Under Construction December 1 2014
Seven Generations of Telephony
From POTS ( Plain Ordinary Telephone Systems) to the Internet
Alexander Graham Bell, The Beginning.
The following text was taken from Wikepidia :
Bell's patent 174,465, was issued to Bell on March 7, 1876, by the U.S. Patent Office. Bell's patent covered "the method of, and apparatus for, transmitting vocal or other sounds telegraphically ... by causing electrical undulations, similar in form to the vibrations of the air accompanying the said vocal or other sound" Bell returned to Boston the same day and the next day resumed work, drawing in his notebook a diagram similar to that in Gray's patent caveat.
On March 10, 1876, three days after his patent was issued, Bell succeeded in getting his telephone to work, using a liquid transmitter similar to Gray's design. Vibration of the diaphragm caused a needle to vibrate in the water, varying the electrical resistance in the circuit. When Bell spoke the famous sentence "Mr Watson—Come here—I want to see you" into the liquid transmitter, Watson, listening at the receiving end in an adjoining room, heard the words clearly
As a retired employee of BC Telephone Company, currently TELUS, I had the privilege to working in the telephone industry, when the first 5 generation were still used in the province of British Columbia. (BC Telephone never switched to the "Cross Bar" Dial exchange but went from the "Strowger Switching" dial directly to the "Analog Electronic exchange.)
In 1961 I was working in Port Hardy on the "Tropospheric Scatter System" A system with dual 10,000 watt transmitter from Port Hardy to Annete Island, Alaska ; with a repeater at Trutch Island.
During that time the telephone system used in Port Hardy was a Magneto system, which used "Crank" Telephone. Notice the little icons of the "Candle Stick" telephone, you see on the left of this web site, which is one of the telephones in my collection.
The town of Port hardy at that time only had 500 people. In order to call some one, not on our own 10 party line, we would give the crank a long turn and signal the operator, who was Mary Eddy, the wife of the Airport manager.
When Mary answered I would would say, Mary, do you know where Don is? ( Don McIntyre was my supervisor). And Mary would Almost always know where he was and connect me to him.
Those were the days of simple, friendly and fast communication with anyone who lived in town. No waiting, if it was urgent, Mary would simply add you to the party line so you could join the conversation.
This was also the year a 150 line Automatic Dial exchange was in installed in Port Hardy to cover, Port Hardy, Coal Harbour and the Port Hardy Airport. A strowger switching system was installed, which I will briefly explain in the introduction and in more detail under the section "Strowger Switching Dial"
The Seven Generation of Telephony
1. The Magneto Telephone System
Telephones used in the "Magneto" system.
2. Common Battery
3. The Strowger switch
Almon B. Strowger developed a system of automatic switching using an electromechanicalcal switch based around around electromagnets and pawls. In 1888 he took out a US Patent No. 447918 10/6/1891.
Automatic switching was first invented by Connolly & McTigthe in 1879, but strowger first used it.
In October 1891 the 'Strowger Automatic Telephone Exchange' was started.
The theory of the selector.
The selecetor start in the "Home" position and will move to the selected telephone depending on the number of "Pulses" send to the relay arm.
Picture of a "Strowger" switch.
4. Crossbar Dial
Figure a shows a diagram of a crossbar switch. Notice that cross point 101 is closed.
5. Analog Electronic Exchange
6. Digital Electronic Exchange
7. The Internet (VOIP)
Copyright Jacob Romeyn
Copyright Jacob Romeyn