMETER

DC outpUl
0-10 voll

OSCILLOSCOPE

Fig. 2:

Detail of the Output Instrumentation

The test results can be viewed in a number of different
ways. Perhaps one of the most interesting is to compare
manufacturer's specifications and the measured results.
Figure 3 shows in a table format the specifications of the
five designs tested. (Test No. 5 was a retest of No.
made at the manufacturers requesl.)

G. Characteristic of the contraler (control curve)
H.

I.

Acoustic nOise produced at the dlOlmel

3

4

6

4.8V

6V

6V

6V

5V

MIN LOAD

75W

180W

200W

IW

OW

LOAD REG

6v

6V

6V

S

4V

170V

NS

<\COUStlC nOise produced by Ehe dimmer at lllE lamp

A sample dimmer was obtained from each of five leading
American manufaciUrers. Each manufacturer or his representative was allowed to adjust his unit for best performance. (Some units were factory adjusted and sealed.)
Each manufacturer was notified of the time of the testing
of his unit and was invited to be present during the test
procedure.
Four of the designs tested were 6 KW units. The fifth
was a 7 KW unit which was operated within a maximum
load of 6 KW.

16

2
MAX DROP

LINE
REG

(two )

NS

lWUNE

CURVE
ACOUSTIC
NOISE (LAMP)

tl85V

NONE

io

SQUARE

SQUARE

SQUARE

SQUARE

SQUARE

NONE

NONE

NS

NONE

NONE

NS

~

NOT SPECIFIED

Fig 3:

Tabular Specifications for Five Designs Tested

I US ITT I

THEATRE DESIGN AND TECHNOLOGY



Table of Contents for the Digital Edition of Theatre Design & Technology - Oct 1966

Contents
Theatre Design & Technology - Oct 1966 - 1
Theatre Design & Technology - Oct 1966 - 2
Theatre Design & Technology - Oct 1966 - 3
Theatre Design & Technology - Oct 1966 - Contents
Theatre Design & Technology - Oct 1966 - 5
Theatre Design & Technology - Oct 1966 - 6
Theatre Design & Technology - Oct 1966 - 7
Theatre Design & Technology - Oct 1966 - 8
Theatre Design & Technology - Oct 1966 - 9
Theatre Design & Technology - Oct 1966 - 10
Theatre Design & Technology - Oct 1966 - 11
Theatre Design & Technology - Oct 1966 - 12
Theatre Design & Technology - Oct 1966 - 13
Theatre Design & Technology - Oct 1966 - 14
Theatre Design & Technology - Oct 1966 - 15
Theatre Design & Technology - Oct 1966 - 16
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Theatre Design & Technology - Oct 1966 - 18
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