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Quorten Blog 1

First blog for all Quorten's blog-like writings

Path of action for repairing a CRT with jittery vertical deflection

quorten

2020-02-26

Categories: raspberry-pi  
Tags: raspberry-pi  

So, I have a CRT monitor that has jittery vertical deflection. How would I go about diagnosing and repairing this? Is the flyback transformer at fault? Nope, the flyback transformer strictly controls horizontal deflection and high voltage generation. It’s also good to know the flyback transformer functions as a failsafe to prevent screen burn if horizontal deflection fails.

20200226/https://en.wikipedia.org/wiki/Flyback_transformer
20200226/DuckDuckGo crt vertical deflection jittery
20200226/https://www.repairfaq.org/sam/deflfaq.htm

Oh, so now this good CRT repair FAQ that I found indicates that indeed, the flyback transformer and other complexities are primarily elements of horizontal deflection. But, if vertical deflection is at issue, that is not nearly as much of a problem to diagnose because the frequencies are lower, and therefore the circuitry is simpler. Often times in newer CRT sets, almost all vertical deflection circuitry is handled by a single integrated circuit. That’s great to know! Because… as is often the case with such integrated circuits, all of the required circuitry except for capacitors are included in the integrated circuit. And with chips, it’s typically either all or nothing.

Read on →

A coworker's advisor page

quorten

2020-02-25

Categories: random  
Tags: random  

Somewhere in this advisor’s webpage of one of a coworker of mine is a list of meaningless phrases to put inside letters of recommendation. I wasn’t given a specific location, but I’m told it’s in there somewhere.

20200225/https://www.math.ias.edu/avi/home

Explaining fundamentals of the stock market in basic terms

quorten

2020-02-25

Categories: personal-finance  
Tags: personal-finance  

The stock market. Stocks, shares, buying, selling, price goes up, price goes down. How does it all work? How can it work at a very basic foundational level? Some careful reading of the mere introductions on Wikipedia, some careful thought, and most importantly, some concrete examples are very helpful.

20200224/https://en.wikipedia.org/wiki/Stock_market
20200224/https://en.wikipedia.org/wiki/Stock

So first, the basic definitions, simplified for the purposes of our simple primary example to give first.

  • Equity and capital synonyms for money/currency. Therefore, the equity or capital of a company is simply how much money a company has. (More on this later.)

  • A share is a fractional ownership of a company out of the total number of shares.

So, let’s give a simple example. Suppose a company has $100 in equity and 10 total shares. Therefore, the price of one share is 1/10 of the total equity, or $100 / 10 = $10. This is how much money a shareholder can get if they sell one share.

So, let’s consider what happens after that action is performed. The shareholder now has $10 more money and one less share in the company. Likewise, the company has $90 in equity and 9 total shares. As it turns out, the price of one share is still $10, since $90 / 9 = $10.

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Great Digi-Key article on FPGAs, and reflection on PLD design

quorten

2020-02-24

Categories: raspberry-pi  
Tags: raspberry-pi  

This is a great Digi-Key article on FPGAs that really helps to clear up the basic terminology behind the hardware specifications when you are shopping for a particular chip.

20200223/https://www.digikey.com/en/articles/techzone/2019/nov/fundamentals-of-fpgas-what-are-fpgas-and-why-are-they-needed

So, one thing that I must say about programmable logic devices. When should you use these versus a small soldered constellation of logic ICs? Here’s my advice I’ll put in. If you only have a really small and simple logic network, go with the ICs and wire soldering, because ultimately this will be easier to debug if issues arise in the “programming” of such a network: just check the wire connections. On the other hand, if you use a Programmable Logic Device (PLD), that would make the soldering job easier, but if anything goes wrong with the internal memory, then that’s much harder to debug and diagnose. Especially if the intent is to never reprogram the chip in the final design and there are no programming connections to the CPU. Which, of course, for simple such networks, there isn’t a need to reprogram.

So, yes, the point is that you should only use a PLD when the degree of complexity really warrants it in order to save cost, save space, have a clean wiring scheme, and so on.

Finally found the tricks of the trade behind crimping Molex PicoBlade

quorten

2020-02-24

Categories: raspberry-pi  
Tags: raspberry-pi  

A few months back, I bought some Molex PicoBlade housings and pins but no means to crimp them. Many times I was searching for more information on crimping them, but haven’t quite found what I needed. But now, I finally found what I was looking for. An affordable, universal crimping tool for micro connectors.

What is the general name of the game? Generally, “trapezoidal crimping” tools are what you can use for crimping connectors similar to Molex PicoBlade. Here is a variety of oversized crimping tools inside this product catalog, for example.

20200223/https://media.digikey.com/pdf/Data%20Sheets/American%20Electrical%20PDFs/Full%20Line%20Catalog.pdf

So, here’s my deal pick, the Engineer PA-09. Great price and relatively easy to use. That expensive Molex tool that is recommended in the Digi-Key links? That is the “production-grade” tool for making lots and lots of crimps quickly and efficiently, hence the higher price tag, not to mention the higher need for lubrication maintenance on that more complex tool.

Read on →

Technicolor revisited

quorten

2020-02-22

Categories: media-prog  
Tags: media-prog  

Two-strip Technicolor… how exactly does that work? How were those films able to get the range of whites and blacks that they did with only two colors? The answer is a tricky one. Ultimately, experimentation was used to pick the particular color primary values that would get pretty good results given the limitations of using only two primary colors.

First of all, let’s evaluate the bare minimal extreme where only the lowest quality is achieved. Additive color with only red and green will only give you a range of colors from black, red, yellow, and green. You will not be able to achieve pure white because of the lack of a blue component. Thus, all images will generally be tinted yellow.

Again, please note that I am generating these color displays in a gamma-correct fashion, using gamma = 2.2 rather than full sRGB for simplicity.

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Does depression have a heritable advantage?

quorten

2020-02-22

Categories: twitter   random  
Tags: twitter   random  

Interesting articles I’ve found here referenced from discussion on Twitter. Does depression have a heritable advantage? Interestingly, some of the genes that cause depression also seem to have an effect on strengthening the effectiveness of the immune system. In the old days, any cuts or wounds would almost certainly result in infection, and without modern medicine, that would very likely result in death. But, the alterations in the immune system caused by the same genes that caused depression strengthened the body’s ability to fight off infections, if not also causing changes in the brain that would completely avoid situations that would likely result in infection.

In modern times, however, infection is not at all an issue to treat with modern medicine, so the tables are turned.

20200221/https://www.theatlantic.com/health/archive/2012/10/the-evolutionary-advantage-of-depression/263124/
20200221/https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2989690/

GitHub transparency report, and weakening reports from other companies

quorten

2020-02-22

Categories: legal   license  
Tags: legal   license  

Once again, GitHub publishes its annual transparency report. However, interestingly, they note that the practice is becoming sparser as other companies are retiring their transparency reports. That’s unfortunate, but as the Atlantic news article says, when the interest of the “general public” in privacy matters wanes as the news of the Snowden leaks fades, it’s pretty hard to encourage business executives to keep at the public publications of transparency reports.

20200221/https://github.blog/2020-02-20-2019-transparency-report/
20200221/https://www.theatlantic.com/technology/archive/2019/09/what-happened-transparency-reports/599035/

One thing I must say about the GitHub transparency report itself, though, is that even that appears to be less detailed.

Escape sequences in YAML multiline strings

quorten

2020-02-21

Categories: misc  
Tags: misc  

Okay, so now here is a tip on a tricky aspect of YAML syntax. How do you create a multiline string in YAML that has backslashes and does not end with a newline? Within a multiline string using either the | or > character to indicate it, backslashes do not start escape sequences, they are represented literally. Now, if you don’t want there to be a trailing newline, you use |- as your indicator character sequence.

20200221/https://en.wikipedia.org/wiki/YAML
20200221/DuckDuckGo yaml multiline strings escape sequences
20200221/https://yaml-multiline.info/
20200221/https://yaml.org/spec/1.2/spec.html/#id2794534

Useful Puppet check tool

quorten

2020-02-21

Categories: misc  
Tags: misc  

Want to do a Puppet lint quick on a local repo? Try this Puppet check tool that is relatively easy to install.

20200221/https://github.com/mschuchard/puppet-check