A quite large collection of electronic receivers, amplifiers, transmitters, even special devices from the earliest (triode by Robert von Lieben) up through the most modern. Domestic items include an important collection of several tens of items with the brand name "Mars", manufactured in Prague during the years 1923-32. This collection also includes three special diodes made by prof. August Žáček, who discovered so-called electronic magnetron vibration on them in 1924.