Sloppy Reflow Soldering

I'm giving a quick talk at $WORK about the genmon raspberry pi project I'm working on, and the scope of that project. Ideally, this will go from problem statement, circuit design, schematic capture, board layout, PCB fabrication and construction. In 20 minutes!

Part of that is the magic of reflow soldering with solder paste for the SMT components on the board.

To illustrate this, I just squirted way too much paste on six 0603 resistor locations on the PCB, dropped some resistors on it.. and then cooked it with the hot air tool. Components go surfing on way too much solder.

The result is a hot mess, as expected, but demonstrates that the paste is really tiny solder balls suspended in the magic flux. And the awesome power of surface tension and how it pulls parts around at that small scale.

And this nicely illustrates why we have solder paste stencils. Or maybe thinner dispenser needles. Or something.. else.. not this.

Here it is! Enjoy! (Yeah, I know the clock on the microscope camera is wrong...) thumb Sloppy Reflow

COVID-19 Resources

COVID-19 Banner

There's been a whole lot of information, good and bad circulating on the COVID-19 virus and what to do about it. I've found some useful resources that you might also find helpful as well. I have tried to include references where possible regarding the sources of information and if you can trust them. I'm confident these data are more useful and accurate than random re-posting on Facebook or other social media.

Wash your hands!

Wash your hands with soap, and for at least 20 seconds. This hand washing with soap isn't to just remove the virus from your hands, the soap molocules actually destroy the structure of the virus itself, deactivating it. And don't touch your face.

Here's how the World Health Organization (WHO) tells us how to watch our hands, like a surgeon does.

Here's a good video, How soap kills the coronavirus that's less than 4 minutes long that explains why this works this nicely. Make sure you wash all parts of your hands, all your fingers (don't forget the thumbs!), the back of your hands and under fingernails.

Wash your groceries!

I found this YouTube video on Safe Grocery Shopping in COVID-19 Pandemic that looks like it's good information.

CDC Resources

When in doubt, go to the horse's mouth: The CDC. Put down the facebook and back away. There's too much misinformation floating around that's not helping.

Tracking the Extent of the Pandemic Progression

JHU Dashboard

The Johns Hopkins University has created a geographical visualization of the global pandemic spread that you've probably seen in the background of some news reports. You can browse this directly, and see global as well as country level numbers (and for some countries, further break downs by state/province/region).

The group at JHU publishing this data are more modeling and data science rather than medical people. Given that Johns Hopkins has a recognizable and valuable brand and reputation, I would tend to believe this presention of the data is accurate. As the source of the data is reported by all these different countries, there's an element of unknown quality for any given country reporting accurately or not.

United States Coronavirus (COVID-19) Tracker

This is a dashboard produced by some guy, plotting reported data on a county-by-county basis in the US. This provides are more granular level of detail than the JHU Dashboard does, which only displays aggregated data by state.

Coronavirus Disease (COVID-19) – Statistics and Research

This data presented as described below, with raw data for worldwide COVID-19 spread from the EU CDC

The purpose of this article on COVID-19 is to aggregate existing research, bring together the relevant data and allow readers to make sense of the published data and early research on the coronavirus outbreak.

Most of our work focuses on established problems, for which we can refer to well-established research and data. COVID-19 is different. All data and research on the virus is preliminary; researchers are rapidly learning more about a new and evolving problem. It is certain that the research we present here will be revised in the future. But based on our mission we feel it is our role to present clearly what the current research and data tells us about this emerging problem and especially to provide an understanding of what can and cannot be said based on this available knowledge.

State directives and Information

Maryland Department of Health Coronavirus Disease 2019 Outbreak page.

Includes county-level maps of confirmed cases.

Pennsylvania Coronavirus information

From the State Department of Health. This is where they announce closings and other social distancing measures. As of March 19th, 2020, all "Non-Life-Sustaining Businesses" were ordered to close by the Governer

Pennsylvania Joins New York, New Jersey and Connecticut's Regional Coalition to Combat COVID-19

Information regarding the coordination of multiple states on COVID-19 response.

New York State Information on Novel Coronavirus

Information on business closings, work-from-home directives and similar. Directory of County Health Officials of New York State here.

California COVID-19 Site

State of California COVID-19 information.

What's exponential growth and how fast is this spreading, and what's to be done?

Exponential growth is the problem. This pandemic in its rapid growth stage doubles the number of infected people every few (2-3) days. Early on, the numbers are small, once it takes off, the growth is very rapid. This is why early action, even just measured in a few days can have huge impact on the progression.

This is the whole "flatten the curve thing" - to slow the rapid growth and spread it out over a longer period of time to avoid filling up hospital beds, especially the limited ICU beds and not being able to handle any more critical condition patients. This is what's happening in Italy, and what people in the US (especially in NYC) are terrified of. If you can't treat seriously ill patients, the mortality rate goes up and you have "avoidable" deaths due to inadequate treatment because there are no ventalators to help people breathe.

Here's some info I've found that appears to be credible, but I've included what biographical information that I can find so you can make your own judgement on the trustworthyness of these non-governmental sources.

Some widely read postings from Tomas Pueyo

Tomas Pueyo is a Stanford guy with a MSc in Engineering and Stanford MBA that writes about health. According to LinkedIn he's not a medical guy; his thing is analytics. And this Coronavirus thing is all about the numbers to try to measure and track the growth and spread.

Here's a blog posting Coronavirus: Why You Must Act Now that looks at how and why the spreading of the disease progresses so rapidly. It also, crucially, makes the point that the number of cases that you see reported today is what was really happening some days ago - infections that happen well before symptoms occur and testing confirms this.

The same author has also just written Coronavirus: The Hammer and the Dance which is a follow-up to the first link. It talks about what measures can be taken now to limit the spread and one opinion on how things can play out. He says:

When you’re done reading the article, this is what you’ll take away:

Our healthcare system is already collapsing. Countries have two options: either they fight it hard now, or they will suffer a massive epidemic. If they choose the epidemic, hundreds of thousands will die. In some countries, millions. And that might not even eliminate further waves of infections. If we fight hard now, we will curb the deaths. We will relieve our healthcare system. We will prepare better. We will learn. The world has never learned as fast about anything, ever. And we need it, because we know so little about this virus. All of this will achieve something critical: Buy Us Time.

If we choose to fight hard, the fight will be sudden, then gradual. We will be locked in for weeks, not months. Then, we will get more and more freedoms back. It might not be back to normal immediately. But it will be close, and eventually back to normal. And we can do all that while considering the rest of the economy too.

I don't know what the credentials of the author of the previous 2 articles are; he's making projections based on data that's been published and the methods seem sound and not obviously crazy.

Stanford Researcher's info

Here's another bit information How to fight the coronavirus SARS-CoV-2 and its disease, COVID-19 by Michael Lin, PhD-MD at Stanford Medical. This is a presentation he put together for the Stanford community and published externally for others.

He seems like a well informed person based on his biography published by Stanford.
He's also Principal Investigator at (a lab that he runs)[http://med.stanford.edu/linlab.html] that does related research. So I would tend to lend some credence to his opinion.

Now the presention that I linked to gets a bit technical in the middle, but is surrounded by practical information, including his recommendations on what you as an individual person should be doing.

He also has good hints on how to keep your hands sanitary and clean.

Some YouTube videos from informed sources

Here's some YouTube videos from quality sources you can review if you like. (Note that on YouTube, you can easily speed-up the playback speed to 125%, 150%, 175% or 200% of the normal speed.)

UCSF Experts on the Epidemiology, Science, & Clinical Manifestations of COVID-19, and UCSF Response

In this UCSF Medical Grand Rounds presentation (March 19, 2020), nine UCSF experts describe the epidemiology, virology, clinical manifestations, pathophysiology, and treatments for COVID-19. The session is hosted by UCSF Department of Medicine chair Bob Wachter.

Program

Bob Wachter: Introduction

0:03:00 - Diane Havlir: Epidemiology

0:15:00 - Jen Babik: Clinical Presentation

0:26:00 - Michael Matthay: The Lung Disease of COVID-19 (ARDS), Clinical Aspects and Pathophysiology

0:36:00 - Annie Luetkemeyer: Treatments, Now and On the Horizon

0:55:00 - Q&A

1:02:00 - Panel Discussion on the UCSF Response, with 5 more UCSF experts: Matt Aldrich (Critical Care) Sarah Doernberg (ID and Infection Prevention), Chaz Langelier (Virology and Testing), Brad Monash Hospital Medicine), and Debbie Yokoe (ID and Epidemiology)

1:39:00 - Bob Wachter: Closing

COVID-19: Johns Hopkins University Experts Discuss Pandemic Response, Social Distancing, and More

PiDP-11 Introduction

Necrocomputing and nostalgia

Behold and enjoy a photo of my PiDP-11, a PDP-11/73 working scale model replica based on a Raspberry Pi running a PDP-11 emulator. Blinkenlights FTW!

You know you want one..

This Photo is my PiDP-11.