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Welcome! This website allows you to
browse the subject of ELECTRONICS. If you are just starting the learning journey, I hope you'll make use of the simple nature and graphical content of this site. Feel free to look around. Don't worry -- there are no tests at the end of the day. If you would like to contact me regarding this site, email me at [email protected] John Adams - Author
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THEORY
Gain the basic understanding of electronic principles that you will be making use of later. This includes Ohm's Law, Circuit Theory, etc.
APPLY IT!
Putting the theory to work. This includes sections on how to solder, multimeters, and of course, PROJECTS!
COMPONENTS
Learn about various electronics components.
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Post your basic electronics related questions here for others to answer and read.
REFERENCE, DATA AND COOL TOOLS!
Resistor color code info, plenty of calculators, chart, electronics data and other cool tools! VERY POPULAR PAGE
BOOKS/MAGs
A list of books and magazines relating to the subject of electronics. Includes direct links to amazon.com for ordering online.
LECTRIC LINKS
A list of top-rated Electronics-related sites on the Web.
BASIC ELECTRONICS.CD INFO
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I have been an author in the electronics/computer industires for 5 years. This section is about myself as well as my theories of the Internet and Electronics.
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NOTES:
Beginners - I've visited nearly 2500 electronics related websites while researching my book, Howard W. Sams Internet Guide to the Electronics
Industry. There was a mysterious lack of electronics sites with beginners information. Most of them assumed you knew something about electronics already. Not so with this site. I want to take you through the complete basics in an attempt to give you a stronger base in electronics knowledge. Hopefully these pages will help. Thanks.
Browse - It is my belief that the subject of electronics should be first browsed and not taught. Most people get started into electronics (myself included) by
THEORY | LAST SECTION | CIRCUITS EXPLAINED | MAIN
Theory of Electronics
The following sections cover the basic principles,
ideas, concepts, laws, and formulas behind
electronics. Don’t be tempted to construct an
electronics-based career or hobby on a weak
foundation. Fully understanding these basic
theories will allow you to build that skyscraper
upon a firm foundation of concrete knowledge.
More sections will be added when ready.
CIRCUITS EXPLAINED: Find out what a circuit is composed of and the various types of circuits.
VOLTAGE, CURRENT & RESISTANCE EXPLAINED:
Learn the three basic measurements in electronics and what they really mean.
OHMS LAW EXPLAINED:
Please learn this one well. It is the basis of electronics. Your future learning depends on you knowing this one inside and out.
OHM'S CALCULATOR:
Simple Javascript Ohm's Calculator to help you determine circuit values.
RESISTOR COLOR CODES: Simple primer to help answer your basic resistor questions.
RESISTOR COLOR CALCULATOR: This is a COOL javascript resistor color codes calculator - even has a graphic of a resistor with adjustable color bands. Thanks to Danny Goodman for this treat. NOTE: You will need a Javascript enabled browser such as Netscape 3.0 or higher or MSIE 4.0. I don't think older versions of MSIE will work.
UNDERSTANDING AND CALCULATING SERIES, PARALLEL & COMBINATION CIRCUITS These are the basic rules and calculations for series, parallel and combination circuits -
- Just as important to learn well as Ohm's Law.
SCHEMATIC SYMBOLS: A list of common schematical symbols used in electronics.
THEORY | LAST SECTION | CIRCUITS EXPLAINED | MAIN
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©Copyright 1999 * John Adams
Last updated: April 1, 1999
Simple Circuit
If we break a circuit down to it's elementary blocks we get:
- A Power Source -- eg: battery
- A Path -- eg: a wire
- A Load -- eg: a lamp
- A Control -- eg: switch (Optional)
- An indicator -- eg: Meter (Optional)
Series Circuit A series circuit is one with all the loads in a row. Like links in a chain. There is only ONE path for the electricity to flow. If this circuit was a string of light bulbs, and one blew out, the remaining bulbs would turn off. There are specific properties to this circuit that will be described in another section.
NOTE: The squiggly lines in the diagram are the symbol for Resistors. The parallel lines are the symbol for a battery.
Parallel Circuit A parallel circuit is one that has two or more paths for the electricity to flow. In other words, the loads are parallel to each other. If the loads in this circuit were light bulbs and one blew out there is still current flowing to the others as they are still in a direct path from the negative to positive terminals of the battery. There are specific properties to a parallel circuit that will be described in another section.
Combination Circuit A combination circuit is one that has a "combination" of series and parallel paths for the electricity to flow. Its properties are a synthesis of the two. In this example, the parallel section of the circuit is like a sub-circuit and actually is part of an over-all series circuit.
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BACK
Understanding
& Calculating
Circuits
FORWARD Understanding
& Calculating
Parallel Circuits
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UNDERSTANDING & CALCULATING
SERIES CIRCUITS
BASIC RULES
A series circuit has certain characteristics and basic rules summized here:
- The same current flows through each part of a series circuit.
- The total resistance of a series circuit is equal to the sum of individual resistances.
- Voltage applied to a series circuit is equal to the sum of the individual voltage drops.
- The voltage drop across a resistor in a series circuit is directly proportional to the size of the resistor.
- If the circuit is broken at any point, no current will flow.
Let's look at each of these closer to gain an understanding of series circuits.
"1. The same current flows through each part of a series circuit."
In a series circuit, the amperage at any point in the circuit is the same. This will help in calculating circuit values using Ohm's Law.
You will notice from the diagram that 1 amp continually flows through the circuit. We will get to the calculations in a moment.
"2. The total resistance of a series circuit is equal to the sum of individual resistances."
V = 20 V
"Voltage Drops" Before we go any further let's define what a "voltage drop" is. A voltage drop is the amount the voltage lowers when crossing a component from the negative side to the positive side in a series circuit. If you placed a multimeter across a resistor, the voltage drop would be the amount of voltage you are reading. This is pictured with the red arrow in the diagram.
Say a battery is supplying 10 volts to a circuit of two resistors; each having a value of 5 Ohms. According to the previous rules we figure out the total resistance.:
RT = R1 + R2 = 5 = 5 = 10 Ohms Next we calculate the amperage in the circuit:
I = V / RT = 10V / 10 Ohms = 1 Amp
Now that we know the amperage for the circuit (remember the amperage does not change in a series circuit) we can calculate what the voltage drops across each resistor are using Ohm's Law (V = I x R).
V1 = 1A x 5 Ohms = 5 V V2 = 1A x 5 Ohms = 5 V
Now we get to the next rule.
"3. Voltage applied to a series circuit is equal to the sum of the individual voltage drops."
This simply means that the voltage drops have to add up to the voltage coming from the battey or batteries.
V total = V1 + V2 + V ...
In our example above, this means that 5V + 5V = 10V.
"4. The voltage drop across a resistor in a series circuit is directly proportional to the size of the resistor."
This is what we described in the Voltage Drop section above.
Voltage drop = Current times Resistor size.
"5. If the circuit is broken at any point, no current will flow." The best way to illustrate this is with a string of light bulbs. If one is burnt out, the whole thing stops working.
Now that you know these rules and calculations, try a few problems yourself using Ohm's Law to guide you. Just draw up a series circuit and leave a value out here and there. Once you understand this well go onto the next section about the properties of
Parallel Circuits.
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Sams Internet Guide to the Electronics
Industry*
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Book can be ordered from Howard W. Sams or bought in most bookstores.
- Spam or not, I have to make a living :-) Entire contents of this site are copyrighted -- Copyright 1997 * InfiNet-FX and John Adams Contact the Webmaster Last Updated: Nov 23, 1997
paths.
Let's look at each of these closer to gain an understanding of Parallel circuits.
Keep in mind that the diagrams below represent resistors and a battery. But they can just as easily be any resistance source such as a light bulb or power source such as a wall adaptor.
"1. A parallel circuit has two or more paths for current to flow through."
This is self explanatory. Simply remember that PARALLEL means two paths up to thousands of paths. The flow of electricity is divided between each according to the resistance along each route.
"2. Voltage is the same across each component of the parallel circuit."
You may remember from the last section that the voltage drops across a resistor in series. Not so with a parallel circuit. The voltage will be the same anywhere in the circuit.
"3. The sum of the currents through each path is equal to the total current that flows from the source."
If one path is drawing 1 amp and the other is drawing 1 amp then the total is 2 amps at the source. If there are 4 branches in this same 2 amp circuit, then one path may draw 1/4A (.25A), the next 1/4A (.25), the next 1/2A (.5A) and the last 1A. Don't worry, the next rule will show you how to figure this out. Simply remember for now that the branch currents must tally to equal the source current.
"4. You can find TOTAL RESISTANCE in a Parallel circuit with the following formula: 1/Rt = 1/R1 + 1/R2 + 1/R3 + ...
Before we get into the calculations, keep in mind what we said at the start of this section: "The total resistance of a parallel circuit is NOT equal to the sum of the resistors (like in a series circuit). That said, let's dig into the formula.
We will use a parallel circuit with 3 paths as an example (it can just as easily be 2, 4 or a 1000 resistors in parallel). The power source is providing 10 volts and the value of the resistors are 4 Ohm, 4 Ohm and 2 Ohm.
Let's summize this EXAMPLE for clarity:
Voltage = 10V R1 = 4 Ohm R2 = 4 Ohm R3 = 2 Ohm
Remember that "Rt" means Total resistance of the circuit. R1, R2, etc. are Resistor one, Resistor two, etc.
Before we move on to the last rule I want to show you how easy it is to calculate the amperage through each path using OHM'S LAW.
In the example we see a 10 and 20 ohm resistor in parallel with a 10 Volt source. First we figure out the total resistance of the circuit:
1/Rt = 1/10 + 1/ Rt = 6.67 Ohms
Now that you know this you can figure out the total amperage (It) using Ohm's Law:
I total (It) = 10V / 6.67 Ohms = 1.5 Amps
Therefore the total amperage between the two resistive paths must equal 1.5 Amps (Rule 3). Now we can figure out exactly what each path is pulling using Ohm's Law once more. Remember that the voltage is the same everywhere in a parallel circuit. So we know the voltage and the resistance:
I1 = 10V / 10 Ohm = 1 A I2 = 10V / 20 Ohm = .5 A
We figured the total amperage (It) previously, so now we can double check if the figures are correct:
I1 + I2 = It 1A + .5A = 1.5A - check
We will look at more calculations in future chapters.
"5. If one of the parallel paths is broken, current will continue to flow in all the other paths."
The best way to illustrate this is also with a string of light bulbs in paralallel. If one is burnt out, the others stay lit.
Now that you know these rules and calculations, try a few problems yourself using Ohm's Law to guide you. Just draw up a few parallel circuits and leave a value out here and there. Once you understand this we'll go onto the next section about the properties of
Combination Circuits.
TOP Main Page
Be sure to check out my book -- Howard W.
Sams Internet Guide to the Electronics
Industry*
Information
Submit new URLS
Comments
Book can be ordered from Howard W. Sams or bought in most bookstores.
- Spam or not, I have to make a living :-) Entire contents of this site are copyrighted -- Copyright 1997 * InfiNet-FX and John Adams Contact the Webmaster Last Updated: March 29, 1998
