The Basics of Electronics

by David Askew

Overview

This book recommended for education, for hobbyists, and for those that want to learn more about how electronics work? Then this book is for you. This book goes through the basic theory of topics such as DC and AC. It also covers electronic components, how they work and applications along with labs to experiment with, audio data and troubleshooting. The end of the book also contains several listings of suppliers of both electronic components and test equipment.

Product Details

ISBN-13:	9798895185711
Publisher:	WP Lighthouse
Publication date:	11/28/2024
Sold by:	Barnes & Noble
Format:	eBook
Pages:	62
File size:	2 MB

Read an Excerpt

CHAPTER 1

BASIC ELECTRONICS

Electronics can get into large calculations, but that is not the intent in this book.

Electronics consist of Protons, a positive charge, Electrons, a negative charge, and Neutrons, which are neutral.

Electronics theory says that electrons flow, however most electronic symbols show the flow going from positive to negative. Therefore this book will be based on Proton or Positive Voltage Flow. The following picture shows the positive side of the battery connected to the anode side of a diode and following the arrow to the cathode.

Electronics uses two types of voltage Direct Current known as DC and Alternating Current known as AC. Other signals used in electronics are RF radio frequency and Serial which consists of digital signals in a sequence.

Electronics uses several components. The following is just a list of a few of them. We will discuss most of these products in further chapters.

Resistor, capacitors, Diodes, coils, transformers, transistors, IC's, batteries, LED's, LCD display, switches, buttons, and connectors.

CHAPTER 2

METERS AND STANDARD MATERIAL

I am including this chapter because meters are used in several of the labs. There are several types of meters, as shown in figure 2. In the appendix are lists of vendors that can supply meters.

Let's first talk about the common features of meters. As different style meters can include a lot of different measurements.

Volts: All meters have AC and DC voltage scales.

Amps: All meters have AC and DC amp scales.

Ohms: All meters include a resistance scale known as ohms.

Other features found in some meters, capacitance test, diode test, continuity, transistor testing, inductance, DB decibels, and frequency.

One of the most important factors when using a meter is to plug the test lead in the correct connectors. Use the owner's manual for this information.

Some meters are auto scaling and some are manual select.

Manual select meters require setting the voltage, current or ohms based on a range from 0 to the highest value on the selector.

In figure 3, this meter has DC voltage scales of 2, 20, 200, and 1000 volts. The ohms scale has 200, 2k, 20k, 200k, 2m, and 20m. The current scales are 200 ma, 20ma/10A this is determined by which input terminal is being used, 2 ma and 200 µa.

Most meters require selecting AC or DC, either by the dial, or by a push button selection. Read the owner's manual for proper operation.

Auto scaling meters only require selecting the right format such as voltage, current, or ohms. These meters will require selecting AC or DC typically through a push button and then they go the full voltage or current or ohms range of the meter automatically. In figure 4, volts only has one setting, however current has 3 settings.

Meters have several connection terminals. Be sure to connect to the correct plug in terminal and set for the function being used. Let's discuss the different terminal inputs on the meter shown in figure 5. The far right terminal is for the positive lead when measuring volts, ohms, capacitance, frequency, and diode test. The next terminal from the right is the common terminal. This terminal is used as the negative terminal with volts, ohms, capacitance frequency, diode test, low current, and temperature. The next terminal from the right is used for low current and temperature. The far left terminal is used for high current up to 10 amps.

Some additional features of meters require using push buttons for sub selection. For example one of my meters when using the ohms scale you can push a button to select diode mode or a continuity sounder.

An accessory I highly recommend is a test lead set with clips. Some meters, however come with clips that slip over the end of the test lead. In the appendix is a list of vendors that can supply this material. Most meters come standard with probes only, but you will find it is hard to hold both probes on a circuit at the same time. Therefore the clips come in handy to make a connection to circuit.

STANDARD MATERIAL RECOMMENDED FOR LABS

The following lists either basic assemble your own lab unit or purchase a factory built lab unit. To basic build your own lab, use the following parts;

Test punch block and wire jumpers. You can buy kits of precut jumpers, or you can buy 20 gauge solid wires to make jumpers.

The following is a kit of a perf board with wire jumpers. In the appendix is a list of vendors that can supply this material.

POWER SUPPLY:

Some lab test units come complete with built in power supplies. You can purchase variable power supplies that can be set to 12 or 5 volts. These will be the most common voltages we will work with in the labs. Information on these power supplies can be found in the appendix.

ALREADY MANUFACTURED LAB UNIT:

Or you can build your own unit as I did with many common functions I use.

Another device needed in some of the labs will be a test signal generator. Note that some of the pre-made lab units have signal generators built in. You can purchase a scope unit that connects to a computer. These units typically have test generators built in. In the appendix is a list of vendors that supply test generators.

This is an example of wiring using a perf test board. The leads coming from the left are from the power supply and the leads going to the right go to the meter. Push the leads of the components into the holes on the perf board. The columns from top to bottom are connected together. The large space in the center of the board going left to right divides the columns so the bottom set of columns are separate from the top set of columns. As you can see the two black wires are in the same column connecting these two negatives together. Typically red is used for positive and black is used for negative.

CHAPTER 3

DC THEORY

When talking about DC we will talk about Voltage measured in Volts, Current, measured in Amps, Resistance, measured in Ohms, and Power measured in Watts.

DC power sources can be batteries, power supplies that convert AC outlet power to DC, generators and solar panels.

DC voltage has one direction of voltage flowing at a time. Figure 12 shows the positive side of the power source flowing through the diode. These devices will be talked about in later chapters.

LAB 1

Take a 12 volt power source and connect the positive end to the anode side of the diode. Secondly connect the positive lead of the meter to the cathode side of the diode. Lastly connect the negative lead of the meter to the negative side of the power supply. As shown in Figure 13. In the appendix is a list of vendors that can supply this material.

Select DC voltage on the meter. Make note the voltage reading

LAB 2

Now let's reverse the diode as shown in Figure 14. Connect the positive side of the power source to the cathode lead of the diode. Then connect the anode side of the diode to the meter plus lead. Lastly connect the negative meter lead to the negative side of the power source.

Select DC voltage on the meter. Make note the voltage reading You should get a zero voltage reading. This shows how polarity is important with DC voltage.

ANSWERS TO QUESTIONS

Lab1 Should be about 11.3 VDC

Lab2 Should be 0 VDC

CHAPTER 4

RESISTORS

The next chapter is about resistors. DC voltage and current can be controlled through resistors. Resistance is real important both in electronic circuit components and in wire. As wires have resistance to them. Resistors are used for voltage drop, current reduction, and end of line termination. In the appendix you will find a chart with wire size and resistance values.

As the word Resistance consist of Resist, Resistors create Voltage and current drops.

Let's work with resistor formulas known as Ohms Law. Later we will get into lab projects showing the results from your formulas.

The symbol for a fixed resistor is [??], symbol for a variable resistor [??]

Resistors come in many shapes and sizes. Shapes can be tubular, rectangular or surface mounted and variable resistors typically have a round base with a shaft.

The following are the different Ohms Law Formulas

(R) Stands for Ohms

(E) Stands for Volts

(I) Stands for Amps

(P) Stands for Watts

1K = 1,000

1M = 1,000,000

I=E/R is used to calculate current when you know the voltage and resistance.

E=I*R is used to calculate voltage when you know the current and resistance

R=E/I is used to calculate resistance when you know voltage and current.

P=I*E is used to calculate power when you know the voltage and current.

Note there are other variances of these formulas. For example if you want to calculate the power but you only know the voltage and resistance. Use this formula.

P=E*E/R

We will first talk about resistors in series. When resistors are in series the value adds as shown in the following example

R1+R2=R3

Now let's put real values to the resistors. I am going to use standard value resistors that are readily available through the references listed in the Appendix.

R1 = 1K and R2 = 2.2k If we series these resistors you add 1K + 2.2K

Question 1: What is the result? ___________

Now let's talk about how the resistance value reacts to DC voltage when voltage is fed through the two resistors the voltage is divided proportionately. Calculate the voltage value at the connecting point of the two resistors. To do this, use the formula R1/ (R1+R2). This is taking the fractional figure of R1 over the total resistance of R1 + R2.

Question 2: Now apply real values listed above. 1000/ (1000 + 2200) what is the result ___________ we will call this result A.

Question 3: Now we will multiply this value towards the power supply voltage. Example we will use 12 volts. If we take A*12 = B this will equal the voltage drop across R1, what is the result of B ___________.

Question 4: So to determine the voltage drop across R2, you will need to take the difference for 12-B = C what is the result of C ___________.

A handy tool is the resistor color code chart.

In the next lab we will use a 1000 ohm resistor the colors for this resistor are Brown, Black and Red, for the 2200 ohm resistor the colors are Red, Red, and Red. Note we are using the 4 band color code. Band 1 is the 1st value, band 2 is the 2nd value, and band 3 is the multiplier in 10's.

LAB 3

Reference Figure 17

Let's take a 12 volt power source connect the positive side of the power source to one end of the 1000 ohm resistor, then tie the other end of the 1000 ohm and one end of the 2200 ohm resistors together, then tie the other side of the 2200 ohm resistor to the negative side of the power supply. Now take the positive lead of your meter to the tie point of the two resistors, and connect the negative lead to the negative side of the power supply. Measure the voltage between the negative side of the power and the center point of the resistors. This value should be close to the value C calculated in the above formula. Note these values will not be exactly the same as your calculation, because most resistors have tolerance between 5 and 10 percent.

Note when doing any lab assignment be sure the power source is off while making connections.

Now let's calculate the current flowing through the two resistors. Note when resistors are in series the current will be the same through both resistors. Use the following formula

I = E/R now take the real values and insert them in the formula.

Question 5: I = 12/3200 what is the result. ___________

LAB 4

Now for a lab assignment, take and disconnect the positive side of the 12 volts and connect to the positive lead of you meter, be sure to use the right connection on your meter for current. Then tie the negative lead of the meter to R1. Connect R1 and R2 in series as shown in the figure 17. Then tie the other end of R2 to the negative side of the power supply. Be sure your meter is set to DC current, if not you can damage your meter. Note you should get a reading similar to you calculation. Note these values will not be exactly the same as your calculation because most resistors have tolerance between 5 and 10 percent.

Note when doing any lab assignment be sure the power source is off while making connections.

Now let's talk about parallel resistors. The formula for parallel resistors is R total = 1/ (1/R1 + 1/R2)

Question 6: Now let's apply real resistor values, we will use the 1K and 2.2K values. Used in the last lab and parallel them using the formula R total = 1/ (1/R1 +1/ R2) what is the total resistance ___________

Now let's calculate the total current through the circuit. Use the formula I = E/R and use the resistance value calculated in question 6.

Question 7: Value. ___________

Now let's calculate the current through each resistor. Use the formula I = E/R. Since the resistors are paralleled, the voltage is the same across both resistors.

Question 8: Now using this formula calculate the current through R1. ___________

Question 9: Then using the formula again calculate the current through R2.

LAB 5

Lab Connect one end of both resistors together then connect to the positive side of the power. Now connect the meter in series like we did in the previous lab through each resistor. Remove the meter from R1, connect the R1 resistor lead to the negative side of the power supply. Now move R2 from the negative side of the power and connect to the positive lead of the meter.

Note when doing any lab assignment be sure the power source is off while making connections.

Current for R1 ___________ You will need to set your meter to the mA scale. This should be close to the figure calculated in question 8.

Current for R2 ___________ You will need to set your meter to the mA scale. This should be close to the figure calculated in question 9.

LAB 6

Now tie both of the ends of the resistors that were separate together, and tie the current meter in series. What current, reading do you get. ___________ This should be close to the figure calculated in question 7.

Wire resistance Note I am not listing any lab on this topic because of shock and fire danger.

Wire has resistance and becomes important on length, based on the amount of current draw. Example are, power extension cords, and what you can plug in the end of the cord.

Let's take a 100ft 16 gauge extension cord. The resistance of 16 gauge wire is .004 ohms per Ft. per conductor. All power cables consist of at least 2 conductors, one called line or the hot lead, and one called neutral or the return lead. Note some cables have a third conductor for ground protection. So for calculating loss you need to double the resistance value. The formula would be 100 for the length, times .004 ohms per foot, times the two conductors. So the total resistance for the 100ft extension cord 100 * .004 * 2 this is .8 ohms. Now let's look at different devices connected to the cord. Let's start with a hedge trimmer, these typically draw 3.8 amps, let's use the ohms law formula E=I*R. E=3.8*.8 the result is approximately 3.04 volts drop, with this drop the hedge trimmer should still work correctly. Now we will calculate the amperage for a 1000 watt space heater. Using a modified version of the power formula I=P/E. So applying the 1000 watt heater with 120 VAC we get I=1000/120, the result is I =8.33 amps. Now with the wire resistance of .004 ohms per ft. per conductor, times 100ft, times 2 conductors we get .8 ohms. Now using E=I*R, we get E=8.33 *.8, the voltage drop will be approximately 6.664 volts. The end result of 120 minus 6.664 volts will end up with 113.336 volts.

Note I am not doing a lob on this because it is too dangerous dealing with 120 VAC if you are not certified to do this.

The following is an example's that would relate to the technology field.

An example involving a fire alarm signaling circuit with several signaling devices, may have too much voltage drop for the last device on the circuit to work properly, or a paging system having to many speakers and the speakers at the end of the line may be very week.

Let's calculate the loss for the fire alarm signaling circuit. A typical fire alarm Audio Visual device used as a strobe and sounder on a fire system draws .188 amps each. These devices are connected in parallel. Now let's say you have a long hall that will require 20 of these devices, and you start out using 16 gauge wire. Now take .188 amps time 20 devices you get 3.76 amps, and let's say the cable run from the fire panel to the last device is 300ft. As we discussed earlier 16 gauge wire has .004 ohms per ft. per conductor with the cable consisting of two conductors. We will multiply 300 * .004 *2 we get 2.4 ohms. Now let's calculate the voltage loss. E=I * R. 3.76 amps times 2.4 ohms we get 9.024 volt loss. Most fire alarm devices are 24 volts DC, so if we subtract 9.024 volts from 24 volts we get 14.976 volts. The specific device I picked has a minimal operating voltage, of 16 volts, so the devices towards the end of the run would not work properly. Now let's redo our design and use 14 gauge wires with a loss of .00252 ohms per ft. With a 300 ft. times .0025 *2 = 1.5 ohms:

Now with the Current of 3.76 time 1.5 ohms we get a voltage drop of 5.64. Now we subtract this from 24 volts we get 18.36 volts so the last device will be within the 16 volt limit.

(Continues…)

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Excerpted from "The Basics of Electronics"
by .
Copyright © 2018 David Askew.
Excerpted by permission of AuthorHouse.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
Excerpts are provided by Dial-A-Book Inc. solely for the personal use of visitors to this web site.

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Table of Contents

Chapter 1 Basic Electronics, 1,
Chapter 2 Meters and standard material, 2,
Chapter 3 DC Theory, 7,
Chapter 4 Resistors, 9,
Chapter 5 Oscilloscope, 17,
Chapter 6 AC voltage, 19,
Chapter 7 Capacitors, 21,
Chapter 8 Inductors and Transformers, 27,
Chapter 9 Other signals, 33,
Chapter 10 Diodes, 35,
Chapter 11 Switches, 39,
Chapter 12 Relays and solenoids, 42,
Chapter 13 Transistors, 45,
Chapter 14 Audio, 48,
Chapter 15 Data, 54,
Chapter 16 Trouble shooting, 57,
Appendix, 58,