Sound Waves, Phonograph, Stylus, Piezoelectric & Magnetic Cartridges, Thermionic Emission, Vacuum Tube, PN-Junction, Transistor and Amplifier

Posted by PITHOCRATES - May 2nd, 2012

Technology 101

The First Phonographs used a Stylus attached to a Diaphragm to Vibrate the Air and a Horn for Amplification 

Sound is vibration.  Sound waves we hear are vibrations in the air.  A plucked guitar string vibrates.  It transfers that vibration to the soundboard on the guitar body.  The vibration of the soundboard vibrates the air inside the guitar body.  Amplifying it.  And shaping it.  Giving it a rich and resonant sound.  Creating music.  And we can reverse this process.  Taking these vibrations from the air.  And putting them into a piece of wax.  Via a vibrating needle.  Or stylus.  Cutting wavy grooves into wax.  And then we can even reverse this process.  By dragging a stylus through those same wavy groves.  Causing the stylus to vibrate.  And if we transfer those vibrations to the air we can hear those sound waves.  And listen to the music they make.

The first phonographs could reproduce sound.  But they didn’t sound very good.  The first phonographs were purely mechanical.  A stylus vibrated a diaphragm.  The diaphragm vibrated the air.  And a horn attached to that diaphragm was the only amplification.  Sort of like cupping your hands around your mouth when shouting.  Which reinforced and concentrated the sound waves.  Making them louder in the direction you were facing.  Which is how these early phonographs worked.  But the quality of the sound was terrible.  And played at only one volume.  Low.

Electric circuits changed the way we listen to music.  Because we could amplify those low volumes.  By changing the vibrations created from those wavy grooves into an electrical signal.  The first phonographs used a piezoelectric cartridge.  Which the stylus attached to.  The piezoelectric cartridge converted a mechanical pressure (the needle vibrating in the wavy groove) into electricity.  Later phonographs used a magnetic cartridge.  Which did the same thing only using a varying magnetic field.  The vibration of the needle moved a magnet or a coil through a magnetic field.  Thus inducing a current in a coil.  Then all you needed was an amplifier and a loudspeaker to make sweet music.

Small Changes in the Control Grid Voltage of a Vacuum Tube make Larger Changes in the Plate Voltage

The first amplifiers used vacuum tubes.  Things that once filled our televisions and stereo systems.  Back in the old days.  Up until about the Seventies.  A vacuum tube operated on the principle of thermionic emission.  Which basically means if you heat a metal filament it will ‘boil off’ electrons.  The basic vacuum tube used for amplification consisted of a cathode and an anode.  Or filament and plate.  And a control grid in between.  Sealed in, of course, a vacuum.  Creating the triode.  The cathode (filament) and anode (plate) created an electric field when connected to a large power source.  The cathode is negative.  And the anode is positive.  When negatively charged electrons are ‘boiled off’ of the cathode the positive anode attracts them.  The greater the heat the greater the thermionic emission.  And the greater the current flow from cathode to anode.  Unless we change the electric field to inhibit the flow of current.  Which is the purpose of the control grid.

Small changes in the control grid voltage will make changes in the large current flowing from cathode to anode.  That is, the larger current replicates the smaller signal applied to the control grid.  This allows the triode to take the low voltage from a phonograph cartridge and amplify it to a higher voltage with enough power to drive a loudspeaker.  Which is similar to diaphragm and horn on the first phonographs.  Only the amplified electric signal moves a lot more air.  And better materials and construction create a better quality sound.  Amplifiers with vacuum tubes make beautiful music.  High-end audio equipment still uses them to this day.  Including almost all electric guitar amps.  So if they have the highest quality why don’t we use them elsewhere?  Because of thermionic emission.  And the heat required to ‘boil off’ those electrons.

Vacuum tubes worked well when plugged into line power.  Such as a radio in a house.  But they don’t work well on batteries.  Because it takes a lot of electric power to heat those filaments.  And you need pretty big batteries to get that kind of electric power.  Like a car battery.  But even a car battery didn’t let you listen to music for long when parked with the engine off.  Because those tubes drained that battery pretty fast.  So there were limitations in using vacuum tubes.  They draw a lot of power.  Produce a lot of heat.  And tend to be pieces of furniture in your house because of their physical size.

Small Changes in the Base Current of a Transistor is Replicated in the Larger Collector-Emitter Current

The transistor changed that.  Making music more portable.  Thanks to semiconductors.  Material with special electric properties.  Based on the amount of electrons in the atoms making up this material.  Atoms with extra electrons make material with a negative charge (N-material).  Atoms missing some electrons make material with a positive charge (P-material).  When you put these materials together the N and the P attract each other.  Electrons cross the junction and fill in the holes that were missing electrons.  And the ‘holes’ cross the junction and fill in the spaces where there were excess electrons.  (When an electron moved, say, from right to left it made a hole and filled a hole.  It made a hole where it once was.  And it filled a hole where it now is.  So it looks like the hole moved from left to right when the electron moved from right to left.)  Neutralizing the N-material and the P-material.  But creating a charged region around the junction.  And it’s this electron flow and hole flow that make these PN junctions work.  When you add a third material you get a transistor.  Made up of three parts (NPN or PNP).  Emitter, base, and collector.

To get the electrons and holes flowing you start applying voltages across the junctions.  A large current will flow from the collector to the emitter.  Similar to the current flow in a tube from cathode to anode.  And a small base current will change that current flow.  Just like the control grid in a vacuum tube.  Small changes in the base current will make similar changes in the larger collector-emitter current.  Just like in a vacuum tube, the larger current replicates the smaller signal applied to the ‘control’.  Or base.  This allows the transistor to take the low-level signal from a phonograph cartridge and amplify it to a higher level.  Just like a vacuum tube.  Only with a fraction of the electric power.  Because there are no filaments to heat. 

Low power consumption and the small physical size allowed much smaller amplifiers.  And amplifiers that everyday batteries could power.  Creating new ways to listen to music.  From the pocket-size transistor radio.  To the bigger stereo boombox.  To the iPod.  Where the basic principle of how we listen to music hasn’t changed.  Just how we vibrate the air that makes that music has.

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Carbon, Carbon Cycle, Crude Oil, Petroleum, Hydrocarbons, Oil Refinery, Cracking, Sweet Crude, Sour Crude, Gasoline and Diesel Engines

Posted by PITHOCRATES - April 25th, 2012

Technology 101

Crude Oil is made from Long Chains of Carbon Atoms Bonded Together with a lot of Hydrogen Atoms Attached Along the Way

Carbon.  It’s everywhere.  And in everything.  Like all matter it cannot be created.  Or destroyed.  It just changes.  As it creates the circle of life.  The carbon cycle.  Plants and trees absorb carbon out of the atmosphere.  And converts it into biomass.  Into wood.  And into animal food.  Where the digestive system converts it into carbon-based living flesh and blood.  That exhales carbon.  Plants absorb carbon and release oxygen.  Plants can’t grow without carbon.  And we can’t breathe without plants growing.  Carbon is constantly changing.  But never created.  Or destroyed.  From diamonds to pencils.  From sugar to carbonated soda.  From plastics to human beings.  It’s everywhere.  And everything.  Why, it’s life itself.

Carbon is a time traveler.  Carbon that once traveled through the atmosphere disappeared millions of years ago.  Buried underneath the surface of the earth.  Under intense heat and pressure.  Plankton and algae and other biomasses decayed until there was almost nothing left but carbon atoms.  Long chains of carbon atoms.  Forming great, restless pools of black goo beneath the surface.   Waiting for the modern world to arrive.  Waiting for the internal combustion engine.  The jet engine.  And plastics.  When they could be reborn.  And see the light of day again.

Crude oil.  Petroleum.  Black gold.  Texas tea.  Hydrocarbons.  Long chains of carbon atoms bonded together with a lot of hydrogen atoms attached along the way.  In the ground they’re mostly long chains.  When we get them above ground we can break those chains into different lengths.  And create many different things.  C16H34 (hexadecane).  C9H20 (nonane).  C8H18 (octane).  C7H16 (heptane).  C5H12 (pentane).  C4H10 (butane).  C6H6 (benzene).  CH4 (methane).  Some of these you may be familiar with.  Some you may not.  Methane is a flammable gas.  Hydrocarbon chains from pentane to octane make gasoline.  Hydrocarbon chains from nonane to hexadecane make diesel fuel, kerosene and jet fuel.  Chains with more carbon atoms make lubricants.  Chains with even more carbon atoms make asphalt.  While chains with 4 carbon atoms or less make gases.  All these things made from the same black goo.  A true marvel of Mother Nature.  Or God.  Depending on your inclination.

Older Coastal Refineries make more Expensive Gasoline than the Newer Refineries due to the Availability of Sweet versus Sour Crude

Another great carbon-based product it bourbon.  Made from a corn sour mash.  We heat this and the alcohol in it boils off.  That is, we distill it.  We run this gas through a coiling coil and it condenses back into a liquid.  And after a few more steps we get delicious bourbon whiskey.  Distilleries give tours.  If you get a chance you should take one.  You won’t get to sample any of the distilled spirits (insurance reasons).  But you will get a feel for what an oil refinery is.

An oil refinery works on the same principles.  Boil and condense.  And cracking.  Cracking those long hydrocarbon chains apart into all those different chains.  Long and small.  Into liquids and gases.  Even solid lubricants and asphalt.  All made possible because of their different boiling points.  The gases having lower boiling points.  The solids having higher boiling points.  And the liquids having boiling points somewhere in between.

Refineries are complex processing plants.  Not only because of all those different hydrocarbon chains.  But because of the crude oil introduced to these plants.  For there is light sweet crude.  And heavier sour crude.  The difference being the additional stuff that we need to remove.  Such as sulfur.  An environmental problem.  So we have to remove as much of it as possible during the refining process to meet EPA standards.  The sweet crudes are lower in sulfur.  Making them the crude of choice.  But this has also been the most popular crude through the years.  So its resources are dwindling.  Making it more expensive.  As are all the products refined from it.  Especially gasoline.  The more sour crudes have higher sulfur content.  And require more refining steps to remove that sulfur.  Which means additional refinery equipment.  So the older refineries that were refining the light sweet crude can’t refine the heavier sour crudes.  Which is why the refineries along the coasts make more expensive gasoline than the newer ones in the interior refining the heavier sour crudes.  Due to the availability of sweet crude versus sour crude.

The Modern World is brought to us by a Complex Economy which is brought to us by Petroleum

One of the main uses of refined crude oil is fuel for internal combustion engines.  In particular, gasoline engines and diesel engines.  Which are very similar.  The difference being the mode of ignition.  And, of course, the fuel.  Gasoline engines compress an air-fuel mixture in the cylinder.  At the top of the compression stroke a spark plug ignites this highly compressed and heated mixture.  Sending the piston down.  If the combustion occurs too early it could place undo stresses on the piston connecting rods and the crank shaft.  By trying to send the piston down when it was coming up.  Causing a knocking sound.  Which is a bad sound to hear.  And if you hear it you should probably make sure you’re using the right gasoline.  If you are you need to have you car serviced.  Because continued knocking may break something.  And if it does your engine will work no more.  So this is where octane comes in the blending of gasoline.  It’s expensive.  But the more of it in gasoline the higher the compression you can have.  And the less knocking.  Which is its only purpose.  It doesn’t give you any more power.  The higher compression does.  Which the higher octane allows.  Using the higher octane gas in a standard compression engine won’t do anything but waste your hard earned money.

And speaking of higher compression engines, that brings us to diesel engines.  Which are similar to gasoline engines only they operate under a higher compression.  And don’t use spark plugs.  These engines compress air only.  Which allows the higher compression without pre-ignition.  At the top of their compression stroke a fuel injector squirts diesel fuel into the hot compressed air where it combusts on contact.  Diesel fuel has a higher energy content than gasoline.  Meaning for the same volume of fuel diesel can take you further than gasoline.  Which is why trucks, locomotives and ships use diesel.  But diesel tends to pollute more.  The smell and the soot kept diesel out of our cars for a long time.  As well as the difficulty of starting in cold climates.  Advanced computer controlled systems have helped, though, and we’re seeing more diesel used in cars now.

The modern world is brought to us by a complex economy.  Where goods and raw materials traverse the globe.  To feed our industries.  And to ship our finished goods.  Which we put on trucks, trains, ships and airplanes.  None of which would be possible without a portable, stable, energy-dense fuel.  That only refined petroleum can give us.  It’s better than animal power.  Water power.  Wind power.  Or steam power.  For there is nothing that we can use in our trucks, trains, ships and airplanes other than refined petroleum products today that wouldn’t be a step backwards in our modern world.  Nothing.  Making petroleum truly a marvel of Mother Nature.  Or God.  Depending on your inclination.

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