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National Bureau of Standards

Library, E-01 Admin, BIdg./

JUN 2 3 1967 353

Connector for Saturated Standard Cells

J. J. BARTH
THE NATIONAL BUREAU OF STANDARDS

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NBS TECHNICAL NOTE 353

ISSUED April 21, 1967

CONNECTOR FOR SATURATED STANDARD CELLS

J. J. BARTH

Rad io Standards Laboratory

Institute for Basic Standards

National Bureau of Standards

Boulder , Colorado

NBS Technical Notes are designed to supplement the Bureau's regular publications program. They provide a means tor making available scientific data that are of transient or limited interest. Technical Notes may be

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For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C., 20402

Price: 10 cents.
Connector for Saturated Standard Cells

by

Joseph J. Barth

National Bureau of Standards

Boulder, Colorado

ABSTRACT

This paper describes a connector used for making electrical connections

to saturated standard cells in oil baths. The connector has at least three

advantages over other methods in common use. These advantages are

namely: (1) it does not generate thermoelectromotive forces; (2) it allows

cell racks to be placed close together in the bath; and (3) it is economical

to fabricate since it can be made from a common inside caliper.

Key Words: connector, electromotive force, oil baths, standard cells,

thermoelectric.

li
CONNECTOR FOR SATURATED STANDARD CELLS

Saturated standard cells, when used in temperature-controlled

oil baths, are mounted in racks with provisions made for electrical

connections.

For many years, most saturated standard cells were used in

racks utilizing mercury cups as the means for electrical contact.

About a decade ago, commercially produced cell racks, with

rigid copper contact posts, were introduced for use in oil baths as well as air baths, and today this type is used extensively. Several

methods of connecting to the copper posts of this type of rack have

been used, including spring clips, alligator clips, etc. In these

procedures there is danger of shorting the connections and thus destroying the cell. The possibility also exists that unwanted thermoelectromotive forces will be created by the dissimilar metal of the

clips. Additionally, the bulkiness of some of these connections

makes it necessary to maintain an appreciable distance between the

cell racks, which can seriously reduce the usable capacity of the bath.

A connector that has been designed for making these connections

is shown in Fig. 1. It is convenient to use, thermal free, and cannot accidentally short the cell connections. It is a special type of

connector in that it is designed to fit between the posts of the cell rack.

This feature allows the cell racks to be placed close together. Therefore, a bath of given size is able to accommodate more cells than might

be possible with the methods mentioned previously. The connector

is versatile as it can be used with different cell racks even though the

spacing between the connecting posts may vary appreciably. It is inexpensive and is easily fabricated from a common inside caliper of the

type used in the machine shop.
The connector (as shown in Fig. 2) is operated by depressing the

acrylic plastic grips (4) and when it is placed on the cell rack (10), an

outward pressure of the steel arms (5), made possible by the "C" spring

(1) and pivot pin (3), forces the acrylic plastic insulating blocks (7), with

special copper contact points (8), to fit against the inside of the cell rack

posts (9). Connecting wires are soldered to the contact points (6) and

inserted through holes (7) extending through and out of the top of the

insulating blocks. The maximum outward travel of the arms is controlled

by the screw stop (2).

The connector may be disassembled by outward pressure of the arms,

forcing the "C" spring to snap off. It may be reassembled in the reverse

manner.
Fig. 1 Photograph of connector mounted on standard-cell rack
Fig. 2 Construction detail of connector

GPO 835-006

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