A motley collection of ideas
Homemade circuits, experiments, tinker-friendly electronic ideas, and and things related to amateur radio.
You know that old Hofi Géza joke about “if you don’t have an aquarium…”? Well, I do have an aquarium. It has been fitted with 12 V LED lighting for quite some time. And there was a small problem with it. When a DC Connector Starts Getting Warm The lighting cable had a conventional round … Read more
I came across the printed circuit board for this circuit completely by accident. It looked like an interesting and clever little design, and I had more than enough suitable parts lying around in my component drawers, including a pile of spare relays. So I decided to build one and measure what it could actually do. … Read more
This time, the device on the teardown bench is not broken. My Radtel RT-470 is fully functional and gets regular use; it simply needed a thorough cleaning. For that reason, I did not take it apart any further than what you can see in the photographs. Even so, there is plenty to discover about how … Read more
The module shown in the picture can be purchased online for around 2–3 euros. It is a small “15 kV” generator suitable, for example, for secondary-school science experiments or for use as a negative ion generator/air ionizer. The circuit can produce a stable, high-temperature, high-frequency arc, which can easily ignite small combustible materials, such as … Read more
The meteorological radiosonde is an interesting creature. It sets off from somewhere beneath a large white balloon, measures the atmosphere’s temperature, humidity, pressure and GPS coordinates, and then, when the balloon bursts, the instrument descends to the ground. For meteorologists, the story more or less ends here; for radio amateurs and radiosonde hunters, however, this … Read more
The device shown in the picture is the NZ-1 hand winding machine: a simple mechanical tool used to wind neat coils from wire, thin electrical conductor, or other filament-like material. It is not an automatic wonder machine, nor a CNC-controlled industrial device, but a cheap Chinese gadget. I bought it for about 30 euros. Its … Read more
The literal English translation of the Hungarian phrase “DVD-játékos” would be “DVD gamer,” which does not mean some bloke raised on the game consoles of the 2000s who insists on physical discs. Rather, people jokingly used it for a “DVD player” because, years ago, the machine-translated Hungarian user manual of a Chinese device — later … Read more
Among radio amateurs – especially abroad – fox hunting is still a fairly popular sport today. Here I present a simple fox‑hunting setup that can be used at home, in the garden, for play, for tracking animals, or even for hunting “flying foxes”. “Fox hunting”, or radio orienteering (Amateur Radio Direction Finding – ARDF, also … Read more
Every day, dozens of tiny, invisible instruments rise above our heads. Weather radiosondes that collect data from the lower and upper layers of the atmosphere, then a few hours later quietly disappear somewhere above fields, forests, and villages. The signals from these sondes can be received by anyone — and that’s where the exciting world … Read more
I wanted a simple, inexpensive antenna for my Little Airshow Radio. The 108–137 MHz range is the VHF airband, where the wavelength is roughly 2.18 m to 2.73 m. That means any resonant antenna designed for this range tends to be physically large. If you’re looking for a small, portable solution, you’ll need to make a few compromises. … Read more