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updated 6th October 2014
WHERE TO BEGIN? Chemistry and
Like other disciplines (music, math, art)
electronics is a language that is 'mastered' when the user is able to think
in that language. It is admittedtly hard to start at the beginning.
The text book addresses this by including simple chapters on Chemistry
and Physics, the most obvious being that conductors - what we know
as 'wire' - are the element metals (Copper, Silver Gold, Lead, Tin).
Somewhat less obvious - and less elemental - are the insulators wood,
glass, mica, air, rubber, plastic). Transistors, Diodes and LEDs
are semiconductors - unlike wire, they pass current in only
one direction and are made from the elements Silicon, Germainium,
Gallium, Aresenic and several others.
CHEMISTRY: how the elements are combined to make a device that gives
off a specific color when current is flowing through it
In the first two weeks we will explore
Multimeter. It will let us "see" the relationships of Volts (distance),
Amps / Current (tension), Power / Watts (heat) and Resistance (the bungee,
the light bulb) rated in Ohms. When an incandescent lamp is connected
to a power source - like a car's headlamp ato the battery - current flows,
the filament in the lamp gets so hot it glows. All connected, these
physical relationships produce tangible and measurable results. The
relationships so far are gnerally 'Linear,' and all relate correlate with
Take a Deep Breath...
Let's start with two simple
I had this idea to use a string
of lites to show the difference between Conventional Current Flow (plus
to minus) and Electron Flow (minus to plus). Here goes..
You might be wondering what
actually happens when you turn something on. Everything that matters
is MATTER and it's composed of atomic particles - protons, neutrons and
As the ancient geeks were
stumbling upon the basic building blocks - like generating and measuring
electricity - they had to "guess" when assigning POLARITY, like POSITIVE
and NEGATIVE. They had a fifty-fifty chance of getting it right (they didn't),
consequently, we have two ways at looking at how current flows. CONVENTIONAL
CURRENT flows from plus to minus - that's what the ancient geeks thought.
Later, once everybody had test equipment that could assist in deciphering
the laws of physics. It was determined that electrons were doing the moving
and shaking during the "current dance."
So, take a look at the sting
of lights. Electrons are in BLUE, moving from right-to-left. Holes are
in black and move from left to right.
I got this overview of "Holes"
In solid state physics, an electron hole
(usually referred to simply as a hole) is the absence of an electron from
the otherwise full valence band. A full (or nearly full) valence band is
present in semiconductors and insulators. The concept of a hole is essentially
a simple way to analyze the electronic transitions within the valence band.
Hole conduction can be explained by the
following analogy. Imagine a row of people seated in an auditorium, where
there are no spare chairs. Someone in the middle of the row wants to leave,
so he jumps over the back of the seat into an empty row, and walks out.
The empty row is analogous to the conduction band, and the person walking
out is analogous to a free electron.
Now imagine someone else comes along and
wants to sit down. The empty row has a poor view; so he does not want to
sit there. Instead, a person in the crowded row moves into the empty seat
the first person left behind. The empty seat moves one spot closer to the
edge and the person waiting to sit down. The next person follows, and the
next, et cetera. One could say that the empty seat moves towards the edge
of the row. Once the empty seat reaches the edge, the new person can sit
In the process everyone in the row has
moved along. If those people were negatively charged (like electrons),
this movement would constitute conduction. If the seats themselves were
positively charged, then only the vacant seat would be positive. This is
a very simple model of how hole conduction works.
BUILDING A CIRCUIT, ONE
COMPONENT AT A TIME
There are a handful of Electronic
Components that can be configured into basic building blocks - useful
circuits that must first be "turned-on" to be in a useful state.
The most obvious example, for our purposes, is an audio amplifier.
It is neither fully ON nor OFF, but "biased" to an in-between "static"
state state so it is then ready to be dynamically modulated by an AC (alternating
There are AC and DC power
sources (such as wall power and batteries), Passive Components (resistors,
capacitors, switches, lamps and fuses), Active Components (vacuum tubes,
transistors and Integrated Circuits or ICs, the latter being the result
of component miniaturization).
For Schematic Symbol Exercise
AC signals can be Audio,
Radio Frequency (RF) or Power. DC signals can be Power (from batteries
or power supplies), control or logic signals. In any electronic
circuit, DC is required to turn the active components on via passive components
that establish and "center" the operating paramters. The essence
of circuit design is for ALL components to operate within a safe "window,"
from the obvious - not too hot as to compromise longevity - and the less
tangible - not too "cold" as to be unpredictable.
For Basic Schematic Exercise
Circuits can be analyzed
in both the virtual and the real world, on "paper" and with test equipment,
respectively. There are a handful of formulae, such as Ohm's Law
and the Power Formula, that can be used to establish and analyze the operating
A digital multimeter can
be used to measure "Potential" (in Volts), Current (in Amperes), Resistance
(in Ohms) and Capactance (in Micro-farads). Its pedecessor was an
analog VOM (volt-ohm, milliamp meter), still in use today.
Prior to the VOM, meters
were application-specific - capable of measuring one quantity only (volts
or amps, for example). A Wheastone Bridge was used to measure resistance