Theatre Design & Technology - Oct 1972 - 28

Fig. 2. An apparent linear change to the human eye is an

The power circuit consists of lamps (the controlled

actual change following a square-law curve. Most manufacturers have standardized on this dimmer response because
it is recommended by the Illuminating Engineering Soci-

load), current transformer, reactor, thyristors, and circuit
breaker (Fig. 3). The current transformer senses any over-

ety.
New Dimmer
The new dimmer employs modern solid-state technology to improve the performance of the conventional
thyristor dimmer. Integrated circuits provide the required
close matching of resistors and transistors because the devices are made at one time on the same chip. Use of
sensing circuits and feedback loops adds the function of
voltage regulation. The dimmer is not merely line voltage
compensated, it actually senses true rms output voltage,
compares it with the control setting, and maintains the
desired output regardless of loading, line voltage, and tempe ratu reo

load condition and sends a signal into the control circuit.
The circuit breaker serves as an on/off switch and as backup overcurrent protection with fast all-magnetic trip. The
thyristors control lamp voltage by conducting or blocking
ac power at such points in the appl ied waveform as to
provide the desired rms voltage on the load side. Their
switching action must be carefully timed and regulated,
and that is the function of the blocks in the control logic
portion of the diagram.
The main function of the reactor is to prevent lamp
filament noise. A voltage rise time less than 300 to 400
microseconds causes an incandescent lamp's filament to
"sing"; the shorter the rise time, the louder lamps sing. We
design for a rise time of 800 microseconds under full load
conditions when phased back to a turn-on angle of 90
degrees. At 90 degrees, line voltage is switched on at its
peak instantaneous value, giving a worst-case condition.
Voltage rise time decreases as a dimmer is unloaded, so
full-load rise time is made considerably higher than the
minimum to prevent audio pickup into stage microphones. An adequate reactor causes approximately 5 volts
drop in dimmer output of full load, but the consequent
reduction of light output is negligible. Other reasons for
including the reactor are that it reduces radio-frequency
interference and limits thyristor di/dt.
The close response of the logic circuit made it possible
to build in the dynamic square-law response shown in Fig.
2, so no curve adjustment is needed and all dimmer out-

100
90
80
n.

70

::l

0

60

u...

50

=::l

'--

0

c

'-'

40

u
....

'-'

0..

30
20
10

Control Setting (S)

The new Iight dimmers are modu lar, made in several standard sizes
to supply different amounts of lamp wattage. Each has a circuit
breaker used as an on-off switch. Standardized cabinets hold as
many dimmers as needed.

28

2- The inherent relationships between lamp voltage, apparent light
output, and actual light output enable the new dimmer to electronically convert a linear control change to an apparent linear
change in light output. The apparent change is an actual change
following a square-law curve.

I]illL]

THEATRE DESIGN AND TECHNOLOGY

OCTOBER, 1972



Table of Contents for the Digital Edition of Theatre Design & Technology - Oct 1972

Contents
Theatre Design & Technology - Oct 1972 - 1
Theatre Design & Technology - Oct 1972 - 2
Theatre Design & Technology - Oct 1972 - 3
Theatre Design & Technology - Oct 1972 - Contents
Theatre Design & Technology - Oct 1972 - 5
Theatre Design & Technology - Oct 1972 - 6
Theatre Design & Technology - Oct 1972 - 7
Theatre Design & Technology - Oct 1972 - 8
Theatre Design & Technology - Oct 1972 - 9
Theatre Design & Technology - Oct 1972 - 10
Theatre Design & Technology - Oct 1972 - 11
Theatre Design & Technology - Oct 1972 - 12
Theatre Design & Technology - Oct 1972 - 13
Theatre Design & Technology - Oct 1972 - 14
Theatre Design & Technology - Oct 1972 - 15
Theatre Design & Technology - Oct 1972 - 16
Theatre Design & Technology - Oct 1972 - 17
Theatre Design & Technology - Oct 1972 - 18
Theatre Design & Technology - Oct 1972 - 19
Theatre Design & Technology - Oct 1972 - 20
Theatre Design & Technology - Oct 1972 - 21
Theatre Design & Technology - Oct 1972 - 22
Theatre Design & Technology - Oct 1972 - 23
Theatre Design & Technology - Oct 1972 - 24
Theatre Design & Technology - Oct 1972 - 25
Theatre Design & Technology - Oct 1972 - 26
Theatre Design & Technology - Oct 1972 - 27
Theatre Design & Technology - Oct 1972 - 28
Theatre Design & Technology - Oct 1972 - 29
Theatre Design & Technology - Oct 1972 - 30
Theatre Design & Technology - Oct 1972 - 31
Theatre Design & Technology - Oct 1972 - 32
Theatre Design & Technology - Oct 1972 - 33
Theatre Design & Technology - Oct 1972 - 34
Theatre Design & Technology - Oct 1972 - 35
Theatre Design & Technology - Oct 1972 - 36
Theatre Design & Technology - Oct 1972 - 37
Theatre Design & Technology - Oct 1972 - 38
Theatre Design & Technology - Oct 1972 - 39
Theatre Design & Technology - Oct 1972 - 40
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2020winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2020winter_public
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2019fall_public
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2019fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2019summer_public
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2019summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2019spring_public
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2019spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/usitt_techexpoguide_2019_public
http://www.nxtbook.com/nxtbooks/hickmanbrady/usitt_techexpoguide_2019
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2019winter_public
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2019winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2018fall_public
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2018fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2018summer_public
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2018summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2018spring_public
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2018spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2018winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2017fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2017fall_public
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2017summer_public
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2017summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2017spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2017spring_public
http://www.nxtbook.com/nxtbooks/hickmanbrady/usitt_techexpoguide_2017_public
http://www.nxtbook.com/nxtbooks/hickmanbrady/usitt_techexpoguide_2017
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2017winter_public
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2017winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2016fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2016summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2016spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2016spring_public
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2016winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2015fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2015summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2015spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2015winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2014fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2014summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2013winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2013summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2013fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2013spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2012winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2012fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2012summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2012spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2011winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2011fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2011summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2011spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2010winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2010fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2010summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2010spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2009winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2009fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2009summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2009spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2008winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2008fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2008summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2008spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2007winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2007fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2007summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2007spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2006winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2006fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2006summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2006spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2005winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2005fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2005summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2005spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2004winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2004fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2004summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2004spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2003winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2003fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2003summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2003spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2002winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2002fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2002summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2002spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2001winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2001fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2001summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2001spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2000winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2000fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2000summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_2000spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1999winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1999fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1999summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1999spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1998winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1998fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1998summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1998spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1997winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1997fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1997summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1997spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1996winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1996fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1996summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1996spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1995winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1995fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1995summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1995spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1994winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1994fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1994summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1994spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1993winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1993fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1993summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1993spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1992winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1992fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1992summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1992spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1991winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1991fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1991summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1991spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1990fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1990summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1990spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1989winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1989fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1989summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1989spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1988winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1988winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1988fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1988summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1988spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1987winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1987fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1987summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1987spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1986winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1986fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1986summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1986spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1985winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1985fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1985summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1985spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1984fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1984summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1984spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1983winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1983fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1983summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1983spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1982winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1982fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1982summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1982spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1981winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1981fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1981summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1981spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1980winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1980fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1980summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1980spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1979winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1979fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1979summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1979spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1978winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1978fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1978summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1978spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1977winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1977fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1977summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1977spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1976winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1976fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1976summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1976spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1975winter
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1975fall
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1975summer
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1975spring
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1974Dec
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1974Oct
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1974May
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1974Feb
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1973Dec
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1973Oct
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1973May
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1973Feb
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1972Dec
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1972Oct
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1972May
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1972Feb
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1971Dec
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1971Oct
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1971May
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1971Feb
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1970Dec
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1970Oct
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1970May
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1970Feb
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1969Dec
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1969Oct
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1969May
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1969Feb
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1968Dec
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1968Oct
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1968May
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1968Feb
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1967Dec
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1967Oct
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1967May
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1967Feb
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1966Dec
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1966Oct
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1966May
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1966Feb
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1965Dec
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1965Oct
http://www.nxtbook.com/nxtbooks/hickmanbrady/tdt_1965May
http://www.nxtbookMEDIA.com