Saving Solitary Bees: The Right Way to Create a Bee Hotel

In the spring of 2019, I wrote an article about the so-called “wasp garage,” prompted by the fact that these things started appearing in many supermarkets and pet stores. Lots of people bought them, put them out in their gardens—and nothing happened. NGOs and local governments also installed them in public spaces, and there are … Read more

ВСА-5К (VSZA-5K) Soviet battery charger

I inherited this device from my father—he brought it from the Soviet Union at some point. It was manufactured in 1974 and is a typical example of the simple yet extremely robust Soviet devices. It doesn’t contain any “smart” electronic circuits, so there’s nothing in it that could burn out or break. It’s simply built … Read more

Sustainable Thermal Water Resource Management in the Budapest Agglomeration

It is well known that, thanks to its favorable balneological and geothermal conditions, Hungary is a country rich in thermal waters. Although the demand for the energy utilization of thermal water is increasing, geothermal energy remains our largest untapped energy source, due to the unique geological characteristics of the Carpathian Basin. The average domestic heat … Read more

My Little Airshow Radio

Spotters, SWL (shortwave listening) enthusiasts, and amateur radio operators all enjoy listening to aircraft communications — and nowadays, even drone pilots find it useful to monitor air traffic. A good handheld airband transceiver easily costs well over a hundred thousand forints, whereas the device described here is dirt cheap by comparison. Of course, it’s not … Read more

Vintage Pocket Voltmeter

The handheld meter has been a staple in almost every technician’s toolkit for nearly 100 years. Today, the majority of handheld meters have digital displays. However, until the 1970s, most meters featured analog readouts. These were typically multimeters capable of measuring voltage, current, resistance, and occasionally capacitance and frequency. “Pocket watch”-style measuring instruments were popular … Read more

1.3 GHz 1:1000 Frequency Counter Prescaler

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

Can You Trust Your Voltmeter?

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

Mini Lab Power Supply: 1.3–33 V DC, 14 V AC, 1.1 A

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

Should We Fuel Up with E10?

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

Vostok TOZ–35 Free Pistol

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