Awesome Ad of the Month!
Half the fun of old magazines is old ads. Like this one, which
promises you Total Knowledge of home maintenance from a single
book. Mess up in a catastrophic way? Just use the knowledge from
the free second book to build a new house!Laboratories. It has eight two-way telephone channels that can also
serve as telegraph or facsimile channels. Bell is now using this type
of equipment in several civilian installations, such as the one linking
Catalina Island to the California mainland.
A similar system developed by International Telephone and
Telegraph is capable of accommodating eight broadcast channels
on a single frequency, with only one transmitting and one receiving
antenna. Such microsecond technique may provide economical
radio reception in hotels and institutions.
How do they split seconds into a million or more pieces? For
transmission and control it is done by means of pulse-generating
circuits. Some of these generate square or peaked waves directly,
while others start with a standard vacuum-tube oscillator producing
the conventional sine wave and distort it into a series of square-
shaped pulses. This is done by overloading the tubes, and is called
the brute-force method. Using crystal-control, such circuits can be
stabilized with microsecond accuracy.
For reception and measurement, cathode-ray oscilloscopes are
used. In a cathode-ray tube electrons fly out of the cathode and are
focused into a beam that makes a spot of light on a fluorescent
screen. Deflecting apparatus in the throat bends the beam when a
suitable voltage is applied. Amplitude (voltage or current) is
represented on the face of the tube by vertical distances, time by
horizontal distances. The voltage that produces the horizontal
movement is called a time base ant the circuit that produces the
voltage is called a sweep circuit. A cathode-ray ‘scope may have a
sweep of 20 inches per microsecond.
Accuracy depends largely on the frequency standards available.
The Bureau of Standards has a number of transmitters constantly
on the air to provide a check. Its primary frequency standards are
accurate to better than one part in ten million. Its broadcast time
signals are constantly compared with absolute time data from the U.
S. Naval Observatory. Some of its equipment will measure a rate of
change equivalent to one second in 50 years. This remarkable
accuracy can be plucked out of the air for nothing. ENDThink space-savers are bad? Imagine being forced to bolt part of a
spare wheel to your car, just to get home. Think people don’t use their
indicators enough? Imagine a light that says “Okay Pass” and when
you pass, it’s right into an oncoming truck. Innovations!
TOP 4: AUTO INNOVATIONS OF 1948
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