I'm Retiring From My Full Time Engineering Faculty Position at Holyoke Community College

“Often when you think you’re at the end of something, you’re at the beginning of something
else.” – Fred Rogers

After an enriching and fulfilling career spanning five decades, I am announcing my retirement from my full-time engineering faculty position at Holyoke Community College (HCC) effective August 30, 2024. This decision comes with mixed emotions, as I reflect on the journey that has shaped not only my professional life but also my personal growth.

Teaching has been more than just a job; it has been a vocation that allowed me to inspire and nurture countless students, guiding them through the complexities of engineering principles and practices. My time in academia has been marked by moments of profound satisfaction, seeing students evolve into competent and confident engineers and technologists, ready to make their mark in the world. Each graduation ceremony, each successful project, and each breakthrough in understanding (and of course each belly-flop failure) has reinforced my belief in the power of education.

The field of engineering itself has undergone tremendous transformation during my tenure. From the early days of teaching with chalk and blackboards to leveraging cutting-edge technology and online platforms, I have witnessed and embraced these changes, ensuring that my students received the most current and relevant knowledge. The shift towards digital learning, in particular, has been a remarkable journey, one that demanded continuous adaptation and learning on my part.

Retirement from HCC marks the beginning of a new chapter, where I am eager to channel my energy and expertise into some exciting consultancy projects, writing, mentoring, and of course some part-time teaching. The flexibility will allow me to spend more time with my family and yeah (!) - get in a little more fishing. 

Will this be a “sabbatical”  or a permanent change? Having experienced "retirement" in the past and not having it “stick”, I've learned to appreciate the unpredictability of life. This journey has taught me to embrace uncertainty and always stay open to whatever opportunities and possibilities the future may bring.

My academic career has been a tapestry woven with dedication, passion, and countless rewarding experiences. I carry with me a wealth of memories and the profound satisfaction of having contributed to the field of engineering and to the lives of so many young minds. 

How Is Battery Percentage Measured On My Device?

I get this question often - how is battery percentage measured and calculated by devices like our
phones, leaf blowers, electric cars, etc?  

It turns out most modern Battery Management Systems (BMS) use a combination of four variables to estimate the remaining charge in a battery.

 

1.    Voltage Measurement: Used to provide quick and direct State Of Charge (SOC) estimates  but can be inaccurate due to load variations. There are two measurements typically  considered:

• Open-Circuit Voltage (OCV): This measures the voltage when the battery is not under load. Each battery type has a characteristic voltage curve that relates voltage to SOC.
• Under-Load Voltage (ULV): This measures the voltage while the battery is under load. Compensation is required to account for the voltage drop due to internal resistance. 

2.    Coulomb/Charge Counting:  Precise over short periods but can drift over time due to measurement inaccuracies.

• Coulomb/Charge Counting involves tracking the current flowing in and out of the battery. By integrating the current over time, you can estimate the total charge added or removed. This method needs a known initial state of charge to be accurate.      

3.    Impedance Tracking: Provides additional data to refine SOC estimates but requires complex algorithms and computations.

• Impedance Tracking uses the battery's internal impedance (reciprocal resistance) which changes with the state of charge. By measuring the impedance, the state of charge can be estimated.

4.    Temperature Compensation: Battery performance and voltage readings can be significantly affected by temperature. 

• Temperature sensors are used to adjust the SOC calculations.

Battery Capacity

Battery capacity C for a new battery is a given and specified by the battery manufacturer in ampere-hours (Ah) or milliampere-hours (mAh) units, depending on the size of the battery. As an example, the iPhone 15 Pro is equipped with a single battery rated at 3274mAh.  If you are wondering about your Tesla or Prius - batteries are wired in parallel – for example a 2020 Long Range Tesla Model 3 battery pack has 46 cells in parallel with each cell rated at 5 Ah. So that Tesla battery pack has about 46x5 Ah = 230 Ah capacity. Over time, battery capacity will decrease.

 

Some Variables

Let’s look at a couple of simple calculations used by our devices to calculate battery charge/percentage. Before we look at the formulas, let’s identify some variables used in the calculations.

 

Initial Calibration:

• Battery starts fully charged (100% SOC).
• OCV is measured to establish a reference point.

Discharge Phase:

• Voltage is continuously monitored.
• Coulomb counting tracks the charge removed.
• Impedance is checked periodically to refine the SOC estimate.
• Temperature compensation adjusts the readings. 

State of Charge Calculation:

• Combining the voltage, coulomb count, and impedance data, the BMS computes the SOC.
• This value is then translated into a percentage to display the remaining battery life. 

Finally - A Couple Formulas

There are two formulas commonly used - the first uses current (Coulomb Counting) and the second voltage (Voltage-Based SOC Estimation)

 

Formula for Coulomb Counting Estimation:

Formula for Voltage-Based SOC Estimation:

Battery percentage calculations rely on sensor measurements that account for the various factors affecting battery performance. Using real time sensor data, BMS algorithms continue to advance, providing estimates of remaining battery charge.

Chaos Engineering: Embracing Disorder In Resilient Systems

In my last post I wrote about resilience engineering – interesting stuff but can it be tested? Of course!

Growing up in the 1960s one of my favorite shows was Get Smart, a classic comedy TV series parodying the spy genre, following bumbling secret agent Maxwell Smart and his adventures against the villainous organization KAOS, The International Organization of Evil.

Like the TV show, in the world of engineering, unpredictability and chaos are often viewed as adversaries to be conquered. However, a paradigm shift has occurred in recent years, with some engineers embracing chaos as a means to build more resilient systems. This approach, aptly named "Chaos Engineering," is a discipline that advocates deliberately injecting failure into systems to test their robustness and identify weaknesses before they cause real-world disasters.

 

At its core, Chaos Engineering is about embracing the inherent unpredictability of complex systems and using it to our advantage. Instead of waiting for failures to occur in production, engineers proactively introduce controlled chaos to observe how systems respond under adverse conditions. By doing so, they gain valuable insights into system behavior and dependencies, enabling them to build more resilient architectures.

[image credit: https://www.bmc.com/blogs/chaos-engineering/]

The principles of Chaos Engineering are grounded in scientific experimentation. Engineers start by defining a hypothesis about how their system should behave under stress. They then design and execute experiments that simulate real-world failures, such as server crashes, network latency spikes, or database outages. These experiments are carefully controlled to minimize the impact on users while still providing meaningful insights into system behavior.

 

One of the key benefits of Chaos Engineering is its ability to uncover hidden weaknesses in distributed systems. In today's world of microservices and cloud computing, systems are becoming increasingly complex, with numerous interdependencies and failure points. Traditional testing methods often fail to uncover these issues until they manifest in production. Chaos Engineering helps mitigate this risk by actively probing for weaknesses in a controlled environment.

 

Netflix is perhaps the most famous proponent of Chaos Engineering, with its "Chaos Monkey" tool being widely used to inject failures into production systems. By regularly causing disruptions in their infrastructure, Netflix ensures that engineers are constantly aware of potential weaknesses and can design systems to withstand them. This approach has helped Netflix achieve unprecedented levels of uptime and scalability, even in the face of unexpected events like server outages or network failures.

 

However, Chaos Engineering is not without its challenges. Introducing chaos into a system requires careful planning and coordination to ensure that experiments do not cause widespread outages or data loss. Moreover, interpreting the results of chaos experiments can be complex, as system behavior is often non-linear and influenced by numerous factors.

 

Despite the challenges, the benefits of Chaos Engineering are undeniable. By proactively testing for weaknesses and building resilience into their systems, engineers can improve uptime, reduce downtime, and ultimately deliver a better experience for users.

Distributed Inference And Tesla With Some SETI Nostalgia

In this post, I’m setting aside any political stuff and focusing solely on tech.

 

In recent months, the electric vehicle (EV) market has seen a decline, marked by falling sales and an increase in unsold inventory. Tesla, in particular, has received a significant share of negative attention. During Tesla's first-quarter earnings call last week, Elon Musk diverged from the norm by highlighting Tesla's broader identity beyond its role in the automotive industry. He emphasized the company's engagement in artificial intelligence and robotics, suggesting that pigeonholing Tesla solely within the EV sector overlooks its broader potential.

 

Musk's suggestion to actively utilize Tesla's computational power hints at a larger strategic vision. He envisions a future where idle Tesla vehicles contribute to a distributed network for AI model processing, termed distributed inference. This concept could leverage the collective computational strength of millions of Tesla cars worldwide, extending the company's impact beyond transportation.

 

Very interesting – I drive maybe 1-2 hours per day, the rest of the time my car is not being used. What if all that computing horsepower could be used while I’m not using it? Musk’s concept brings up memories of the sunsetted SETI@home computer application. SETI was a distributed computing project that allowed volunteers to contribute their idle computer processing power to analyze radio signals from space in the search for extraterrestrial intelligence (SETI). SETI@home used data collected by the Arecibo Observatory in Puerto Rico and the Green Bank Telescope in West Virginia to search for patterns or anomalies that could indicate the presence of intelligent alien civilizations.

 

Participants in SETI@home downloaded a screensaver or software client onto their computers, which would then process small segments of radio telescope data during periods of inactivity. The processed data would be sent back to the project's servers for analysis. By harnessing the collective power of millions of volunteer computers around the world, SETI@home was able to perform computations on an unprecedented scale. The project was launched in 1999 by the University of California, Berkeley, and it quickly became one of the largest distributed computing projects in history. Although the original SETI@home project ended in 2020, its legacy lives on as an example of the power of distributed computing and the widespread public interest in the search for extraterrestrial life.

 

Musk's vision underscores Tesla's potential to revolutionize not only the automotive sector but also broader domains such as artificial intelligence and robotics. It signifies a strategic shift towards leveraging Tesla's resources and expertise in a SETI-like way to drive innovation and create value in new and unexpected ways.

Lost Text and Lost Friend: Terry Pardoe and Data Communications, Networking Methods and Protocols

 

In 2003-2004, I collaborated with Terry Pardoe, co-authoring a Network Security book published in 2004. Inspired by its success, in 2005 we began work on another book titled Data Communications, Networking Methods and Protocols, which unfortunately never made it to publication. Fast forward to September 2014, where I had the honor of delivering the opening keynote for the fall semester at New Hampshire Community Technical College (NHCTC) in Nashua. Terry played a pivotal role in making this happen, and during the event, we had the chance to capture the photo here together, proudly holding our first co-authored text.

I first crossed paths with Terry back in 1999 when he joined NHCTC-Nashua as a part-time lecturer and became a subject matter expert in the (sunsetted in 2016) Verizon NextStep program. Despite a rocky start, our relationship quickly blossomed into a close friendship. Terry possessed a remarkable sense of humor, though I can't recall ever seeing him laugh. He sure knew how to make me laugh though. He resided in Nashua, New Hampshire, alongside his wife and family. A few years ago I learned Terry passed away on May 2, 2016 at the age of 76. Years later and I’m just finding out – it happens to us all - people we work with and are friends with – we lose touch when things change. Before we get into the content – here’s a little bit about Terry.

 

Terry was born in the United Kingdom and educated at the Birmingham College of Advanced Technology (Now Aston University). After coming to the states, Terry D. Pardoe was executive vice president of International Management Services Inc. a USA based computer application and training organization for 23 years (until Aug 1999). On his death, he had more than 40 years experience in the design and application of networks, communications and information systems. He was an internationally recognized expert on all aspects of telecommunications and networking including wide and local area networks, TCP/IP based networks, the Internet, intranets, client server computing, data and network security and many other applied areas. He lectured and consulted on a worldwide basis for a wide range of clients including: Digital Equipment Corp., AT&T, Sprint United, Verizon, Citibank, IBM, Honeywell, NT&T (H.K.), SCI (Brazil), etc. Terry worked with all the major agencies of the US Government including NASA, NSA, DISA, US Navy, US Army, IRS and many others.

 

Terry was the author or co-author of over 200 technical texts on computer applications, management techniques and data communications including text to support the first Java seminar available on a worldwide basis. He authored many www pages which include complex graphics, Java applets and JavaScript.

 

Today I found an old CD-ROM with all text, images, etc intact of the Data Communications, Networking Methods and Protocols book. Over the summer I’ll be posting content from that unpublished book here in honor and respect of Terry. It is interesting – 20 years later - a combination of some obsolete but other still relevant technologies.

 

An amazing man and an amazing career, building the foundation for the Internet we have today. Thanks Terry!!

555 Timer: Astable Mode

The 555 timer IC is a popular integrated circuit (IC)  used in various electronic projects and can be configured to perform a wide range of tasks. It was first introduced by Signetics (now part of ON Semiconductor) in 1972 and has since become one of the most widely used ICs in the electronics industry due to its simplicity and versatility. The 555 timer IC is available in different variants, including the NE555, LM555, and others, with minor variations between them.

The 555 timer operates over a wide range of power supply voltages, typically from 4.5 volts to 15 volts and is typically used in one of three operating modes:

• Astable Mode Operation: In this mode, the 555 timer acts as an oscillator, generating a square wave output signal. This mode is commonly used in applications like LED flashers, pulse generators, and tone generators.

• Monostable Mode Operation: In this mode, the 555 timer functions as a "one-shot" pulse generator. It produces a single pulse of a specified duration in response to a trigger input. Applications include timers and delay circuits.

• Bistable Mode Operation: This mode is used to create a flip-flop circuit, which has two stable states and is often used in simple digital logic applications.

Depending on how a 555 timer is to be used, the appropriate configuration and values for the timing components (R1, R2, and C) must be selected to achieve the desired output characteristics or time delays. Here's some details:

• Timing Component Operation: The 555 timer's timing is determined by two resistors (R1 and R2) and a capacitor (C). By choosing appropriate values for these components, you can set the desired time intervals for the timer's operation.

• Internal Comparator Operation: The 555 timer includes an internal comparator that compares the voltage across the timing capacitor with two-thirds of the supply voltage and controls the output accordingly.

• Output Stage Operation: The 555 timer has an output pin (usually labeled as "OUT") that produces either a high or low signal based on the timing mode and the voltage across the timing components.

• Trigger and Reset Input Operation: The IC has a "TRIG" (trigger) input and a "RESET" input. The trigger input is used to initiate certain modes of operation, while the reset input is used to reset the timer and interrupt its operation.

• Threshold Input Operation: The "THRS" (threshold) input is used in some applications to override the internal voltage divider.

Here's a short PSpice video I made demonstrating how the 555 Timer can be used in Astable Mode.

The 555 timer is still one of the most popular components used in timing-related applications. 

MATLAB Tip Calculator on Your Phone

In this video I show how to take your MATLAB code and run it on your iPhone. 

Here's a list of instructions you can use while watching the video.

In MATLAB on Your Computer

• Create a MATLAB script or function.

• Document your code by adding explanatory comments at the beginning of the file and within each section.

• Publish the code. On the Publish tab, click Publish.
• By default, MATLAB creates a subfolder named html, which contains an HTML file and files for each graphic that your code creates. The HTML file includes the code, formatted comments, and output. Alternatively, you can publish to other formats, such as PDF files or Microsoft PowerPoint® presentations. For more information on publishing to other formats, see Specify Output File.
• In MATLAB Online™, to allow MATLAB to open output windows automatically when publishing, enable pop-up windows in your Web browser.

• After publishing the code, you must share the folder containing the published files. For more information, see Share Folders in MATLAB.

• To share a folder from MATLAB®, MATLAB Drive Connector must be running and the folder you choose to share must be in your MATLAB Drive. If you are working in MATLAB Online, you do not need MATLAB Drive Connector to share folders since sharing is always enabled.
• See: https://www.mathworks.com/products/matlab-drive.html

• To save to the MATLAB Drive, in MATLAB select Publish -> Save -> Save As -> navigate to MATLAB-Drive and save tipcalculator.m there.

On Your Phone

• Install the MATLAB app on your phone, login to your account and access the script saved in to cloud. You must have internet access to access.

• Impress your family and friends with your tip knowledge, skills and abilities!

And if you want to also impress them a little more, here's how to mirror your iPhone screen on a Mac.

1. Connect your iPhone to your Mac with a USB cable.
2. Open the QuickTime Player on your Mac.
3. Click “File”, and choose “New Movie Recording”.
4. Click the Options pop-up menu, then Choose Your Connected iPhone. ...
5. The iPhone screen will now instantly display on the Mac.

MATLAB Tip Calculator Fix-Up

This summer I'm building a series of MathWorks MATLAB (short for Matrix Laboratory) videos for an introductory online course I'm putting together at Holyoke Community College.

 

In this video I fix-up a previously saved tip calculator script in MATLAB. In the next video I'll show you how to transfer the script to your cell phone so you can use it when you eat out!

The course will start from ground zero assuming the student has no experience with MATLAB and work up to some interesting and powerful analysis techniques. Over the summer I’ll be posting additional MATLAB videos as teasers for the complete course.

 

Want to learn more? Come take a course with me at Holyoke Community College. If you are anywhere in the world and interested in taking an online course, drop an email to gsnyder@hcc.edu Our courses will transfer to most university engineering programs in the United States. 

Write, Save and Run A Tip Calculator Using MATLAB Scripting

This summer I'm building a series of MathWorks MATLAB (short for Matrix Laboratory) videos for an introductory online course I'm putting together at Holyoke Community College.

In this video I demonstrate how to write, save and run a tip calculator script in MATLAB. In the next video I'll show you how to transfer the script to your cell phone so you can use it when you eat out!

The course will start from ground zero assuming the student has no experience with MATLAB and work up to some interesting and powerful analysis techniques. Over the summer I’ll be posting additional MATLAB videos as teasers for the complete course.

 

Want to learn more? Come take a course with me at Holyoke Community College. If you are anywhere in the world and interested in taking an online course, drop an email to gsnyder@hcc.edu Our courses will transfer to most university engineering programs in the United States. 

MATLAB Basic Functions Video - Restaurant Tip Calculator

This summer I'm creating a series of MathWorks MATLAB (short for Matrix Laboratory) videos for an introductory online course I'm putting together at Holyoke Community College. Here's a new 4 min 52 sec how-to video using a simple restaurant tip calculation as an example.  Full course videos and content will get into the MATLAB app with lots of hands-on practical and fun examples.

The course will start from ground zero assuming the student has no experience with MATLAB and work up to some interesting and powerful analysis techniques. Over the summer I’ll be posting additional MATLAB videos as teasers for the complete course.

 

Want to learn more? Come take a course with me at Holyoke Community College. If you are anywhere in the world and interested in taking an online course rop an email to gsnyder@hcc.edu Our courses will transfer to most university engineering programs in the United States. 

PSpice Lab Series Video 5 - Batteries In Parallel

Maybe you've got an RV or a boat with four or more house batteries used to power an air conditioner, oven, electric grill, etc. Maybe you've got a cabin off the grid and are harvesting solar energy to charge a battery bank. Ever wonder what those batteries are doing and how they are hooked up?

In this video I use PSpice to demonstrate how multiple batteries are connected in parallel in a power inverter, solar hybrid inverter or UPS (Uninterruptible Power Supply) to increase capacity and run your ac, oven, etc longer on a full charge.

For more PSpice laboratory simulations, visit my YouTube PSpice Playlist.

Want to learn more? I’ll be teaching a Systems 1 course online in the fall and a Systems 2 course in the spring at Holyoke Community College. If you are anywhere in the world and interested in taking an online course with me drop an email to gsnyder@hcc.edu Both courses will transfer to most university electrical engineering programs in the United States. 

Hope to see you there!!

Internet Access In Support Of The Cuban People

I was in Cuba four years ago. The government had tight control of just about everyone and everything including Internet access back then so I’m not at all surprised they’ve been able to shut communications down amid the protests. I’ve been reading a lot about alternative access for Cubans lately. Satellite has been getting a lot of questions but the network and mobile devices are still a ways out. 

Today, balloons probably offer the best solution. Google actually has them ready to go with project Loon. Loon has been proven in collaboration with Telecom Kenya and used in Puerto Rico in partnership with AT&T and T-Mobile after Hurricane Maria. Each Loon balloon is made of polyethylene and has solar panels for electricity. They float between 60,000 and 75,000 feet which is above commercial airline height and provides 4G cell service to an area about the size of a tennis court. The problem – Loon requires network integration with a telco to provide service along with some equipment on the ground. Loon also requires permission from local regulators — something that the Cuban government surely would not grant.

Marcell Felipe, founder of the Inspire America Foundation, an organization dedicated to promoting democracy in Cuba and the Americas has been discussing a slightly different balloon idea without a lot of detail. Felipe claims he has been talking for a couple years with a contractor (not named, but could it be….??) that could deploy balloons that provide mobile phone connectivity without the participation of a ground provider. In comments to The Associated Press, Felipe has claimed it wouldn’t be feasible for the Cuban government to block these balloon-delivered signals “in any significant manner.″

Pic: Telecommunications Building, Revolution Square Havana. G Snyder 2017

Pspice Lab Series Video 3: Moving The Reference Ground Around

Zero volts reference, also known as ground is always a confusing topic. What if ground is placed at different locations in a circuit? In this 11 minute and 42 second video I use PSpice to show what happens when you move a ground around in a series circuit.

Want to learn more? I’ll be teaching a Systems 1 course online in the fall and a Systems 2 course in the spring at Holyoke Community College. If you are anywhere in the world and interested in taking an online course with me drop an email to gsnyder@hcc.edu Both courses will transfer to most university electrical engineering programs in the United States. Hope to see you there!!

Pspice Lab Series Video 2: Simple Series Resistive Circuits

 Here's a second PSPice video covering analysis of a simple series circuit with two dc voltage sources and four resistors.

Want to learn more? I’ll be teaching a Systems 1 course online in the fall and a Systems 2 course in the spring at Holyoke Community College. If you are anywhere in the world and interested in taking an online course with me drop an email to gsnyder@hcc.edu Both courses will transfer to most university electrical engineering programs in the United States. Hope to see you there!!

PSpice Lab Series Video 1

Over the summer I’ll be working on a series of OrCAD PSpice videos. PSpice is one of the most common analog and mixed signal circuit simulator and verification tools used by electrical engineers to rapidly move through the design cycle, from circuit exploration to design development and verification. It is also a lot of fun to play around with!

I’m developing a series of 25-30 online experiments that we’ll be using in my EGR223 - System Analysis (Circuit Analysis 1) and EGR 224 - System Analysis (Circuit Analysis 2) courses at Holyoke Community College. Here’s the first video in the series.

OrCAD has an excellent academic program that provides students and educators with a complete suite of design and analysis tools to learn, teach, and create electronic hardware. If you are a student or educator you can download the software here for free and follow along with my labs. If you are not a student or educator (or perhaps considering) you can download and install a trial version of the software here.

I’ll be teaching the Systems 1 course online in the fall and the Systems 2 course at Holyoke Community College in the spring so if you are anywhere in the world and interested in taking a course with me drop an email to gsnyder@hcc.edu Both courses will transfer to most university electrical engineering programs in the United States. Hope to see you there!!