Back in the day,
Bell Telephone Labs' name was synonymous with cutting edge technology and
brainiac scientists and
engineers, similar to IBM (International Business Machines), Boeing, Chevrolet,
Westinghouse, and Hewlett Packard, amongst others. Bell Labs often ran full-page
promotions in electronics magazines like this one in a 1955 issue of Radio &
Television News that spotlighted a method they developed for inspecting relay
contacts without having to remove it from the circuit. Prior to solid state switches,
electromechanical relays did the circuit routing for the millions of calls crossing
the United States (prior to that, ladies sitting in front of switchboards used cables
and plugs to route calls manually). Those relays opened and closed thousands of
times each day, so they were subject to a lot of wear and tear. Bell Telephone invested
a lot of time and money into designing high quality relays that would stand up to
the usage. They also developed this method for inspecting the health of relays to
assist in improving the design.
Bell Telephone Laboratories Ad
He's "fingerprinting" a relay contact.
Bell Laboratories microchemists have perfected an ingenious new technique for
"fingerprinting" relay contacts, the tiny switches on which a dial telephone system
Using a portable test set, a chemist makes a plastic print of a contact. On-the-spot
examination of the print with a microscope and chemical reagents quickly reveals
the effects, if any, of arcing, friction, dust or corrosive vapor. While the chemist
studies the print, urgently needed contacts continue in service. Findings point
the way to improve relay performance.
This is another example of how Bell Telephone Laboratories research helps to
keep your telephone system the world's best.
Above, Bell Laboratories microchemist applies plastic disc in heated clamp to
relay contact. Imprint reveals contours of surface and picks up contaminants, if
any. Part of portable test set is shown on table. Contacts, shown in small sketches,
are of precious metal fused to base metal.
Preparing disc for microscopic examination. On-the-spot examination may reveal
acid, alkali, sulfur, soot or other polluting agents peculiar to an area.
A microscopic look at disc often provides lead to nature of trouble. Unlike actual
contact, print can be examined with transmitted light and high magnification.
Here the plastic disc has picked up microscopic lint that insulates contact,
stops current. (Picture enlarged 200 times.) Traces of contaminants are identified
in microgram quantities. Inert plastic resists test chemicals that would damage
Bell Telephone Laboratories
Improving telephone service for America provides careers for creative men in
scientific and technical fields
Posted July 15, 2020