Wondering about what those weird safety symbols you might see mean? Here we go, what I was wondering about was the GHS hazard pictograms.
20200728/https://en.wikipedia.org/wiki/GHS_hazard_pictograms
Drag soldering, liquid flux is a must-have. Sure it is, but what kind? Well, that was a tough question to answer from the looks at fist, but now, the answer is clear. If you want to solder small, miniaturized, high-density electronics, then no-clean flux is your go-to kind of flux, especially if you are doing new board work rather than repair on old boards. Okay, that makes the decision really easy for the sake of my own projects.
20200728/DuckDuckGo what kind of flux works best for drag soldering
This website also has a lot of other great information on your choice of solder flux. In particular, when working on old boards, you should use Rosin Activated (RA) flux because the stronger flux will more quickly clean away oxides that have built up on the board.
20200728/https://www.pcbtoolexpert.com/the-top-5-best-flux-pens/
Another good point mentioned in the article. Do you need flux to solder? If you want to do soldering right, yes. Otherwise, you will vaporize metal oxides, and trust me, you don’t want to be breathing those in. Yes, that’s interesting that flux helps prevent metal oxides from going airborne.
Wait, what? I heard mention of making your own solder flux? Okay, okay, let’s see how that works.
Sure, I’ve already taken notes on cleaning soldering iron tips, but I feel I need better notes. So, here we have it, better info to our avail, from Weller.
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Cleaning your soldering iron tip with a wet sponge puts stress on the tip due to the thermal expansion and contraction, it causes metal fatigue that can cause it to fail earlier. It’s therefore better to use brass wool (softer), or steel wool (a harder abraisive on the tip, it can wear out the tip but the wool lasts longer).
That being said… I’ve noticed that you can use a dry paper towel for cleaning solder tips, if you only need to clean off mild oxidation on the tinned surface. Just don’t hold the solder tip on the same position too long otherwise it will char the paper towel.
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Avoid using liquid flux directly to clean the tip because it is corrosive. Especially, do not use water-soluble fluxes because they can damage the tip at high temperatures. Additionally, using water-soluble flux for touch-up work will also hasten tip failure.
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If a little oxide has built up on the tip, you can use rosin-activated core solder to get it off. The stronger flux is required, no-clean flux will not clean the oxide off the tip.
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Again, tip reactivator is a last resort if all else fails.
20200728/DuckDuckGo clean solder iron tip flux
20200728/https://www.weller-tools.com/how-to-care-for-soldering-iron-tips/
This is an interesting article, analyzing GPT-3 against a Turing Test. It does quite well, and proves hard to beat. One thing that is obvious is that the intelligence is very capable in general, but its range of responses to the Q & A test is over-constrained by the example prompt, causing it to fail at some challenges that it can easily pass when given a different prompt.
20200728/https://lacker.io/ai/2020/07/06/giving-gpt-3-a-turing-test.html
That being said, a few obvious and undeniable weaknesses are worth pointing out. Very straightforward, rational, quantitative, and logical reasoning questions cannot be accurately answered. For example, answering questions about the relative weight of objects, it does well most of the time but it has a few notable failures. And, performing arithmetic and simple list manipulations, the AI totally falls on its face when prompted with this. On the other hand, the AI shows that it is curiously good at converting English descriptions of computations to Ruby and Python programs that go and do likewise.
So, that being said, let me put in my own reflection. Unfortunately, the state-of-the-art of artificial intelligence has become a precise mirror of our own human weaknesses. Humans, on the mass market general average, are excellent at generating entertainment materials like fiction novels and “fake news,” but they suffer greatly when it comes to more precise, quantified, organized tasks. Why? It’s simply due to a lack of motivation. Humans don’t want to do quantitative reasoning. It’s not that they can’t do it, it’s that they don’t want to do it.
Interesting article here about falsehoods programmers believe about names. Gosh, this makes it really tough to program basic applications if you can’t assume there is one, consistent, unique name string.
20200728/https://www.kalzumeus.com/2010/06/17/falsehoods-programmers-believe-about-names/
Can’t get people to properly report environmental changes in an organized manner? Unfortunately, this is a generally understood fate in the human world at large. The plug is that there is a “technological fix.” In the real estate world, this is by using surveying airplanes, run by unorganized commercial parties that are in the market to compete with each other on data portfolios. Never mind that there is redundancy.
20200728/https://www.cnbc.com/2016/08/31/how-a-low-flying-spy-plane-is-setting-your-apartment-rent.html
Okay, okay, I still don’t understand how stock share prices are calculated. Calculating the net present value depends on all future dividend payouts? How can you do that since that’d be an infinite quantity? The idea, simply put, is by assuming that a company has zero growth or negative growth over long periods of time, the cash flow value would be constant, but the time value of money would diminish and eventually drop to almost zero, assuming steady positive inflation. Obviously, now that I state these assumptions clearly, it should be understood that this, therefore, cannot be applied generally to all imaginable economies or quantities that can be reasonably treated as economic quantities.
But, given that key assumption, the otherwise infinite series can converge to a finite number. This is explained in Investopedia’s definition of a “perpetuity.” So, now that you understand that, we can get a bit more technical on the real dynamics of the stock market. It turns out that the real listed share price is not actually calculated as such per se. The prime exception is at a company’s initial public offering (IPO), when the initial share price is calculated precisely by the formula, that of using the net present value of all future dividend payouts. After that, the stock buys and sells start having an influence on the calculated value.
Wikipedia failed to sufficiently explain, so I went web searching elsewhere to find the answer.
pi-parport can’t be the only game in town for Raspberry Pi parallel
port interfaces, can it? Well, actually it is almost the only game in
town, but not quite. However, the “competitors” are all proprietary
developers, so they don’t really count. Here is yet another interface
HAT, but it also includes a serial port. Adding a single serial port,
within limits, isn’t too hard to do for pi-parport. It’s just that
we can’t have software control over all the RS-232 pins due to a
finite number of GPIO pins.
20200727/DuckDuckGo raspberry pi parallel port
20200727/http://shop.elesar.co.uk/index.php?route=product/product&product_id=76
20200727/http://shop.elesar.co.uk/index.php?route=information/information&information_id=4
Now, here is a really tricky one. Rather than attempting to be a
parallel port host, it is designed to be a parallel port
peripheral. Looking carefully, pi-parport is in fact almost
equipped to do just that, it just needs one more control output pin
broken out to the GPIO pin header, and then a simple control <->
status swapping “null modem” cable does the trick to complete the
hardware side. Software-side, that is trickier due to the need to
manipulate 5 control pins rather than only 4, for which an
incompatible extension must be added to pi-parport.
When the extra control pin is not needed, it is simply initialized to logic-level zero for ground, and then it appears as simply one of the unused grounded pins on the parallel port.
What are “totem-pole” outputs? Those are simply “fully buffered” outputs where an input signal is converted so that logic one is a path to the positive voltage source, and logic zero is a path to ground. As opposed to “open collector” or “open drain” logic where logic level zero is simply left “floating.” And a buffer is also a “push-pull amplifier.”
20200727/https://en.wikipedia.org/wiki/Push%E2%80%93pull_output
20200727/https://en.wikipedia.org/wiki/Open_collector
Looking for more guidance on perfboard assembly? Take a look at this project that shows a deep dive into building a logic circuit on perfboard. Yes, looking at the solder joints, there’s lots of imperfection, and finally when it comes to breaking out the final I/O connectors to your embedded computer, you have a “beanstalk” of vertical wires sprouting up in random places. However, unlike on my project, this developer did not use crimp-on connectors to provide a more clean break-out of the available signals. Oh, and yes, the developer also used a whole bunch of white wires rather than using colored wires throughout the entire assembly, though there were some colored wires. And, yes, when wires needed to be routed back to the perfboard, overlong wires were indeed used to make grabbing easier.
20200727/https://medium.com/@rxseger/building-a-4-bit-shift-register-from-7400-nand-gates-for-gpio-output-port-expansion-on-a-raspberry-5d6cee8a1291