Rebuilding the Past: A 30 MHz TTL Frequency Counter from the 1978 MHSZ Design

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

Inductance Meter Adapter

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

Experiments with a Plasma Globe

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.

How to Make Invisible Ink

People have been sending secret messages since ancient times. Countless methods have been devised to protect information—and just as many to uncover it. Nowadays, digital methods are in fashion, and ciphers and chemical inks are more like toys, but there was a time when lives depended on them. Methods for concealing information fall into two … Read more