RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling
2 MB. Its primary purpose was to provide me with ready access to commonly needed
formulas and reference material while performing my work as an RF system and circuit
design engineer. The World Wide Web (Internet) was largely an unknown entity at
the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps
while tying up your telephone line, and a nice lady's voice announced "You've Got
Mail" when a new message arrived...
All trademarks, copyrights, patents, and other rights of ownership to images
and text used on the RF Cafe website are hereby acknowledged.
Wax nostalgic about and learn from the history of early electronics.
See articles from Radio-Electronics,
published 1930-1988. All copyrights hereby acknowledged.
Teenagers try to use a dial phone...
Someone sent me a link to a viral video of a group of teenagers (aka "Millennials") attempting
to use an old school dial type telephone. Two things are notable. #1: They do not remove
the handset from the cradle prior to dialing. #2: One of them asks whether it is necessary
to let the dial spin all the way back to rest before dialing the next number. It's really
not their fault since except for in dusty old places like my house, finding a dial phone
is difficult. Many historians have commented that two innovations most responsible for
America's greatness in the last century were the interstate highway system (for moving
goods) and the telephone system. Bell Telephone Labs engineers designed phones and all
the equipment that connected them to be simple, highly functional, robust, and to have
an incredibly high level of reliability. America's telephone system was the envy of the
world - note in movies into the 1970s where people making overseas calls were depicted
as having major difficulties with making and keeping connections. Take apart a vintage
dial telephone and you will be amazed at the simplicity of a device which had no active
components, yet could make and receive crystal clear calls from anywhere in the country.
Quiz: The two lines connected to the phone are called "tip" and "ring;" do you know the
origin of the terms?*
New Bell Telephone
New "500" telephone. It has already been introduced
on a limited scale and will be put in use as opportunity permits. in places where it
can serve best. Note new dial and 25 per cent lighter handset.
It adds miles to your voice
For years the telephone you know and use has done its job well - and still does. But
as America grows, more people are settling in suburban areas. Telephone lines must be
longer; more voice energy is needed to span the extra miles.
Engineers at Bell Telephone Laboratories have developed a new telephone which can
deliver a voice ten times more powerfully than before. Outlying points may now be served
without the installation of extra-heavy wires or special batteries on subscribers' premises.
For shorter distances, the job can be done with thinner wires than before. Thus thousands
of tons of copper and other strategic materials are being conserved.
The new telephone shows once again how Bell Telephone Laboratories keeps making telephony
better while the cost stays low.
Adjustable volume control on bottom of new telephone permits subscriber to set it
to ring as loudly or softly as he pleases. Ring is pleasant and harmonious, yet stands
Quick Facts on New Telephone
Transmitter is much more powerful, due largely to increased sound pressure at the
diaphragm and more efficient use of the carbon granules that turn sound waves into electrical
Light ring armature diaphragm receiver produces three times as much acoustic energy
for the same input power. It transmits more of the high frequencies.
Improved dial mechanism can send pulses over greater distances to operate switches
in dial exchange.
Built-in varistors equalize current, so voices don't get too loud close to telephone
Despite increased sensitivity of receiver, "clicks" are subdued by copper oxide varistor
which chops off peaks of current surges.
Bell Telephone Laboratories
Improving telephone service for America provides careers for creative men in scientific
and technical fields.
Quiz Answer: The
image to the right shows plugs of the sort used with
switchboards. The "tip" of the plug physically connected to the "tip" wire on the
phone, and the "ring" area connected to the "ring" wire.
Posted July 31, 2018
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