Techy odds and ends

I don't mean power banks in general, they're useful devices and I use a few myself. What I'm referring to specifically here is the type of power bank that includes a small solar panel on it to "charge" the power bank using nothing but light. These devices are actually quite dangerous, which explains why the only companies manufacturing them are brands, usually Chinese, with a brand name that looks like a Scrabble hand, who use the cheapest components possible. There's a reason why more reputable brands don't make these bombs waiting to explode. The capacity of the batteries is significant. OK, you can't always trust the published specifications of these things from less reputable brands, but even so, you're going to end up with a battery pack with a capacity of several thousand milliampere-hours. Let's assume we're working with a 20,000 mAh pack here. Let's also assume that the capacity that the manufacturer is boasting is actually hone...

Cheap and Cheerful and gets the job done. Edit 07-Aug-2023: 19 months after buying this robot and using it every few days, it is dead. Mechanical failure means that one of the wheels is no longer connected to the motor that drives it, so the robot basically goes round in small circles. If you're looking for a smart appliance with all the bells and whistles then this is not it, but it doesn't pretend to be it anyway. This is an entry-level vacuum cleaner robot that fumbles around more or less randomly, cleaning up whatever is in its path. The reason I bought this is because I wanted to see how well the technology coped with a small home on one floor that really is quite cluttered to be honest. If it doesn't cope well, then no great loss. If it does, then I know I can invest a bit more when this one comes to the end of its life. The robot comes with an infra-red remote control allowing you to access its basic features: auto clean, room clean, edge clean, spot clean an...

First of all, let's get one thing out of the way. It's a major thing that you always need to bear in mind when participating in social media in order to enjoy it safely. Your own safety is not the only thing that depends on this, that of your friends and family does, too. Social media is not a safe haven. There. I said it. Social media is open to anyone, not just the "good guys" like you and your friends. The "bad guys" are also out there and they gradually glean snippets of information from you and others that help them build up a profile allowing them to impersonate you, take over your social media account or even perpetrate identity theft. Any of the above can ruin your reputation and your credit rating and get you into trouble with the law if a crime is committed using your identity. That is, unless you deprive the bad guys of this information... Don't even feed them misinformation either because they can detect patterns in tha...

It's about a week since I bought one of these so I thought I'd jot down some of my first impressions of the timepiece. My overall impression is positive. There are a couple of negative points that I'll deal with but, on the whole, I like this watch. The build strikes me as being sturdy. There is no play in the crown or in the buttons and their operation is met with a reassuring amount of smooth friction. The mechanism for setting the watch is slightly unconventional but it actually makes sense. Most analogue watches with date usually allow you to set the date by pulling the crown out to a first position, and then to set the time by pulling the crown out to a second position. This watch does things slightly differently because it also has to allow you to calibrate the chronograph before you use it for the first time. With the crown in the first position you can zero the chronograph's minutes hand (10 o'clock dial) and you can set the date by rotating the h...

We've all seen those status updates from friends stating that they got 9 out of 10 answers right to a so-called impossible test claiming that " Nobody will get more than 60% of these right!" or something similar, haven't we? Let's look at how these things work, what they do and why they do it. Before going any further, help yourself to a decent dollop of cynicism or you're going to be very disappointed in social media. Remember the golden rule: if it looks too good to be true, then the chances are that it is not true. If there is the remotest possibility that something happening on social media could be something other than what it looks like, then it is not what it looks like and someone is trying to pull a fast one for profit in some way. Are the people setting these quizzes doing it out of the goodness of their hearts for the enrichment of the human race? Of course not. They're doing it to make money . So how do they make their money? What is their...

This is a little foray into number theory and presents one method of calculating the value of \(\pi\). It involves using a program to perform iterative calculations, so in order to minimise the impact of compounded rounding errors, it makes sense to use a computing device that operates with sufficient precision. I chose the SwissMicros DM42 for this because it uses Thomas Okken's Free42 Decimal under the hood, which offers around 34 digits of precision. The DM42 is also extremely fast, particularly so if connected to a USB port while operating because it more than triples the CPU clock compared to battery-powered operation. Back in 1735, the Swiss mathematician, astronomer (and a few other things besides) Leonhard Euler stated, and proved in 1741, that as the number \(n\) tends towards \(\infty\), the probability that two natural numbers \(a\) and \(b\) less than or equal to \(n\) are coprime, i.e. that \(a\) and \(b\) share no common divisor other than \(1\), tends towards ...