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1947-48 Theatre Catalog, 6th Edition, Page 355 (341)

1947-48 Theatre Catalog, 6th Edition
1947-48 Theatre Catalog
1947-48 Theatre Catalog, 6th Edition, Page 355
Page 355

1947-48 Theatre Catalog, 6th Edition, Page 355

Tube-Type Rectifiers for Projection Arcs

Line of Models of Two, Four, or Six Tubes

Satisfy D.C. Requirement up to 80 Amperes

Conventional arc lamps employed'in motion-picture equipment require direct current-that is, current flowing constantly in one direction.

The sources of power usually available furnish alternating currentethat is, current that changes its direction of flow at regularly timed intervals. Two of these successive changes of direction constitute a complete cycle, and most power circuits have a change frequency of 60 cycles a second.

The conversion of alternating current to direct current is the business of the tube-type rectifier. Already in use for many years, tube-type rectifiers are, perhaps, the most economical in original equipment cost.


Simply speaking, the tube-type rectiiiers in most general use employ two or more rectifier tubes, in conjunction with a transformer. The rectifier tube functions as a kind of Hone-way valve;y permitting electric current to flow through it in only one direction. The transformer is used to step-down the line voltage to the voltage desired.

If one tube is connected in series with the secondary of the power transformer, only current flowing during half of each cycle will paSS through the tube, resulting in a direct pulsating current. This arrangement is called a half-wave rectis tier.

If two transformer secondarywindings are used, with a tube properly connected in each winding, one tube will pass cur rent fiowing in one direction during each cycle, and the other tube will pass current dowing in the opposite direction during each cycle. The direct pulsating current flowing from both tubes is then fed into a common circuit in such a way as to produce a steady direct current.

Tubes are limited in their current-carrying capacity. By connecting two or more tubes in parallel in each transformer winding, the amount of available direct current can be increased. Likewise, direct current from rectifiers operating on multiple-phase circuits may be added to provide for greater current requirements while equalizing the load on all phases of the circuit.


Incorporating the latest advances in the design of tube-type rectifiers with circuits already tried and proven through years of use, the RCA rectifier line includes features that make them outstanding in point of trouble-free and economical service. The unusually rugged electrical design utilizes ample masses of both steel and copper, providing low operating temperatures and long life.

Electrical circuits in these rectifiers are the results of years of experience and are designed around schematics also in use for many years, Where balanced



RCA Victor Division, Radio Corporation of America

tube loads are required, interphase of balancing transformers are used on all designs. While these are more expensive, they guarantee accurate tube bale ance.

Totally enclosed, rugged, toggling, rotary tap switches are used on all models of these rectifiers. The switches feature insulated dead shafts, continuous rotation in either direction, 12 pounds spring

pressure to the contact, and the use of completely non-carbonizing materials throughout.

Chimney draft ventilation on all models assures lower operating temperatures. Steel cases are streamlined and rugged, and attractively trimmed in chrome and red. Simplified mechanical construction permits ease of maintenance and servicing.

Optional equipment on RCA's rectiv fiers are amineters, which indicate the output amperage available.

THE TUBE-TYPE RECTIFIEBS, in the new line from the Radio Corporation of America. are housed in streamlined. rugged steel cases. attractiVely trimmed in chrome and red. The perforated metal top of the unit lifts off for easy accessibility to all parts and components. The control knob of the rotary tap switch will turn in either direction. Such rectitiers are said to be most economical in first cost.
1947-48 Theatre Catalog, 6th Edition, Page 355