Make: More Electronics: Journey Deep Into the World of Logic Chips, Amplifiers, Sensors, and Randomicity

783 Pages·2014·47.42 MB·English

by  Charles Platt

Make: More Electronics
Charles Platt
Dedication
In memory of my father, Maurice Platt, who showed me that it is a fine and valuable occupation to be
an engineer.
Acknowledgments
I discovered electronics when I was a teenager, in collaboration with my friends in high school. We
were nerds before the word existed. Patrick Fagg, Hugh Levinson, Graham Rogers, and John Witty
showed me some of the possibilities. Fifty years later, Graham kindly contributed a schematic to this
book.
Several decades after that, Mark Frauenfelder nudged me back into the habit of making things. Gareth
Branwyn facilitated Make: Electronics, and Brian Jepson enabled its sequel. They are three of the
best editors I have known, and they are also three of my favorite people. Most writers are not so
fortunate.
I am also grateful to Dale Dougherty for starting something that I never imagined could become so
important, and for welcoming me as a participant.
Fredrik Jansson provided advice and corrections while I was working on this project. His patience
and good humor have been very valuable to me.
Fact checking was also provided by Philipp Marek. Don’t blame Philipp or Fredrik if there are still
any errors in this book. Remember that it’s much easier for me to make an error than it is for someone
else to find it.
Circuits were built and tested by Frank Teng and A. Golin. I appreciate their help. I am also grateful
for the conscientious attention of Kara Ebrahim and Kristen Brown in the production department, and
proofreader Amanda Kersey.
Preface
This book picks up where my previous introductory guide, Make: Electronics, left off. Here you will
find topics that I did not explore in detail before, and other topics that were not covered at all
because I lacked sufficient space. You will also find that I go a little bit further into technicalities, to
enable a deeper understanding of the concepts. At the same time, I have tried to make “Learning by
Discovery” as much fun as possible.
A few of the ideas here have been discussed previously in Make magazine, in very different forms. I
always enjoy writing my regular column for Make, but the magazine format imposes strict limits on
the wordage and the number of illustrations. I can provide much more comprehensive coverage in this
book.
I have chosen not to deal with microcontrollers in much depth, because explaining their setup and
programming language(s) in sufficient detail would require too much space. Other books already
explain the various microcontroller chip families. I will suggest ways in which you can rebuild or
simplify the projects here by using a microcontroller, but I will leave you to pursue this further on
your own.
What You Need
Prior knowledge
You need a basic understanding of the topics that I covered in the previous book. These include
voltage, current, resistance, and Ohm’s law; capacitors, switches, transistors, and timers; soldering
and breadboarding; and a beginner’s knowledge of logic gates. Of course, you can also learn these
topics from other introductory guides. Generally I assume that you have read Make: Electronics or
a similar book, and you have a general memory of it, although you may have forgotten some
specifics. Therefore I will include a few quick reminders without repeating the general principles
to any significant extent.
Tools
I’m assuming you already own the following equipment, all of which was described in Make:
Electronics:
Multimeter
24-gauge multicolored hookup wire (25 feet of each color, in at least four colors)
Wire strippers
Pliers
Soldering iron and solder
Breadboard (the preferred type is described in the next section of the book.)
9V battery, or an AC adapter (with a DC output) that can deliver between 9VDC and 12VDC at
1A
Components
I have listed the components that you will need to build the projects. See Appendix B. That section
also recommends sources for mail-order.
Datasheets
I discussed datasheets in Make: Electronics, but I can’t overemphasize how important they are.
Please try to make a habit of checking them before you use a component that you haven’t
encountered before.
If you use any general search engine to find a part number, most likely you’ll see half a dozen sites
offering to show you the datasheet. These sites are organized for their profit, not for your
convenience. You will probably end up clicking repeatedly to see each individual page of the
datasheet, because the site owner wants to show you as many ads as possible.
You’ll save a lot of time by searching for the part number on the site of a supplier such as
http://www.mouser.com, at which point you will be able to click an icon to open the entire datasheet
as a multipage PDF document. This will be easier to view and print.
How to Use This Book
There are a few differences in style and organization between this book and the previous one. Also,
you need to know how to read the arithmetical notation that I have used.
Schematics
The schematics in Make: Electronics were drawn in an “old-school” style using semicircular
“jumps” wherever one wire crossed another without making a connection. I used this style because it
reduced the risk of making errors as a result of misinterpreting a circuit. In this book, I feel my
readers have had sufficient practice in reading schematics that it’s more important to conform with the
more modern style that is most commonly used in the rest of the world. See Figure 1 for clarification.
Figure 1. Top: In all the schematics in this book, conductors that make an electrical connection are joined with a black dot.
However, the configuration at far right is avoided because it looks too similar to a crossover where there is no connection.
Bottom: Conductors that cross one another without making a connection were shown in the style at left in Make: Electronics.
The style at right is more common, and is used in this book.
Also in Make: Electronics I used the European convention for eliminating decimal points in
component values. Thus, values such as 3.3K and 4.7K were expressed as 3K3 and 4K7. I still prefer
this style, because decimal points can become hard to discern in a poorly printed schematic.
However, some readers were confused by the European notation, so I have discontinued it in this
book.
Dimensions
Integrated circuit chips (and many other parts) all used to be equipped with wire legs, properly
known as “leads,” for insertion into holes in circuit boards. The leads on these “through-hole”
components were spaced at intervals of 0.1″, and the components were reasonably easy to grasp and
position with just your finger and thumb.
This idyllic vision of universal compatibility on a human scale was disrupted initially by an invasion
from the metric system. Some manufacturers moved from a pin spacing of 2.54mm (the equivalent of
0.1″) to 2mm as the standard, causing frustration for those of us using 0.1″ perforated board.
Millimeters popped up in other places, too. To take just one example, that most ubiquitous part, the
panel-mounted LED, is often 5mm in diameter. This is a fraction too big for a 3/16″ hole, but not
quite big enough to fit tightly in a 13/64″ hole.
Because this book is written and published in the United States, I generally use inches by preference.
You will find a conversion table between millimeters and fractions of an inch in Make: Electronics.
A much more significant problem is that the entire electronics industry has moved toward surface-
mount formats. Instead of a 0.1″ pin spacing, there are no pins at all, and a whole component is
typically no longer than 0.1″. To build a circuit from these parts, you really need tweezers, a
microscope, and a special soldering iron. It can be done, but personally I don’t find it enjoyable, and
you will not find any projects in this book that use surface-mount components.
Math
You won’t find a lot of mathematics here, but you do need to understand the simple arithmetic that’s
included.
I have chosen to use the style that’s common in programming languages. The * (asterisk) is used as a
multiplication symbol, while the / (forward slash) is used as a division symbol. Where some terms
are in parentheses, you deal with them first. Where parentheses are inside parentheses, you deal with
the innermost ones first. So, in this example:
A = 30 / (7 + (4 * 2) )
You would begin by multiplying 4 times 2, to get 8; then add 7, to get 15; then divide that into 30, to
get the value for A, which is 2.
Organization
Unlike the previous book, this one has a basically linear structure, mainly because it is more friendly
toward handheld devices, which cannot handle the amount of detail and variety scattered around a
double-page printed spread. I am hoping that you will progress through the book from beginning to
end, instead of dipping into it here and there.
The first project establishes concepts that will be used in the second project, and the second project
lays foundations for the third project. If you don’t follow this progression, you will run into some
problems.
You will find five types of sections identified in subheads:
Experiments
Hands-on work is the main thread of the book.
Quick Facts
After I’ve introduced a new concept, I will often summarize some take-home messages for easy
reference later.
Background
These are short detours from the main thread where I supply additional information that I think is
interesting or useful, even though it may not be strictly necessary for building a project. After a
brief description, I’ll leave you to pursue the topic on your own.
Make Even More
I don’t have space for thorough descriptions of all the possible construction projects, so I am
including short summaries of others that I have considered.
Warnings
Once in a while I will have to mention something that you should try to avoid doing, either for the
protection of the components that you are using, or to avoid an inconvenient error, or (rarely) to
protect yourself.
If Something Doesn’t Work
Usually there is only one way to build a circuit that works, while there are hundreds of ways to make
mistakes that will prevent it from working. Therefore the odds are against you, unless you proceed in
a really careful and methodical manner. I know how frustrating it is when the components just sit
there doing nothing, but if you have a problem, the following steps can usually help you to find the
most common errors:
1. Attach the black lead from your meter to the negative side of the power supply, and set the meter
to measure volts (DC volts, unless an experiment suggests otherwise). Make sure the power to
your circuit is switched on. Now touch the red probe from your meter to various locations in the
wiring, looking for erroneous voltages — or no voltage at all.
2. Check very carefully that all the jumper wires and component leads are exactly where they
should be on the breadboard.
Two types of breadboarding errors are extremely common: inserting a jumper wire one row higher or
one row lower than it should be, and placing two components or connections adjacent to each other
on a single row, forgetting that the conductor inside the breadboard will short them together. Figure 2
illustrates these common problems. Please check that you fully understand them!
In the upper photograph, the leads of the electrolytic capacitor are inserted between rows 13 and 15
of the breadboard, but because they are hidden from this perspective, it’s easy to place one end of a
blue jumper wire in row 14 by mistake. On the right, pin 5 of the chip is supposed to be grounded
through a ceramic capacitor, but because all the holes along each row of the breadboard are
connected internally, the capacitor is shorted out, and the chip is connected directly to ground. The
lower photograph shows the errors corrected.