Basic Electronics

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http://electronicstheory.com/COURSES/ELECTRONICS/e101-2.htm

The Law of Electromagnetic charges

Like charges repel, and unlike charges attract.

Valence Ring of an atom

The outermost orbital ring of ELECTRONS in an ATOM.

VOLTAGE:

A difference in electric potential existing between two charged bodies. Electrical equivilant of pressure. Also known as ELECTROMOTIVE FORCE or EMF, and IR DROP.

AMPLITUDE:

The magnitude of change in a varying quantity from it's zero value. Usually measured in Voltage, or deciBels, can denote volume.

Atom

The smallest particle of an element that shares the properties of that element. They consist of ELECTRONS, PROTONS, and NEUTRONS. Protons and Neutrons are grouped together in the center and constitute the Nucleus. The electrons orbit around the Nucleus.

Conductance

The ability of a substance to allow a liquid like movement of free electrons.

Conductor

(1)A body of material so constructed that it will carry an electric current. (2)A Wire.

Current

The liquid like movement of free electrons within a conductor. See Also FLOW

Cycle

One complete revolution of a generator, from 0o to 360o. One cycle is said to be one WAVELENGTH long, and takes one PERIOD in time to produce. All cycles can be measured in FREQUENCY, and AMPLITUDE.

Electron

A negatively charged particle which orbits the nucleus of an ATOM. Also called a netatron. Positive electrons, or Positrons also exist.

Element

A known chemical substance that cannot be divided into simpler substances by chemical means, and all atoms within it share the same atomic number.

Flow

The liquid like movement of free electrons within a conductor. Same as CURRENT.

Free Electron

Electrons which are not bound to an atom, but may move or be shared with other atoms within a substance.

Frequency

The number of complete sine wave cycles generated in one second. Frequency is measured in CYCLES PER SECOND (cps), PERIODS PER SECOND (pps) or more often HERTZ (Hz).

Gas

A physical state of matter in which molecules have free movement among themselves, diffuse readily, and expand in all directions indefinately. The vaporous state of a solid or gas. Gasses take the shape of their container, and flow smoothly.

Hertz

The unit of measurement for FREQUENCY. Synonymous with Cycles Per Second.

Inductance

The property of a circuit which opposes any change in the existing current, usually produced by a coil of wire, otherwise known as an INDUCTOR.

Induce

To produce by the influence of a magnetic or electric field. To convert electric energy magnetic energy, or magnetic energy into electric energy by proximity.

Induction

The creation of an electric current in a conductor by the proximity of a magnetic field to the conductor. The creation of a magnetic field by the flow of electric current in a conductor.

Inductor

A conductor, usually wound in a spiral or coil, which introduces (induces) a magnetic field into the surrounding atmosphere.

Insulator

A substance not easily given to CONDUCTING electric current. Insulators have very few FREE ELECTRONS.

Liquids

A physical state of matter in which molecules have free movement among themselves, but do not seperate as in gasses. The melted state of a solid. Liquids take the shape of their container, and flow smoothly.

Matter

everything that has weight and occupies space.

Molecule

The smallest partical in any substance that still retains the physical and chemical properties of that substance

Neutron

A particle found within the nucleus of an ATOM, which carries neither a positive nor a negative charge.

Nucleus

The center of an ATOM, made up of protons and neutrons.

Ohm

The constant unit of measurement for RESISTANCE. Symbolized by the Greek letter omega (W), it is the value of resistance through which a potential difference of one VOLT will maintain one AMPERE. Specifically defined as the resistance of a uniform column of mercury that is 106.3 cm long, with a weight of 14.4521 grams at a temperature of 0o C.

Period

The TIME (in seconds) which it takes to complete one CYCLE of an alternating wave.

Positron

A highly unstable positively charged particle with the same weight and mass as an electron. Their existance was predicted years before it could be proven.

Proton

A positively charged particle found within the nucleus of an ATOM.

Resistance

The opposition to the liquid like movement of free electrons within a conductor. Electrical friction. Reciprocal of CONDUCTANCE

Valence Ring

The outermost orbital ring of ELECTRONS in an ATOM.

Voltage

A difference in electric potential existing between two charged bodies. Electrical equivilant of pressure. Also known as ELECTROMOTIVE FORCE or EMF, and IR DROP.

Wavelength

The DISTANCE between points of corresponding phase between two consecutive cycles of a wave.
NOTE* It is a distance or length, as opposed to PERIOD, which is a time, and CYCLE, which is a 360o phase change of an alternating signal.

Electricity acts like which state of matter- - solid, liquid or gas?

Liquid It flows and has a measurable CURRENT . We can restrict its flow by adding electrical friction. We say that the restriction of electrical flow is called RESISTANCE and that a device which causes such RESISTANCE is called a RESISTOR . All materials, even the very best CONDUCTORS demonstrate a certain amount of RESISTANCE to electron flow.

How do we compare and measure the resistance of various materials?

in Ohms

Four factors that determine the resistance of a material

1. Type of Material -- copper less resistance than wood
2. Length The resistance of a material is directly proportional to its length. The longer the material is, the more resistance it has. This is because the electrons must flow through more material, and therefore meets more friction over the entire distance.
3. Cross Sectional Area
The resistance of a material is inversely proportional to the cross sectional area of the material. This means that the thicker the substance is across, the lower the resistance. This is because the larger the cross sectional area is, the less friction there is over a given length. (Picture in your mind, if you will, that a fire hose will pass more water than a garden hose, because the wider the pipe, the less resistance it has).
4. Temperature
In various types of materials, resistance can vary inversely or directly with the temperature. This is because of the chemical properties of the material. In Carbon, for instance, the resistance decreases as the temperature rises. So we say it varies inversely. In copper, however, the opposite is true, with the rise in temperature, we have a rise in the resistance.

Resistance is a form of _______ which can generate __________.

friction, heat

Voltage describes electrical _______.

pressure. Just as water pressure is the force in physics that pushes water through a pipe, VOLTAGE is the physical force which pushes electrons through a wire.

Three synonyms for voltage

1. Electromotive force (EMF)
2. IR Drop
3. Potential Difference

Current describes

the flow or movement of electrons

Current is measured in _____.

amperes.

Three ways to generate electricity:

1. Chemical
2. Magnetic
3. Transducer

What is a battery?

Batteries are produced using two dissimilar conductive materials into an acid ELECTROLYTE .

What is a dry cell battery made of?

The dry cell contains a carbon rod, which acts as the positive terminal, surrounded by a core consisting of manganese dioxide, zinc chloride, glycerin, carbon particles, and sawdust. Around this core is a chemical paste made up of an ammonium chloride solution in starch. A zinc can is then used as the container for the cell and also acts as the negative terminal.

The carbon rod reacts with the zinc casing via the pasty electrolyte. This creates a 1.5 Volt potential difference between the positive and negative terminals of the cell. It is not the electrolyte, but the electrodes themselves (the zinc and carbon) which determine the voltage of the cell. Therefore, no matter which electrolyte is chosen to be placed between the zinc and the carbon, the cell will still produce 1.5 Volts.

So how do we come up with a 9 Volt battery?

By placing cells in series, we can add the Voltages together. Two 1.5 Volt cells in series would produce a 3 Volt output. 3 would product 4.5 Volts. 6 would produce 9 Volts. When we place cells in series, we say that it is a BATTERY of cells.

LEAD-ACID type battery

the negative electrode is made up of pure lead and the positive electrode is a lead-peroxide combination. The electrolyte nominally used is a diluted sulfuric acid. A single lead-acid cell produces 2.1 Volts, but these batteries are commonly produced in either 6.3 or 12.6 Volts.

The first three SCHEMATIC SYMBOLS you will be introduced to are the lamp, battery and resistor.

...

What is a resistor?

Any device that causes electrical friction

What can the battery symbol signify?

Any direct current voltage

What does the battery symbol mean?

The lines represent the electrodes of a battery. Note that the SHORT line is always the NEGATIVE terminal, and the longer line is always the POSITIVE terminal.

What do resistors look like?

The top one is a ceramic coated " wirewound ", which, as its name implies, consists of a winding of wire, cut to a certain length to create a certain amount of resistance. The second is a carbon composite, and the third is a metal film or metal oxide, which has very tight resistance tolerances.Note that on wirewound resistors, the values are printed on the side, whereas the carbon and metal types have their values painted on as color coded bands around the resistor.

Resistor Color code 0 - 9

black - 0 brown - 1 red -2 orange -3 yellow - 4 green - 5 blue - 6 purple - 7 grey - 8 white - 9

How do you calculate resistance by color codes?

band A is first significant figure of component value (left side)
band B is the second significant figure
band C is the decimal multiplier
band D if present, indicates tolerance of value in percent (no color means 20%)

Calculating resistance

What about Ripe Golden Squash Now on a resister -- the fourth band?

We as people, are not perfect. Because of this, we make imperfect products. No resister is perfect. They are, however, all close to the value listed on them, plus or minus a certain amount. The amount of difference between their actual value, and the value listed on them should always fall within a certain tolerance. That tolerance is listed on the resistor, and is also designated by a colored band. Ripe Golden Squash Now (RGSN) corresponds with Red, Gold, Silver, None - the order of resistor tolerances in ascending order. Red = 2%, Gold=5%, Silver=10%, and No Band (None) = 20%.

Let's assume that you have a 1000 Ohm resistor. If it has a 10% tolerance, it can be off by 100 Ohms, and still be good (1000Ω +/- 100Ω). So it will be allowed to be anywhere from 1100 to 900 Ohms, and still be considered good. If a 1000 Ohm resistor has a SILVER tolerance band, and is only 920 Ohms, it is considered to be within tolerance, and is a good resistor. However, what if a 1000 Ohm resistor has a GOLD or RED tolerance band, and is only 920 Ohms,

it is OUT of acceptable tolerance, and is considered to be a bad resistor.

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