Lewis Loflin Electronics Background BiographyTweet
Lewis Loflin - title: applied technologist; Website: www.bristolwatch.com
Can you give us a little background about yourself? How did you get into electronics?
My first interest was geology and Earth science followed by history. My interest in electronics was an outgrowth of my interest in science. The reason I use the term "applied technologist" is because of my interest in applied science combined with electronics to create and build projects applicable to the real world.
Growing up very poor in an Appalachian coal town also shaped much of my thinking and the way I do things. In high school by the 10th grade I had already aced senior chemistry class (physics was dropped) and had run through every science class offered at the school. So I attended vocational school (TV repair believe it or not) much rather than studying basket weaving.
By the time I graduated high school I had won awards at the vocational school, mathematics and history awards at my high school, and the regional science fair. My science fair project consisted of a high-voltage section I built based on a black-and-white television and using a sealed glass tube with most of the air vacuumed out I could fire an ion beam onto a metal target within the tube. The beam could be moved around with magnets and differing gases produced differing effects.
An earlier graduate of my high school and later a mentor became a physicist and was on the team that developed NASA's thermal nuclear power generators for the Voyager space probes. Launched in the late 1970s these probes were the first to fly by Jupiter, Saturn, Uranus, and Neptune. They are still operating today and are set to exit the solar system in the coming years.
Another mentor was my elderly next door neighbor who was a ham operator. He built most of his equipment in the 1930s and it was still in use in the 1970s.
One of the things I do is take existing technology and find novel ways to use it sometimes in combination with older technology. The main reason for this is to give lower income people access to things they really couldn't afford. Why shouldn't a hobbyist for example not use an obsolete computer running GW Basic through say a printer port to control say a used stepper motor? They learn some hardware and programming at little cost.
Who would have thought to use a SIDAC or DIAC (used for solid state switching) as a relaxation oscillator? I have an article on the website for that.
Unable to afford college even though I graduated an honor student from a local high school I chose a path through the military. Graduating in 1978 at the top of my class my electronics training was oriented towards RF. At this time also I was exposed to some of the first microprocessors and single board computers such as the KIM-1 along with a bevy of strange classified military computers. A friend of mine at the time had one of the first Apple IIe computers that used the same 6502 microprocessor that was also the basis of the Commodore-64, VIC-20, and Atari.
Some computers of this time often consisted of nothing more than a circuit board and if one was lucky and could afford a mechanical teleprinter such as the ASR-33. Code was entered on the keypad or paper tape or simply switches. My KIM-1 used a hexadecimal keypad and some seven segment displays. Programs were saved to an audio tape recorder at the amazing speed of 300 baud.
Using only 1K of static RAM the KIM-1 community of that time created hundreds of programs and applications for this single board computer. By the way one had to supply their own power supply!
To me this was the most creative period until recently. With a single 1K of memory costing over $50 and hardware hideously expensive one had to be very creative with the technology available. We don't face that problem today as far as the cost of hardware, but the real problem seems to be lack of usable practical information.
My entry into electronics in the 1970s was at a transition point where the first true microprocessors were becoming available and at the trailing end of the age of vacuum tubes and mechanical teleprinters. What always fascinated me was what one could do in the creative sense with available technology. A mechanical teleprinter for instance has hundreds of moving parts, one motor, and one solenoid were used to print entire pages of text along with acting as a typewriter.
I also worked extensively with vacuum tube radios still being used by the military. Known as the R390 this radio was first engineered by Collins Radio in 1946 and is still in my view superior to any solid-state shortwave receiver. Note that vacuum tubes are immune to electromagnetic pulse, etc. that can destroy solid-state.
That is why one of the projects on my website is a vacuum tube radio that one can build. What has become interesting in recent years is many vacuum tubes and parts have become available once again via Ebay at low cost.
After the military I attended college but soon dropped out and got hired on the ground floor of the satellite TV industry. I was soon operating a warranty repair center for nearly every brand in the industry working for a distributor. Initially most satellite receivers were actually being built by very small companies before being later outsourced to Asia. Most of this equipment was direct takeoffs of military RF gear.
After the satellite TV industry collapsed in the early 1990s I went ahead and completed college obtaining degrees in university parallel and computer information systems. I had already taught myself to program in machine language for the 6502 microprocessor, and in college I had C, C++, Pascal, and assembly language for the Motorola 68000. My final class project was the building a plug-in card that allowed a common IBM PC (ISA buss) to operate as a digital storage oscilloscope. The software was Borland C++ for DOS.
I had completed college as an older student. By this time I had over 20 years of experience building electrical and electronics projects as a hobby along with two decades of circuit board and component level repair and trouble shooting.
After leaving college I went to work for company that repaired circuit boards and assemblies for industrial welders. This was my big introduction into industrial electronics. What made this job particularly interesting is I could make use of the many years of designing hobby projects combined with my electronics experience to build test assemblies for this company.
The trick I had to overcome in troubleshooting these industrial circuit boards is they came without the machine. So I had to design test fixtures to make the circuit boards function as if they were still in the machine for troubleshooting and repair.
One of the most interesting projects I was involved with was designing a test fixture to troubleshoot circuit boards from portable plasma cutters. The most dangerous aspect was the power supply and chopper boards operated at 240 to 460 volts AC.
When rectified and filtered the capacitors held the charge of over 700 VDC and can be lethal. These chopper boards used power MOSFETs and operating at over 32 kHz is what supplied the power to ionize a gas to cut through up to 2 inches of steel. This high-frequency enabled the designers to reduce the size and weight of the components.
If anything was wrong on the board the parts would literally explode like a shotgun. My trick was to test this in such a way to keep the board from literally blowing up if some minor part was still defective.
This was accomplished with a specialized test jig along with what I call a load lamp. That is featured on one of my YouTube videos and on my website is how to use a common light bulb in series with a power supply to keep from damaging circuit boards or other devices under test if something goes wrong.
I learned this trick years earlier in troubleshooting solid-state audio amplifiers which used direct-coupled transistors. (This was before the large scale integration of today.) A single bad transistor could short out and damage everything in the channel so I had to devise a way back then to keep this damage from happening. The light bulb simply absorbs the excess energy if there is a large surge or dead short protecting the solid-state components susceptible to surge damage.
Later on after leaving this company around 2000 I've been a part-time adjunct at a local community college teaching electricity and electronics. Sadly they dropped their entire electronics program and teach mainly house wiring today. While my main job today is contract security services I operate my website in order to give up-and-coming hobbyists and future engineers the inspiration to achieve on their own.
Tell us about your blog electronics projects for students.
My blog is my way of countering what I see as a failing and politically corrupted education system. Here in Southern Appalachia is famous for its culture of mass poverty and assumed failure. Our school systems, and I daresay a lot of lower income rural and inner-city school systems in general, operate on the basis of assumed failure.
In this area we graduate far too many functional illiterates and academically science and math have suffered horribly. (As they have across the nation.)
The attitude is pretty much one goes to a four-year college and leaves the region or one wires houses or works at Wall-Mart. Most electronics courses have been dumped by our local community colleges or at best watered down. This also comes from my almost 10 years as a part-time adjunct instructor and the problems I dealt with first hand.
I fought for years to try to get the science and math preparation for our technology students added to the vocational courses that I was teaching. The powers to be simply wouldn't hear of it. Yet we have industry in the region screaming they need better trained people yet our public school system and community colleges operate more like diploma mills.
Imagine trying to teach a class on basic electricity and semiconductors with students that can't move the decimal point, can't use a scientific calculator, and have no knowledge of even the most basic structure of an atom.
I managed to do it and at least got them interested in pursuing more on the subject. High school science classes around here consist mainly of biology survey classes. This kind of thinking in public education leaves most of our students at a great disadvantage. Many of these projects and videos were designed to help them.
To make matters even worse is many of the how-to books that I used as a kid to get my start into electronics science etc. no longer exist today. It was out of these books written in the late 1950s and early 1960s that showed one how to cut open a common transistor (assuming a metal can) could be used as a sensitive heat or light detector. Or to use a light emitting diode to detect light. Or how to take common household materials and make your own batteries.
In the public libraries and schools in this area those books simply no longer exist unless one wants a dated book on repairing CB radios. When I was a kid even here in Appalachia I could still find books and they still taught classes on how to use number systems such as binary, hexadecimal, and octal.
The typical student today has never heard of any of it despite the explosion in use of computer technology.
One course that I had developed for a local manufacturing plant was to train their maintenance personnel on basic electricity, semiconductors and troubleshooting. The poor students were literally sweating blood over the physics and math except for one of their oldest members. He caught right on to the semiconductor theory and mathematics because he had a chemistry class decades ago.
If schools would start just requiring courses in inorganic chemistry and basic physics this would give the students such a hands up with entering technical fields. Most of the schools in this region don't teach physics any longer. Education today is often memorization and trying to learn to pass a test. Critical thinking and problem solving, forget it.
Another problem in this region is the near total lack of high-tech jobs.
The end result is we have no computer clubs, no science clubs, no technology groups, and many technical and scientific courses in our local community colleges are either watered down or unavailable. One won't find a class in this region on say Linux.
What classes that are offered are oriented towards transfer engineering to other colleges and the assumption the student will leave the region or working in an office for eight dollars an hour staring at the Microsoft blue screen of death. This system to me is simply intolerable.
Today many school systems have dropped science fairs and honors classes and some colleges are talking about dropping even math requirements. Thus many students if they're going to get into technology in many regions of the country they will have to do it themselves and the Internet is one of the few positive developments in that regard.
In fact I've guided several students in Asia through their projects online when they were in college. So my goal is to both inspire and to try to hand them the tools to do it on their own which in reality I was forced to do. Virtually everything I know today is self-taught.
What tools software and hardware are your favorites?
I stick with the basics such as logic probes, digital volt meters, frequency counter, function generators, and an oscilloscope. I've pretty much assembled a testing lab of my own over the years. The cost of many of these items has dropped considerably in recent years. A good oscilloscope a few decades ago cost thousands of dollars while today one can be had for around $400.
What is on your bookshelf?
Don't laugh but World War Z and the Zombie Survival Guide by Max Brooks. Other titles include the History of Earth by William K. Hartmann and the Gnostic Gospels by Elaine Pagels. I do a fair amount of writing and research on theology and ancient history. I'm also still an avid fan of geology and aarth science. That makes up about half of my bookshelves which are considerable.
The other half consists of a broad range of electrical and technical subjects. The RCA Receiving Tube manual; the IBM PC from the inside out circa 1986. This is were I learned to get around in the hardware and IBM PC which enabled me to build my digital storage oscilloscope when I finally finished college.
Another title includes thyristor theory and applications where I actually sat down and built and tested the circuits in this book and along with my experience in industrial welder repair is the basis of the projects on my website such as the Arduino AC power control.
That's where I use something called a zero crossing detector with Arduino interrupts to control AC power. I even came up with a way to use three Arduino's using triacs can control AC power to the three-phase motor.
On the computer side you will find titles such as Damn Small Linux whose concepts I used to build a light weight Linux system for the Raspberry Pi. One problem I had that held me back for years is I simply didn't have the money to buy a lot of what I needed. The first IBM PC I ended up with was a circuit board I bought as salvage using an 8088 that I'd managed to repair. It had only 256K of RAM and I managed to build a power supply to operate it.
I was using DOS from a floppy drive and used GW basic to program and play with the hardware. So most of my time was spent using cast-off and obsolete computers. Thus I had find a Linux operating system that would operate on low power and obsolete hardware. So the book Damn Small Linux based on Debian and Knoppix got me going along with Puppy Linux. From there I moved up to full-scale Debian and learned how to set up FSTAB and program in C and C++ with the command line. I had already learned C and C++ in college and had enough knowledge to port it over to Linux.
So to largely summarize when I get interested in something I sit down and hack it and build it and I want to see it work in the real world. I have never taken a class in Linux. Recent additions to my bookshelf are mainly magazines such as the Linux Shell Handbook, Linux User and Developer, and Linux Format. They do a much better job at learning than say a college textbook, which often dwell on the abstract and theoretical and not the practical and hands-on.
Do you have any experimental stories you'd like to share?
Yes. When I was a kid I did make gunpowder and liked blowing things up. Actually I used it for model rocketry and yes they made some nice booms at times. There was one time I almost got myself injured and learned from there on to be more careful.
It's hard to say this or that experiment because one experiment laid the foundation for the next experiment. Right now I'm in the process of building a computer controlled miniature refrigerator to cool a couple of cans of sodas. This is all based on previous experiments. First I did experiments with Peltier modules which are solid-state refrigeration units.
The direction of heat flow from one side or the other can be altered by simply reversing the polarity. These units can also be stacked plus to minus and plus to minus to operate at a higher voltage. So I can use my H-bridge motor control project that's on the website to actually reverse the polarity when needed on a Peltier module and with the appropriate temperature sensor and an Arduino or other micro-controller can keep the sodas or whatever else I'm doing at a very precise temperature.
The H-bridge I designed could also be pulse-width modulated by a micro-controller to control the rate of cooling and heating with the Peltier module in addition to being able to reverse polarity and thus direction of heat flow.
So that experiment is the culmination of three previous experiments. And that is really the secret I use and it takes a lot of work to learn the little things in order to build bigger things. Simplistic it may be, but it seems to work.
It's also interesting to note that Peltier type modules when heat flows from one side to the other a DC voltage is generated. This was the basis of the power systems in the Voyager probes as the heat generated by a non-fissionable plutonium isotope was transferred through Peltier type modules to generate electricity to power the probes. The sun was simply too dim that far out to use solar panels.
As another example is that same H bridge motor control being used with a microprocessor can be connected to a step down transformer wired in reverse to generate 120 V to operate say a florescent light. That's also on my website.
The big project I'm working on now is learning more about the microchip PIC controllers. In many ways these resemble the 6502 which was also a type of RISC processor. And I'm doing this in assembly because using PIC basic or C hides most of the electronic aspects of the micro-controller. Using assembly language also makes for greater learning of electronics and more efficient coding.
Is there anything you'd like to say to young people to encourage them to pursue electronics?
First and foremost learn your basic science and math! That is vital particularly if one wants to get into machine control and robotics. The next thing I would advise is to take some basic computer languages such as C++ and assembly. Of course take some basic classes in electronics. In many cases these should have been taught in the public schools but don't count on it.
It's also vital to learn some hands on skills. Try to learn soldering or metalworking or any number of shop trades. There's nothing wrong with learning how to use a drill press or grinder. The way that I'm seeing things is we need the academics and the core learning, but we must learn hands on usable skills.
What's wrong with taking a course in say automotive wiring and using that to wire up a home built CNC machine? It's time to end this stigma against actually building things with one's hands.
I also see a big future with 3-D printers in making custom parts for projects. While pricey right now, prices will continue to come down.
Don't be ashamed to use existing examples and the work of others (with proper credit) to create your own inventions. I have no problem scouring the Internet or old textbooks for old but still useful information that can be produce new ideas.
There is also a lot of excitement over the Raspberry Pi computer. I'm looking myself into getting one and playing with it, but its uses are limited. It's useless for actual machine control but in combination with a Microchip PIC or Arduino can make a very powerful control system. And because it's operating system is essentially Debian Linux that can give a student some inspiration to learn real Linux. For myself I prefer Slackware and Debian.
Finally I would like to see more women and girls get involved in technology and electronics. It's hard to say electronics anymore because electronics has become such a part of so many things. So the range of subjects to learn can be very broad. But let's stick to the basics and from the basics one can always build greater and greater things.
- LM317 Constant Current Source for Lighting LEDs
- LM2575 Simple Switching Voltage Regulators
- Simple 2 Transistor LED Flasher Circuit
- Voltage Buck-Boost Transformer Connections Tutorial
- Arduino Buck Switching Voltage Regulator Demo
- Switching Regular Configuration Review
- Generating High Voltage with an Inductor
- Arduino Port Registers Revisited
- Digispark ATtiny85 with MCP23016 GPIO Expander
- Safely Build Program a H-Bridge
- Build H-Bridge Motor Control Without Fireworks
- MOSFET H-Bridge for Arduino 2
- Arduino Projects Revisited Revised
- Some Sample YouTube Videos
- Arduino Solar Battery Charge Controller
- Zener Diode Tutorial
- Simple Power Distribution for Prototype Board
- Program Arduino Ports for Speed and Control
- Safely Program H-Bridge Motor Controller
- Build H-Bridge Motor Control without Fireworks
- MOSFET H-Bridge for Arduino 2