A motley collection of ideas
Homemade circuits, experiments, tinker-friendly electronic ideas, and and things related to amateur radio.
“It was still called broadcasting, and it cost a lot of money,When the first speaker excitedly sat down at the microphone.His ringing voice soared and flew far away,And in one listener, something responded:— The test was successful!”(LGT: The Radio) Today, digital technology is making its way into every area of communication and broadcasting. The crystal … Read more
This article revives a classic from Janusz Wojciechowski’s cult book Building Electronic Toys: a simple Hartley oscillator that does nothing—except beep endlessly. I once drove my father crazy with it and today it’s still a perfect tool for learning electronics. We explain how it works, show how to rebuild it, and explore Wojciechowski’s quirky ideas … Read more
The Grid Dip Oscillator (GDO) is one of the most important instruments for amateur radio constructors. It was primarily used for tuning resonant circuits, but with a bit of ingenuity, it has a wide range of applications. The following text introduces this instrument and some of its potential uses, without aiming to be exhaustive. I … Read more
Anyone even slightly familiar with electronics knows the NE555 IC. This almost iconic timer circuit was designed in the summer of 1971 by Hans R. Camenzind, a Swiss-born electrical engineer who taught at Northeastern University in Boston. Yes, we’re the same age! It’s not the “greatest” IC because it’s the largest in size or the … Read more
A friend of mine recently asked me about a gadget called the Power Factor Saver. It’s a small plug, barely larger than a typical power adapter or an old mobile phone charger. According to the article I linked earlier, the price is now, just for you, 9800 HUF (around €25), and “the Power Factor Saver … Read more
This is a simple TTL-based lab frequency counter I originally built decades ago. At the time, I was a young student with very limited resources. Commercial laboratory instruments were completely out of reach, so I had no choice but to build my own. The design came from the Hungarian Defense Sport Association (MHSZ, Magyar Honvédelmi … Read more
I built this inductance meter adapter a long time ago for use with a digital multimeter capable of frequency measurement. The basic idea came from an article published in Funkchau issue 1/1981. I slightly modified the original circuit and designed a new PCB. Of course, I no longer use this device for measuring coils today, … Read more
The magic plasma ball is a well-known decoration that used to be popular at parties and nightclubs. A simple structure on the surface, but the spectacular light effect is based on a very complex phenomenon. It can also be used to perform some interesting experiments to surprise your friends.