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Page 6
PROJECTION ENGINEERING
from your light socket!
— for condenser microphones
— for sound'On'film
— for recording and reproduction
Webster-Chicago Style R-ll
High and Low Voltage
Power Unit
Here, for the first -rime, is a practical, compact power supply, fully dependable, that eliminates "A", "B", and "C" batteries, charging apparatus, and trouble. Every theatre, recording studio, and broadcasting station needs one. Low in cost, easy to install, nothing to maintain.
The Webster-Chicago Power Unit, operating from either 110 or 220 volt A.C., furnishes all necessary filament, plate, grid and polarizing potential current without noise or fluctuation. The output includes:
Filament supply variable from 2 volts at 60 m.a. to 5 volts at 2 amperes,
190 volts for photoelectric cell or microphone,
90 to 135 volts for pre-amplifier circuit,
0 to -8 volts grid bias.
The high voltages are rectified through a standard 280 type tube, the low voltage through a durable copper-oxide rectifier which will operate for years without attention. Output may be regulated precisely through efficient, noiseless resistors. An efficient filter system removes all audible A.C. hum.
Install a Webster-Chicago Power Unit and forget power supply troubles — permanently!
Write today for Bulletin 116
WEBSTER M CHICAGO
The WEBSTER Company
Sound Amplifiers for Every Purpose
854 Blackhawk St. Chicago, III.
T.
_ HE Group Subscription Plan for Projection Engineering enables a group of engineers, executives, projectionists or technicians to subscribe at one-half the yearly rate. ,
The regular individual rate is $2.00 a year. In groups of 4 or more the subscription rate is $1.00 a year. (In Canada and foreign countries $2.00.)
The engineering departments of hundreds of manufacturers and scores of the M. P. M. O. U. locals in the projection and allied industries have used this Group Plan extensively, in renewing their subscriptions to Projection Engineering.
Each subscriber should print his name and address clearly and state his occupation — whether an executive, engineer, department head, contractor, installation man, projectionist or technician, etc.
Remember this Group Plan when Your Subscription Expires
( Projection Engineering )
Bryan Davis Publishing Co., Inc.
52 Vanderbilt Ave.,
N. Y., N. Y.
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