Category: Science

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Simple LED Flasher using Transistors

Simple LED Flasher Project

I wanted to put together a simple two LED flasher circuit that would use the fewest parts and low power.  My first project of this type used the NE555 timer IC but besides the chip, it requires more power than what I would like to use.   Using a couple low-power NPN transistors, the circuit should be able to run for hours on a 9v battery.

The Circuit

I decided to use two 2N3904 transistors (a low power NPN transistor).  This design uses only 10 components but I added additional resistor to inline with the power source.  It could be removed and the other resistors adjusted to lower the power.

I used a free copy of LTSpice from Linear Technology to create the circuit (most SPICE packages do not have LED components for some reason) – you can download it here:  http://www.linear.com/designtools/software/ltspice.jsp

Which LED will light first?

The Breadboard

I assembled the circuit using a low cost breadboard I picked up at Fry’s Electronics.   Using a breadboard allowed me to play around with different components, especially the capacitors and resistors to tweak the flash rate and brightness.

Single LED Flasher

The simplest single LED Flasher circuit I have found uses a single transistor (NPN), 2 resistors and 1 capacitor.  This circuit uses the transistor as a Negistor using the NDR (negative differential resistance) effect.  The transitor will block current until the voltage threshold charging on C1 reach something close to 9v, at which point the voltage will become large enough to get the emitter-base junction to avelanche and drain the current through the LED.

Click here for the video:
http://jasonacox.com/images/IMG_2022.MOV

Reference

http://wild-bohemian.com/electronics/flasher.html

http://en.wikipedia.org/wiki/2N3904

http://www.linear.com/designtools/software/  (LTspice – Nice circuit design tool based on Spice)

http://jlnlabs.online.fr/cnr/negosc.htm

http://www.cappels.org/dproj/simplest_LED_flasher/Simplest_LED_Flasher_Circuit.html

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To Engineer is Human

To Engineer is Human: The Role of Failure in Successful Design by Henry Petroski

This is a great book to remind us of the purpose of engineering and the dangers we face when designing technical bridges (and physical ones) across the unknown.

Petroski wrote this in the early 80’s and the examples and illustrations are sometimes dated but still practical. I found the section on computers, “From slide rule to computer” to be particularly interesting.  His case still hold true for the faster/newer techno-driven culture of the 21st century.

We have come to be a society that is so quick to change that we have lost the benefits of one of mankind’s greatest tools–experience.   – Henry Petroski

Engineering is very dependant upon feedback for improvement.  The goal of providing a design solution for the lowest cost will mean that materials, processes and other costly items will be minimized to achieve the most economical/efficient solution.  Unfortunately, there are things that we do not know about (the trite, “we don’t know about what we don’t know” phrase comes to mind) that can be or become significant issues in the design.  The Tacoma Narrows Bridge is a great example of this.

Engineering attempts to introduce “safety factors” into the design model to cover for the unknowns but this can often be inadequate, as was the case of the walkway collapse at the Kansas City Hyatt Regency Hotel.

Failures, while unfortunate and often deadly, should also be opportunities for improvement.  Petroski argues that it is important that details of failures be broadcast to provide corrective feedback to all engineers so that future designs will build on these learnings.

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iWoz: Computer Geek to Cult Icon

This autobiography of Steve Wozniak is a delightful recount of the birth of the personal computer. 

Before cell phones that fit in the palm of your hand and slim laptops that fit snugly into briefcases, computers were like strange, alien vending machines. They had cryptic switches, punch cards and pages of encoded output. But in 1975, a young engineering wizard named Steve Wozniak had an idea: What if you combined computer circuitry with a regular typewriter keyboard and a video screen? The result was the first true personal computer, the Apple I, a widely affordable machine that anyone could understand and figure out how to use.

Wozniak’s life—before and after Apple—is a “home-brew” mix of brilliant discovery and adventure, as an engineer, a concert promoter, a fifth-grade teacher, a philanthropist, and an irrepressible prankster. From the invention of the first personal computer to the rise of Apple as an industry giant, iWoz presents a no-holds-barred, rollicking, firsthand account of the humanist inventor who ignited the computer revolution. 16 pages of illustrations.

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Six Not-So-Easy Pieces: Einstein’s Relativity, Symmetry, And Space-Time

This sequel to Richard Feynamn’s Six Easy Pieces grabs six more additional lectures from his famous three-volume series, Lectures on Physics.  In this book, Feynman unfolds the complexity of Relativity, Symmetry and Space-Time.   As is typical for his style, he makes these very complex subjects approachable, but then drives deeper to reveal the mathematics behind the mysteries.   The narrative and related equations are definitely geared toward math and science students. 

As is his genius, Richard Feynman often unpacks complex concepts through the use of practical analogies.  His description of curved space in Chapter 6 was one of my favorite sections (p. 112). 

Curved Space

In order to understand this idea of curved space in two dimensions you really have to appreciate the limited point of view of the character who lives in such a space.  Suppose we imagine a bug with no eyes who lives on a plane, as show in Figure 6-1.  He can move only on the plane, and he has no way of knowing that there is any way to discover any “outside world.” (He hasn’t got your imagination.)  We are, of course, going to argue by analogy.  We live in a three-dimensional world, and we don’t have any imagination about going off our three-dimensional world in a new direction; so we have to think the thing out by analogy.  It is as though we were bugs living on a plane, and there was a space in another direction.  That’s way we will first work with the bug, remembering that he must live on his surface and can’t get out.

As another example of a bug living in two dimensions, let’s imagine one who lives on a sphere.  We imagine that he can walk around on the surface of the sphere, as in Figure 6-2, but that he can’t look “up,” or “down,” or “out.”

Now we want to consider still a third kind of creature.  He is also a bug like the others, and also lives on a plane, as our first bug did, but this time the plane is peculiar.  The temperature is different at different places.  Also, the bug and any rules he uses are all made of the same material which expands when it is heated.  Whenever he puts a ruler somewhere to measure something the ruler expands immediately to the proper length for the temperature at that place.  Whenever he puts any object–himself, a ruler, a triangle, or anything–the thing stretches itself because of the thermal expansion. 

Feynman uses this constructed analogy to explain how the bug would get different measurements in each of these “worlds.”  The bug is able to determine what type of world it lives in based on the measurements.  It is interesting to see through his example that the bug on the sphere experiences the same measurements as the bug on the temperature varying hotplate (both can measure a triangle with an angle-sum of 270 degrees where the bug in the plane would see a maximum sum of 180 degrees).  Scientist speculate on the “space” curvature of the universe by conducting experiments.  So far, it is inconclusive.

In this book, Feynman also covers a refresher course on Vectors (Ch. 1), discusses the Symmetry in Physical Laws (Ch. 2), does a detailed analysis of The Special Theory of Relativity (Ch. 3), Relativistic Energy and Momentum (Ch. 4), Space-Time (Ch. 5), and Curved Space (Ch. 6).

Realativity

The Special Theory of Realativity (p. 49) is a facinating approach to motion that for over 200 years was ruled by equations developed by Isaac Newton.   In Newton’s Second Law, 

which is the same as F=ma (where a is acceleration or the time derivative of velocity, dv/dt), the assumption is that mass (m) is a constant.  Einstein corrected this formula with his theory by saying that mass has the changing value,

where mo is the “rest mass” of a body when it is not moving and c is the speed of light (186,000 mi/s or 3×10^5 km/s).

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Faster than the Speed of Light

Dr. João Magueijo presents a theory that allows for variable speed of light (VSL).   This is a rather controversial subject as it deals with a value in physics that has traditionally been constant (c, the value of the speed of light, 186,000 mps or 300,000 kps).  The speed of light is the underpinnings of Einstein’s theories of special relativity, as seen in the famous E=mc² equation.

The Book

While dealing very little with the science of theory itself, João does provide a very entertaining look at the often painful, slow and bureaucratic scientific process.  He spends considerable time presenting the histories and struggles of scientist like Einstein as well as his colleagues.  These narrative backdrops are used to provide contrast and similarities to his own scientific speculation.  These also provide the basis for the bipolar challanges against and support for VSL.

The Theory

João proposes that the speed of light is dependant upon energy or space-time.  He postulates that during the moment of creation, the high energy big bang of those intial moments could well increase the speed at which light travels by sixty orders of magnitude (that is 1 with 60 zeros).  This could explain the horizon problem of cosmology and propose an alternative to cosmic inflation.  This would reveal itself near black holes or cosmic strings.

The Scientist

Dr. João Magueijo received his doctorate from Cambridge, has been a faculty member at Princeton and Cambridge, and is currently a professor at Imperial College, London.   A lecture from João can be found here: http://forum.wgbh.org/wgbh/forum.php?lecture_id=3195

João writes, “we do not notice energy, but only variations in energy.”  He concludes the book by saying, “It’s difficult to sum up where VSL stands, as I finish this book… VSL is now an umbrella for many different theories.”

Links

VSL: http://en.wikipedia.org/wiki/Variable_speed_of_light
Speed of LIght: http://en.wikipedia.org/wiki/Speed_of_light

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Robotics

The LEGO mindstorm robotics kit is a popular programmable controller that can allow kids and adults alike to enter the world of robotics.  I am currently playing with a few free software programs that my friend found that let you simulate virtual robots, including the mindstorm.

LEGO Mindstorm

LEGO Digital Designer – Just for fun, build something!

Microsoft Robotics Developer Studio – This allows you to model a virtual robot and world, complete with controls to maneuver your robo-friend.

Modeling Programs we are investigating to see if they can be used to construct virtual robots or the worlds they live in:  Wings3d, Silo3d, Blender3d

Mindstorm blog:
http://thenxtstep.blogspot.com/

 

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Richard Feynman

Richard Feynman is Nobel prize winning physicist and famous communicator.  I put together a collection of YouTube Feynman videos: 

Transcript:

I have approximate answers and possible beliefs about different things, but I’m not too sure of anything. The many things I don’t know anything about, such as whether it means anything to ask why we’re here and what the question might mean, I might think about a little, but if I can’t figure it out, I go into something out. I don’t have to know an answer, and I don’t feel frightened by not knowing things. Being lost in the mysterious universe without having any purpose is the way it really is, as far as I can tell. Possibly, it doesn’t frighten.

I have a friend who’s an artist, and sometimes taking a view which I don’t agree with very well. He holds up a flower and says, “Look how beautiful it is,” and I’ll agree, but he says, “You see as I, as an artist, can see how beautiful this is, but you, as a scientist, take it all apart and it becomes a dull thing.” I think that he’s kind of nutty first of all. The beauty that he sees is available to other people and to me too, although I may not be as refined as he is. I can’t appreciate the beauty of the flower at the same time as I see much more about the flower than he sees. I can imagine the souls in there, the complicated actions inside, which also have a beauty. It’s not just beauty at this dimension of one centimeter; there’s also beauty at a smaller dimension. The inner structure, the processes, the fact that the colors and the flower are evolved in order to attract insects to pollinate it is interesting. It means the insects can see the color, which adds a question: is this aesthetic sense also exist in the lower forms? Why is it aesthetic? All kinds of interesting questions which science knowledge only adds to the excitement and mystery in the aura of a flower. It only adds to the excitement and mystery, but I don’t understand how it subtracts.

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Beyond AI: Creating the Conscience of the Machine

I have always been fascinated with the study of Artificial Intelligence.  I began my interest as many computer science majors by simulating intelligence through maze solving LISP automated mice.  These are brute force methods that appear to be intelligent by recursively exploring every possible solution.  This is not intelligence.  It is merely programmatic problem solving.

What is Artificial Intelligence?  How do we copy the creation that is the human mind and intellect, and impress that upon silicon and wires?  Is it even possible? 

Book

Beyond AI: Creating the Conscience of the Machine
by J. Storrs Hall

Artificial intelligence (AI) is now advancing at such a rapid clip that it has the potential to transform our world in ways both exciting and disturbing. Computers have already been designed that are capable of driving cars, playing soccer, and finding and organizing information on the Web in ways that no human could. With each new gain in processing power, will scientists soon be able to create supercomputers that can read a newspaper with understanding, or write a news story, or create novels, or even formulate laws? And if machine intelligence advances beyond human intelligence, will we need to start talking about a computer’s intentions?

This book contemplates several interesting topics related to artificial intelligence, including the consequences of actually creating a systems that is intelligent.  A lot of what is intelligence appears to be search and pattern matching.  It seems that we build complex associations that help us grapple with our environment and interact with others in an intelligent fashion. 

What is intelligence?  I believe that we will continue to see progress in developing artificial minds.  Predictive expert systems already provide a sense of “smarts” but they are not creating anything new.  Attempts to build systems that take inputs, learn and even postulate solutions (as in mathematical proofs) have been limited in their success.  It seems that these intelligent systems hit a “glass ceiling” beyond which they are unable to produce anything new.  

Tools, Programs and Links

SHRDLU is a program for understanding natural language, written by Terry Winograd at the M.I.T. Artificial Intelligence Laboratory in 1968-70. – http://hci.stanford.edu/~winograd/shrdlu/

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The Spiritual Brain

The study of neuroscience continues to expand.  As the name would suggest, the foundational science is the study of the nervous system which of course, includes the study of the brain.  As the study expands beyond the pure biological investigation, it branches to include the cognitive studies and modeling within computer science, including the study of artificial intelligence (AI).

I recently stumbled across this interesting book:

Book

The Spiritual Brain
A Neuroscientist’s Case for the Existence of the Soul
By Mario Beauregard, Denyse O’Leary

In this book, the authors discuss the various claims and studies that attempt to locate the “region” of the brain or “God gene” that is responsible for spiritual experiences (the emotion of faith, the sense of the presence of an outside intelligence, the connection to God).  In this they attempt to investigate and answer the question, has God created the mind or does the mind create God. 

Is the brain synonymous with “the mind”?   The brain appears to be the physical fabric in which the mind lives.  Instead of some special area of the brain that is predisposed to invent spiritual experiences, the mind has the ability to “wander” around within the brain, perceiving and communing with the eternal realities.

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Richard Feynman on Light

The amazing nature of light and the rest of the electromagnetic spectrum as described by one of Physics greatest teachers, Richard Feynman.

Richard Feynman’s Talk About Light

## Introduction
Richard Feynman was a renowned physicist who made significant contributions to the field of quantum mechanics. In this talk, he discusses the nature of light and how it can be used to understand the world around us.

## The Swimming Pool Analogy
Feynman begins by comparing the behavior of light to waves in a swimming pool. He notes that when many people are in the pool, the water becomes choppy and disordered. Similarly, when light enters a room, it interacts with objects and becomes disordered, creating a complex network of waves that can be difficult to understand.

## The Black Hole
Feynman then introduces the concept of a black hole, which is particularly sensitive to the direction in which light enters the room. He notes that when light enters the room at an angle, it is more difficult for the black hole to detect it. This is because the light is coming from the corner of our eye, which is not as sensitive to changes in direction as the center of our eye.

## The Corner of the Eye
Feynman then discusses the idea of using the corner of the eye to gain more information about the light entering the room. He notes that by swiveling a ball about, we can see the entire place and gain a better understanding of the light’s behavior.

## The White Ways
Feynman then compares the behavior of light to the waves in the swimming pool, noting that the white ways are easier to understand than the waves. He notes that the white ways are like the water height, going up and down in a combination of motions that produce an influence.

## The Light Bouncing Around the Room
Feynman then discusses the idea of light bouncing around the room, creating a complex network of waves that can be difficult to understand. He notes that most of the room does not have an eighth inch black hole, so it is not interested in the light bouncing around the room. However, the lights in the room do bounce off each other, creating a complex network of waves that can be difficult to understand.

## Conclusion
In conclusion, Feynman’s talk about light highlights the complexity and inconceivability of the natural world. He notes that by understanding the behavior of light, we can gain a better understanding of the world around us.