The Secret Life of Machines (1988) s02e04 Episode Script
The Telephone
1 [Footsteps.]
[Jazzy music: 'The Russians Are Coming' - Val Bennett.]
[ring ring.]
[ring ring.]
Tim: Hello? It's a miracle of the age being able to pick up the phone and talk to somebody on the other side of the world.
But although this needs some very sophisticated electronics connecting the phone together the telephone itself has remained quite a simple gadget.
It's really just a set of push buttons, a couple of switches, a bit of electronics inside, a bell or a buzzer of some sort, and of course the handset.
Well, err, take the microphone out and give it to Rex.
The microphone and the earpiece are remarkably similar to those on the very first telephone invented over 100 years ago.
If I connect up the earpiece at this end and, er, Rex connects up the microphone at the other end I should be able to hear him.
Rex: Hallo, can you hear me Tim? Rex: (faintly through speaker) Can you hear me? Tim: Yes I can, it works very well.
This is too faint to work over long distances but the remarkable thing is that there's no battery in this circuit, it's just the microphone at one end, and the earpiece at the other.
In this programme I am going to look at how the telephone evolved from simple devices like this, to become the elaborate international system that it is today.
Rex (into microphone) Hallo Tim.
Can you hear me? It had been discovered in 1820 that any wire carrying electricity becomes slightly magnetic.
The effect was called electromagnetism.
Wrapping round, the wire round in a coil, greatly increases the effect.
[Clank.]
The extraordinary thing is that until 25 years ago most of the telephone system was worked by devices based on this simple effect.
The first use of the electromagnet though was for the teleGRAPH which in many ways was the forerunner of the telePHONE.
In its simplist form, you simply had a switch at one end Tim: Rex? [Quiet clicking noise.]
Tim: And a needle at the other.
This was made in lots of different varieties This is a, one for sending private messages.
This is a twin-needle one, and you could send all the different letters of the alphabet by a sort of code of different sequences of needle movements.
This is a replica of Samuel Morse's original apparatus it was quite elaborate at first.
You had to turn this handle to send the messages [squeaking.]
[cogs grinding and clanking.]
And the receiver printed the messages out on a strip of paper.
But the operators soon realised they could simply tap the message out and decipher the signal by simply listening to it.
and this was the origin of Morse code.
This was a system for unskilled operators you had one switch for each letter of the alphabet and if I press the 'R' and turn the handle The receiving station would have an identical instrument and the needle in the middle would go round to the same letter.
This is a more primitive version of the same thing.
Well, by 1860 the telegraph system had become big business all the major towns in Europe and America had a telegraph station.
the lines became so busy that, er, they had to develop a way of sending the messages at high speed.
So you had somebody printing the messages out on paper tape, and putting them into one of these machines that was a high speed sender [gearbox whine and rapid clicking noise.]
And at the other end, you had one of these machines which is an inking machine.
[clanking in recognisable morse code pattern.]
Not working at very high speed at the moment.
[clattering in morse.]
Okay, that's enough of that! Well this required a whole army of clerks which had to punch the messages out and then decipher them at the other end.
It was while trying to invent an improved version of this, that Alexander Graham Bell realised that it might be possible to send speech down the wires instead of simple pulses.
Bell's father was an ebullient teacher of elocution and speech therapy in Edinburgh.
Bell Snr: Graham, now listen to this poor woman.
Bell Snr: She has the most terrible problems with those labials.
Woman: Around the ragged Around the ragged Aaah! Bell Snr: Och and she's got a frightful lisp too.
Tim: However, Graham's two brothers then died of tuberculosis and his father then decided to emigrate to a healthier climate.
[bagpipes playing mournful tune.]
Mrs Bell: [sobbing.]
Bell Snr: And they had such lovely voices too.
Bell Snr: We'll do fine in America.
Woman: (Boston accent) Around the ragged rack Tim: Aged 25, Bell started teaching speech therapy himself in Boston.
[Woman drawls in background.]
At the same time he came up with his idea of a harmonic telegraph.
Recruiting a man from the local ironmonger's shop called Watson, He experimented sending several messages simultaneously at different tones, but nothing would make it work.
Bell: Och, it doesnae werk! On June 2nd 1875 though, he suddenly realised it could be modified to transmit speech.
[cymbal clash.]
Tim: Bell described what he'd done as transmitting voice-shaped currents.
Instead of the electromagnet just being on or off [clink.]
[clang.]
he was using it to vibrate a diaphragm and produce sounds.
Well if Rex now connects the electromagnet to my record player and we use the bass drum skin as the diaphragm erm you should be able to hear something.
[Bassey, indistinct 'The Russians Are Coming'.]
Tim: The magnet's vibrating the skin and this is moving the air reproducing the original sound.
This is one of Bell's original telephones.
You can see exactly the same arrangement with a diaphragm here, and electromagnet.
You listen in through the bottom here.
This is a modern telephone earpiece and you can see this has a metal diaphragm and the electromagnet is embedded in plastic down the bottom.
The principle is exactly the same Bell's patents made him a very rich man and he built an enormous mansion in Nova Scotia.
He grew rather portly and started experimenting with kites, twin-bearing sheep, iron lungs, hydrofoils, and all things.
He became completely fed up with the telephone, and wrote: "I have become so detached from it, I often wonder if I really did invent it, or was it just someone else I'd read about.
" Bell used a second receiver as his microphone.
It works exactly in reverse: When you speak near it, the diaphragm vibrates and creates a tiny electric current in the electromagnet.
I can show you this with a loudspeaker A loudspeaker is just a larger version of the same thing, really, with a paper cone as a diaphragm and an electromagnet underneath.
I connected it to a meter here and when I move the diaphragm [thudding on speaker cone.]
the meter measures the current.
Well now, if I connect it to a second speaker When I vibrate one speaker [thud thud thud.]
[rattle rattle rattle.]
the other one vibrates too.
This is how Rex was managing to talk to me at the beginning of the programme.
but it's not a very efficient process this, which is why Rex's voice was so faint.
and without any electronics, Bell's idea was much too faint to be of any practical use at all.
Rex: The first practical telephone used a completely different type of microphone.
This was patented by Thomas Edison, some two years after Bell.
Edison realised that if you apply a small amount of pressure to a lump of carbon, its resistance changed.
So he fitted a diaphragm to a piece of carbon.
This basic idea was greatly improved by a Rev.
Hunnings: he used a whole pile of carbon granules.
And we can reproduce this, quite easily, using a coffee jar top.
I've put a couple of bits of silver paper in here to form a contact and connecting up to a loudspeaker and a battery If I fill this with the granules, you'll hear it begin to crackle [loud amplified crackling noise.]
then fit a diaphragm, which is just a piece of plastic [more amplified crackling when Rex taps.]
If I cup my hands round it, and speak quite loudly, you should be able to hear (amplified through speaker) Bell's voice shaped currents coming out of the speaker.
And this type of microphone, in a refined version, was used in telephones right up until the late '70s.
[Doomful piano music.]
Tim: With Bell's receiver and Edison's microphone the telephone became a practical propoition.
[doomful music continues.]
At first the telephone companies had to stress its usefulness in emergencies because so few people had phones, they weren't much use for anything else.
This is part of a film made for a New York phone company in 1910.
[piano music continues.]
The company's efforts were obviously successful.
This is a pile of New York telephone directories a few years later.
This is one of Edison's first telephones you have to turn the handle all the time to hear anything through it.
It's called a chalk receiver.
This one's called the marriage, it's one of the (first) phones to combine Bell's receiver and Edison's microphone.
A lot of the early phones didn't have microphones as such, but they just had these wooden sounding boards which acted as the diaphragm you just had to speak somewhere near them.
This is the bell that called the attention of the operator.
This one's the horse collar phone that you put your head right in it [Tim mumbles into telephone.]
for private conversations.
One thing that most of these early phones had in common, was that the microphone was firmly fixed to the wall or a base.
And this stopped the carbon granules moving around and crackling too much.
The candlestick phone which came into fashion in the '20s, was a sort of compromise, although you could move the microphone around, it tended to keep the carbon granules at the same angle as you lifted it up.
Carbon microphones were gradually improved until they could be fitted into handsets.
And in fact many are still in use, crackling away.
[clunk.]
None of the early phones had dials, you simply asked the operator at the exchange to connect you to the number you wanted.
Early attempts at using male operators are said to have been unacceptable because they were too rude.
As the telephone system expanded more and more telephone operators were needed.
Operators: # With trunks and toll and telegrams, and all exchanges too.
# Just telephone and we will put you through! # Ring Arbour Corner Archway.
Ring Mayfair, Hop or Sloane.
# Ring anywhere, we're waiting on your phone.
# Do you want a little warning to make you get up in the morning? # Is your house on fire? # Do you want to send a wire? # Just lift up the receiver, # that's all you've got to do, to telephone, and we will put you through! The rapidly growing number of telephone operators increased the incentive for some sort of automatic switching system.
The answer was provided by the versatile electromagnet.
I still use electromagnetic switches called relays in a lot of the machines I make.
This is a nutcracker I made for an exhibition [whirring.]
[whirring and squeaking.]
The relays control the motor, it's actually quite useful to be able to see what's going on and they're actually quite reliable.
You can see one of their disadvantages though [Click whirrr.]
the sparks gradually erode the contacts away.
[buzzz click whirr.]
[whirrr.]
[thunk.]
The first automatic exchange was designed in desperation by an undertaker from Kansas city called Almon B Strowger in 1889 Strowger: Hmm, not enough people dying hereabouts.
Unless there's sommat funny going on Lets see, there's my arch-rival Mc Greedly.
Hmmm.
He seems mighty busy all of a sudden.
[horse cart rattles.]
There's Mrs McGreedly going to work at the telephone exchange.
Heeyyy! Telephone! McGreedly: So sorry to hear about your recent bereavement, but we do have a special offer this week.
six coffins for the three interior Strowger: That's It! She tells em who's dyin'! [scrabbling noise.]
So I make my own telephone exchange and cut out the third party.
This is a strowger selector made in the 1960s and it's still surprisingly similar.
There are two electromagnets, one makes this arm climb up [kerklunk kerklunk kerclunk.]
And the other ones makes it hunt across [kerklunk kerklunk kerklunk.]
And finally resets it Behind there's a large bank of contacts the arm sits in front.
This connects to the dial.
[clickclickclickclick.]
[whirrrrr.]
These are the clicks that you hear, when, err, whenever you dial a number.
[clickclickclickclick.]
[whirrrrr.]
[loud noisy environment.]
Many Strowger exchanges are still in use, this one's in Norwich.
although Strowger only imagined tiny exchanges with one contact for each subscriber his selectors were soon being connected together to make larger exchanges like this.
The engineers call the system affectionately, 'Click and Bang'.
Keeping it all working is quite an undertaking - the contacts tend to get dirty and make the lines noisy.
And the selectors need precise adjustment to work properly.
Also the mechanism gradually sheds tiny metal filings literally wearing itself out.
It's quite surprising it works at all.
[clicketyclicketyclickety.]
There quickly reaches a level where electromechanical devices become a bit absurd.
[clank thunk.]
This is a burglar enunciator built in the 1930s [crackle.]
Male voice on recording: These premises are being broken into, Po-lice, Scotland Yard.
Po-lice, Scotland Yard.
Po-lice, Scotland Yard.
This is a Burgot automatic burglar alarm.
Operating at: 'Jay' 'Eee' 'Ell' Tim: The solution was a whole new technology with no moving parts.
Which was based on a device invented for telephone exchange switching in 1947, the transistor.
It was credited to John Bardeen, Walter Brattain and William Shockley Bardeen was the mathematician who developed the theory.
Brattain was the practial experimentor who actually tried things out.
Shockley was the leader of the team, a visionary aloof from the day-to-day experiments.
He foresaw more advanced transistors developed years later, and finally disgraced himself with his campaign for bribing people with low IQs to be sterilised.
Shockley: Okay fella, you take the money and it won't hurt too much, okay? Fella: Ooooh! Tim: This is a modern transistor, a small amount of current in one side switches a much larger amount on the other side.
Here I've hooked up the high power side of a transistor to a car battery and a headlight.
And er, if I moisten my fingers I can now switch the transistor with the tiny amount of current passing through my body.
Just touching the low power side of the transistor is enough to switch the light on and off.
Solid state switching like this has enormous advantages there are no mechanical parts to wear out, and of course they're no contacts to spark across.
[click.]
[click.]
This dummy I made for a shopping centre had to work 12 hours a day.
And I worked out the "Spend, Spend, Spend" lights would be switching over 6 million times a year.
[pneumatic whooshing noise.]
Electromagnetic relays wouldn't have lasted long, but with transistors it should last for ages.
Transistors can actually switch millions of times a second, so fast that speech can be converted to a sort of code consisting of a very rapid string of on and off pulses.
this digital code has a better quality, just like the digital sound of compact discs.
And it also enables the sound to be processed by digital computers.
[callcentre noise.]
.
.
5698, 135, thank you, what's your number please? [clunk.]
[fileofax rattles.]
[clunk of removed plug.]
Today, computers are transforming telephone exchanges dramatically.
The operator switchboard, little changed from 1900, is being replaced by these computer keyboards.
The new digital exchange controll room looks just like an ordinary office.
The system's increadibly reliable failed connections have been reduced from 5% to 0.
01%.
So there's much less for the engineers to do.
Occasionally the computer does find a fault and tells them to change a panel.
[noise of lots of computers and associated aircon.]
The engineer first has to earth himself, to prevent any static electricity from damaging the chips.
The panel simply gets posted away to be repaired, the engineers say there is much less job satisfaction than with the old 'Click and Bang' system.
They all go home at 4:30pm and the exchange is then completely controlled from Cambridge until the next morning.
Like the digital exchange, modern telephones now use electronics.
This has enabled them to go back to Bell's elegant original idea of having an identical earpiece and microphone.
Rex (from speaker): Hallo! Can you hear me better now that it's amplified? Tim: It's now so loud that I hardly have to hold it to my ear at all and the sound quality's much better than Edison's crackly carbon microphone.
All thanks to this tiny transistor amplifier.
[Clunk.]
(tinny voice) It's surprising what you can do with transistor amplifiers you're listening to me now through a device that Rex gave me for Xmas last year When he takes it away from the glass [silence.]
[Clunk.]
Now he's put it back again, you can hear me quite clearly again.
Rex: This little acoustic probe can only pick up minute vibrations, and the window is acting as a diaphragm, exactly as a microphone.
It's got several serious uses, we can use to detect, er, a noise on a car engine so you can actually tell which tappet is making a noise, or which bearing has failed.
It's got lighthearted uses as well, erm, you can actually hear through a 9" wall far better than an upturned wine glass like grandmother used to use.
Erm, you can also as you see, listen through glass as if it wasn't there.
The other advantage of electronics is that it's also compact.
the latest chips and circuits are so small that there's room for a radio transmitter and receiver as well - the cordless phone.
There's even room for the very sophisticated electronics in a cellphone which automatically changes the frequency of its radio as it passes from one transmitter cell to the next.
Without the large bell and dial mechanism that used to fill the traditional designs, telephones have lost their distinctive, robust appearance.
The electronics will fit in almost any size or shape.
Perhaps the most striking thing about modern phones is their sheer quantity.
It wasn't long ago that it was extraordinary to have more than one phone in the house.
[50s music.]
Woman: Further more # A kitchen phone at hand when friends call up to chat a bit [music.]
[phone rings.]
# Hello, yes it is Mary.
How are you? Bye.
Caller: # They say your kitchen dazzles every eye! Woman: # A brand new sink, a built in ov-en # a new refrigerator, and a phone, # A kitchen phone! # A bright red phone! # I gotta go.
Goodbye goodbye goodbye! I'll call you later! [perky music.]
[music becomes slower, more romantic and calm.]
Tim: Today most homes have at least two phones, and often a cordless one as well.
And with a cellphone you can be in touch almost all the time, wherever you are.
The number of phonelines in Britain alone is growing by about a million a year.
[ring ring.]
It's all very convenient but the telephone does now seem to rule our lives.
[ring ring.]
it's almost impossible not to answer it when it rings.
[ring ring.]
[ring ring.]
[clank.]
Man: Oh! What! [water sloshing.]
Woman: Oh Help! Man: (wearily) Oh Dear! [ring.]
[ring.]
Woman: Hello? Woman: Wrong number! All: Oh! No! Tim: People talk about going away on holiday today to get away from the phone [Ring.]
Man: Hello Lofty All: "Oh No!" "Really!" Tim: I doubt whether Bell would have foreseen how dependent the world would become on his ingenious invention.
But I'm quite certain that he would never have guessed the elaborate lengths that some people would go to disguise the things.
[Jazzy music: 'Take 5' - Dave Brubeck.]
[Jazzy music: 'The Russians Are Coming' - Val Bennett.]
[ring ring.]
[ring ring.]
Tim: Hello? It's a miracle of the age being able to pick up the phone and talk to somebody on the other side of the world.
But although this needs some very sophisticated electronics connecting the phone together the telephone itself has remained quite a simple gadget.
It's really just a set of push buttons, a couple of switches, a bit of electronics inside, a bell or a buzzer of some sort, and of course the handset.
Well, err, take the microphone out and give it to Rex.
The microphone and the earpiece are remarkably similar to those on the very first telephone invented over 100 years ago.
If I connect up the earpiece at this end and, er, Rex connects up the microphone at the other end I should be able to hear him.
Rex: Hallo, can you hear me Tim? Rex: (faintly through speaker) Can you hear me? Tim: Yes I can, it works very well.
This is too faint to work over long distances but the remarkable thing is that there's no battery in this circuit, it's just the microphone at one end, and the earpiece at the other.
In this programme I am going to look at how the telephone evolved from simple devices like this, to become the elaborate international system that it is today.
Rex (into microphone) Hallo Tim.
Can you hear me? It had been discovered in 1820 that any wire carrying electricity becomes slightly magnetic.
The effect was called electromagnetism.
Wrapping round, the wire round in a coil, greatly increases the effect.
[Clank.]
The extraordinary thing is that until 25 years ago most of the telephone system was worked by devices based on this simple effect.
The first use of the electromagnet though was for the teleGRAPH which in many ways was the forerunner of the telePHONE.
In its simplist form, you simply had a switch at one end Tim: Rex? [Quiet clicking noise.]
Tim: And a needle at the other.
This was made in lots of different varieties This is a, one for sending private messages.
This is a twin-needle one, and you could send all the different letters of the alphabet by a sort of code of different sequences of needle movements.
This is a replica of Samuel Morse's original apparatus it was quite elaborate at first.
You had to turn this handle to send the messages [squeaking.]
[cogs grinding and clanking.]
And the receiver printed the messages out on a strip of paper.
But the operators soon realised they could simply tap the message out and decipher the signal by simply listening to it.
and this was the origin of Morse code.
This was a system for unskilled operators you had one switch for each letter of the alphabet and if I press the 'R' and turn the handle The receiving station would have an identical instrument and the needle in the middle would go round to the same letter.
This is a more primitive version of the same thing.
Well, by 1860 the telegraph system had become big business all the major towns in Europe and America had a telegraph station.
the lines became so busy that, er, they had to develop a way of sending the messages at high speed.
So you had somebody printing the messages out on paper tape, and putting them into one of these machines that was a high speed sender [gearbox whine and rapid clicking noise.]
And at the other end, you had one of these machines which is an inking machine.
[clanking in recognisable morse code pattern.]
Not working at very high speed at the moment.
[clattering in morse.]
Okay, that's enough of that! Well this required a whole army of clerks which had to punch the messages out and then decipher them at the other end.
It was while trying to invent an improved version of this, that Alexander Graham Bell realised that it might be possible to send speech down the wires instead of simple pulses.
Bell's father was an ebullient teacher of elocution and speech therapy in Edinburgh.
Bell Snr: Graham, now listen to this poor woman.
Bell Snr: She has the most terrible problems with those labials.
Woman: Around the ragged Around the ragged Aaah! Bell Snr: Och and she's got a frightful lisp too.
Tim: However, Graham's two brothers then died of tuberculosis and his father then decided to emigrate to a healthier climate.
[bagpipes playing mournful tune.]
Mrs Bell: [sobbing.]
Bell Snr: And they had such lovely voices too.
Bell Snr: We'll do fine in America.
Woman: (Boston accent) Around the ragged rack Tim: Aged 25, Bell started teaching speech therapy himself in Boston.
[Woman drawls in background.]
At the same time he came up with his idea of a harmonic telegraph.
Recruiting a man from the local ironmonger's shop called Watson, He experimented sending several messages simultaneously at different tones, but nothing would make it work.
Bell: Och, it doesnae werk! On June 2nd 1875 though, he suddenly realised it could be modified to transmit speech.
[cymbal clash.]
Tim: Bell described what he'd done as transmitting voice-shaped currents.
Instead of the electromagnet just being on or off [clink.]
[clang.]
he was using it to vibrate a diaphragm and produce sounds.
Well if Rex now connects the electromagnet to my record player and we use the bass drum skin as the diaphragm erm you should be able to hear something.
[Bassey, indistinct 'The Russians Are Coming'.]
Tim: The magnet's vibrating the skin and this is moving the air reproducing the original sound.
This is one of Bell's original telephones.
You can see exactly the same arrangement with a diaphragm here, and electromagnet.
You listen in through the bottom here.
This is a modern telephone earpiece and you can see this has a metal diaphragm and the electromagnet is embedded in plastic down the bottom.
The principle is exactly the same Bell's patents made him a very rich man and he built an enormous mansion in Nova Scotia.
He grew rather portly and started experimenting with kites, twin-bearing sheep, iron lungs, hydrofoils, and all things.
He became completely fed up with the telephone, and wrote: "I have become so detached from it, I often wonder if I really did invent it, or was it just someone else I'd read about.
" Bell used a second receiver as his microphone.
It works exactly in reverse: When you speak near it, the diaphragm vibrates and creates a tiny electric current in the electromagnet.
I can show you this with a loudspeaker A loudspeaker is just a larger version of the same thing, really, with a paper cone as a diaphragm and an electromagnet underneath.
I connected it to a meter here and when I move the diaphragm [thudding on speaker cone.]
the meter measures the current.
Well now, if I connect it to a second speaker When I vibrate one speaker [thud thud thud.]
[rattle rattle rattle.]
the other one vibrates too.
This is how Rex was managing to talk to me at the beginning of the programme.
but it's not a very efficient process this, which is why Rex's voice was so faint.
and without any electronics, Bell's idea was much too faint to be of any practical use at all.
Rex: The first practical telephone used a completely different type of microphone.
This was patented by Thomas Edison, some two years after Bell.
Edison realised that if you apply a small amount of pressure to a lump of carbon, its resistance changed.
So he fitted a diaphragm to a piece of carbon.
This basic idea was greatly improved by a Rev.
Hunnings: he used a whole pile of carbon granules.
And we can reproduce this, quite easily, using a coffee jar top.
I've put a couple of bits of silver paper in here to form a contact and connecting up to a loudspeaker and a battery If I fill this with the granules, you'll hear it begin to crackle [loud amplified crackling noise.]
then fit a diaphragm, which is just a piece of plastic [more amplified crackling when Rex taps.]
If I cup my hands round it, and speak quite loudly, you should be able to hear (amplified through speaker) Bell's voice shaped currents coming out of the speaker.
And this type of microphone, in a refined version, was used in telephones right up until the late '70s.
[Doomful piano music.]
Tim: With Bell's receiver and Edison's microphone the telephone became a practical propoition.
[doomful music continues.]
At first the telephone companies had to stress its usefulness in emergencies because so few people had phones, they weren't much use for anything else.
This is part of a film made for a New York phone company in 1910.
[piano music continues.]
The company's efforts were obviously successful.
This is a pile of New York telephone directories a few years later.
This is one of Edison's first telephones you have to turn the handle all the time to hear anything through it.
It's called a chalk receiver.
This one's called the marriage, it's one of the (first) phones to combine Bell's receiver and Edison's microphone.
A lot of the early phones didn't have microphones as such, but they just had these wooden sounding boards which acted as the diaphragm you just had to speak somewhere near them.
This is the bell that called the attention of the operator.
This one's the horse collar phone that you put your head right in it [Tim mumbles into telephone.]
for private conversations.
One thing that most of these early phones had in common, was that the microphone was firmly fixed to the wall or a base.
And this stopped the carbon granules moving around and crackling too much.
The candlestick phone which came into fashion in the '20s, was a sort of compromise, although you could move the microphone around, it tended to keep the carbon granules at the same angle as you lifted it up.
Carbon microphones were gradually improved until they could be fitted into handsets.
And in fact many are still in use, crackling away.
[clunk.]
None of the early phones had dials, you simply asked the operator at the exchange to connect you to the number you wanted.
Early attempts at using male operators are said to have been unacceptable because they were too rude.
As the telephone system expanded more and more telephone operators were needed.
Operators: # With trunks and toll and telegrams, and all exchanges too.
# Just telephone and we will put you through! # Ring Arbour Corner Archway.
Ring Mayfair, Hop or Sloane.
# Ring anywhere, we're waiting on your phone.
# Do you want a little warning to make you get up in the morning? # Is your house on fire? # Do you want to send a wire? # Just lift up the receiver, # that's all you've got to do, to telephone, and we will put you through! The rapidly growing number of telephone operators increased the incentive for some sort of automatic switching system.
The answer was provided by the versatile electromagnet.
I still use electromagnetic switches called relays in a lot of the machines I make.
This is a nutcracker I made for an exhibition [whirring.]
[whirring and squeaking.]
The relays control the motor, it's actually quite useful to be able to see what's going on and they're actually quite reliable.
You can see one of their disadvantages though [Click whirrr.]
the sparks gradually erode the contacts away.
[buzzz click whirr.]
[whirrr.]
[thunk.]
The first automatic exchange was designed in desperation by an undertaker from Kansas city called Almon B Strowger in 1889 Strowger: Hmm, not enough people dying hereabouts.
Unless there's sommat funny going on Lets see, there's my arch-rival Mc Greedly.
Hmmm.
He seems mighty busy all of a sudden.
[horse cart rattles.]
There's Mrs McGreedly going to work at the telephone exchange.
Heeyyy! Telephone! McGreedly: So sorry to hear about your recent bereavement, but we do have a special offer this week.
six coffins for the three interior Strowger: That's It! She tells em who's dyin'! [scrabbling noise.]
So I make my own telephone exchange and cut out the third party.
This is a strowger selector made in the 1960s and it's still surprisingly similar.
There are two electromagnets, one makes this arm climb up [kerklunk kerklunk kerclunk.]
And the other ones makes it hunt across [kerklunk kerklunk kerklunk.]
And finally resets it Behind there's a large bank of contacts the arm sits in front.
This connects to the dial.
[clickclickclickclick.]
[whirrrrr.]
These are the clicks that you hear, when, err, whenever you dial a number.
[clickclickclickclick.]
[whirrrrr.]
[loud noisy environment.]
Many Strowger exchanges are still in use, this one's in Norwich.
although Strowger only imagined tiny exchanges with one contact for each subscriber his selectors were soon being connected together to make larger exchanges like this.
The engineers call the system affectionately, 'Click and Bang'.
Keeping it all working is quite an undertaking - the contacts tend to get dirty and make the lines noisy.
And the selectors need precise adjustment to work properly.
Also the mechanism gradually sheds tiny metal filings literally wearing itself out.
It's quite surprising it works at all.
[clicketyclicketyclickety.]
There quickly reaches a level where electromechanical devices become a bit absurd.
[clank thunk.]
This is a burglar enunciator built in the 1930s [crackle.]
Male voice on recording: These premises are being broken into, Po-lice, Scotland Yard.
Po-lice, Scotland Yard.
Po-lice, Scotland Yard.
This is a Burgot automatic burglar alarm.
Operating at: 'Jay' 'Eee' 'Ell' Tim: The solution was a whole new technology with no moving parts.
Which was based on a device invented for telephone exchange switching in 1947, the transistor.
It was credited to John Bardeen, Walter Brattain and William Shockley Bardeen was the mathematician who developed the theory.
Brattain was the practial experimentor who actually tried things out.
Shockley was the leader of the team, a visionary aloof from the day-to-day experiments.
He foresaw more advanced transistors developed years later, and finally disgraced himself with his campaign for bribing people with low IQs to be sterilised.
Shockley: Okay fella, you take the money and it won't hurt too much, okay? Fella: Ooooh! Tim: This is a modern transistor, a small amount of current in one side switches a much larger amount on the other side.
Here I've hooked up the high power side of a transistor to a car battery and a headlight.
And er, if I moisten my fingers I can now switch the transistor with the tiny amount of current passing through my body.
Just touching the low power side of the transistor is enough to switch the light on and off.
Solid state switching like this has enormous advantages there are no mechanical parts to wear out, and of course they're no contacts to spark across.
[click.]
[click.]
This dummy I made for a shopping centre had to work 12 hours a day.
And I worked out the "Spend, Spend, Spend" lights would be switching over 6 million times a year.
[pneumatic whooshing noise.]
Electromagnetic relays wouldn't have lasted long, but with transistors it should last for ages.
Transistors can actually switch millions of times a second, so fast that speech can be converted to a sort of code consisting of a very rapid string of on and off pulses.
this digital code has a better quality, just like the digital sound of compact discs.
And it also enables the sound to be processed by digital computers.
[callcentre noise.]
.
.
5698, 135, thank you, what's your number please? [clunk.]
[fileofax rattles.]
[clunk of removed plug.]
Today, computers are transforming telephone exchanges dramatically.
The operator switchboard, little changed from 1900, is being replaced by these computer keyboards.
The new digital exchange controll room looks just like an ordinary office.
The system's increadibly reliable failed connections have been reduced from 5% to 0.
01%.
So there's much less for the engineers to do.
Occasionally the computer does find a fault and tells them to change a panel.
[noise of lots of computers and associated aircon.]
The engineer first has to earth himself, to prevent any static electricity from damaging the chips.
The panel simply gets posted away to be repaired, the engineers say there is much less job satisfaction than with the old 'Click and Bang' system.
They all go home at 4:30pm and the exchange is then completely controlled from Cambridge until the next morning.
Like the digital exchange, modern telephones now use electronics.
This has enabled them to go back to Bell's elegant original idea of having an identical earpiece and microphone.
Rex (from speaker): Hallo! Can you hear me better now that it's amplified? Tim: It's now so loud that I hardly have to hold it to my ear at all and the sound quality's much better than Edison's crackly carbon microphone.
All thanks to this tiny transistor amplifier.
[Clunk.]
(tinny voice) It's surprising what you can do with transistor amplifiers you're listening to me now through a device that Rex gave me for Xmas last year When he takes it away from the glass [silence.]
[Clunk.]
Now he's put it back again, you can hear me quite clearly again.
Rex: This little acoustic probe can only pick up minute vibrations, and the window is acting as a diaphragm, exactly as a microphone.
It's got several serious uses, we can use to detect, er, a noise on a car engine so you can actually tell which tappet is making a noise, or which bearing has failed.
It's got lighthearted uses as well, erm, you can actually hear through a 9" wall far better than an upturned wine glass like grandmother used to use.
Erm, you can also as you see, listen through glass as if it wasn't there.
The other advantage of electronics is that it's also compact.
the latest chips and circuits are so small that there's room for a radio transmitter and receiver as well - the cordless phone.
There's even room for the very sophisticated electronics in a cellphone which automatically changes the frequency of its radio as it passes from one transmitter cell to the next.
Without the large bell and dial mechanism that used to fill the traditional designs, telephones have lost their distinctive, robust appearance.
The electronics will fit in almost any size or shape.
Perhaps the most striking thing about modern phones is their sheer quantity.
It wasn't long ago that it was extraordinary to have more than one phone in the house.
[50s music.]
Woman: Further more # A kitchen phone at hand when friends call up to chat a bit [music.]
[phone rings.]
# Hello, yes it is Mary.
How are you? Bye.
Caller: # They say your kitchen dazzles every eye! Woman: # A brand new sink, a built in ov-en # a new refrigerator, and a phone, # A kitchen phone! # A bright red phone! # I gotta go.
Goodbye goodbye goodbye! I'll call you later! [perky music.]
[music becomes slower, more romantic and calm.]
Tim: Today most homes have at least two phones, and often a cordless one as well.
And with a cellphone you can be in touch almost all the time, wherever you are.
The number of phonelines in Britain alone is growing by about a million a year.
[ring ring.]
It's all very convenient but the telephone does now seem to rule our lives.
[ring ring.]
it's almost impossible not to answer it when it rings.
[ring ring.]
[ring ring.]
[clank.]
Man: Oh! What! [water sloshing.]
Woman: Oh Help! Man: (wearily) Oh Dear! [ring.]
[ring.]
Woman: Hello? Woman: Wrong number! All: Oh! No! Tim: People talk about going away on holiday today to get away from the phone [Ring.]
Man: Hello Lofty All: "Oh No!" "Really!" Tim: I doubt whether Bell would have foreseen how dependent the world would become on his ingenious invention.
But I'm quite certain that he would never have guessed the elaborate lengths that some people would go to disguise the things.
[Jazzy music: 'Take 5' - Dave Brubeck.]