A motley collection of ideas
The purpose of this project is to extend the range of an older (and more affordable) frequency counter into the VHF and UHF bands. The idea was inspired by an article published in Rádiótechnika (1990/7, pp. 341–342), although the original circuit was designed by Zeljko Bozic, S52ZB, and later published in a 2006 issue of … Read more
The Practical Electronics for Inventors, Fourth Edition, 4th Edition is a fully-updated, no-nonsense guide to electronics. It cover anything that you need to develop and construct your own gadgets. People often ask me about electronics, physics, and science, but I usually don’t like to answer directly. Instead, I prefer to hand them a book and … Read more
Sometimes I find myself wondering which of my portable digital voltmeters I can actually trust. The old 4½-digit M4650? The Fulke? Or the younger METEX? (Okay, I have one from Lidl too, but that’s not even a question.) Generally, they all show pretty similar values, and I rarely need better than 1–2% accuracy—but it still … Read more
I needed a compact power supply capable of providing roughly 5–20 V DC and 12–16 V AC. Because an AC output was required, I chose a conventional transformer—similar to those used in alarm control units and intercom systems. This project was inspired by the Chordless Lab Power Supply on Thingiverse. DC Section The DC side is quite simple: a … Read more
Back in early 2020, the media was buzzing with what we could call the E10 panic. Article after article warned that “the new fuel will ruin your ride.” For some reason, people seem to love being scared—apparently Hitchcock just doesn’t cut it anymore, and EU bureaucrats are now scarier than The Birds. Under the Kyoto … Read more
When a layperson first encounters the TOZ–35, two things immediately stand out. One is the sheer size of the firearm: the barrel length is 300 mm — almost rifle-like. The other is the massive walnut grip that completely envelops the shooter’s right hand. It has to be slipped on like a glove, providing a secure … Read more
The mildew stain is very ugly and does not come out of the clothes when washed. But things can be saved if you know how to do it!No need to throw away clothes with mould stains! Small mould stains can be removed at home, but if you have larger, stubborn stains, it’s worth going to a dry-cleaning specialist (if you can find one who still knows how). Be careful with the practices that are circulating on various gossip sites! The use of strong detergents in particular can easily lead to completely ruining an otherwise salvageable garment. And if the mould fungus has really got into the fibres of the cloth, there is no other way to help but with vinegar scissors…
The phenomenon of resonance has many examples in physics, engineering, and everyday life, and the reed frequency meter is one of them. Surprisingly, such instruments are still in use here and there, although they are certainly considered rarities today. I picked up this specimen, manufactured in 1961, for a few coins at a swap meet. … Read more
My better half has a weakness for weather stations, and she especially likes this old piece. It’s not particularly smart, not particularly pretty, but it has a “frog”, which makes up for everything. It’s a cheap LIDL model — even the first one we bought didn’t pick up the signal from the external sensor. They replaced … Read more
It’s well known that bats use their sonar to navigate their surroundings with remarkable precision. As part of this ability, they emit powerful ultrasonic sounds that are characteristic of each species. These sounds are inaudible to the human ear, but with a simple device, we can detect them — which can be great fun and … Read more