In 2009, Bulgarian Anton Orush started his collection dedicated to Bulgarian technology. 

The exhibits include televisions, radios, appliances, computers, telephones, cash registers, etc. Gradually, this passion of his led him to start researching and retrieving artefacts representing the entire technical history of Bulgaria. Two editions are the result of his research - "A Big Book on Bulgarian Technology" and "Made in Bulgaria 101 Bulgarian Mechanical Products". The latter contains some new finds in his collection, acquired in the last 3-4 years, but also tells about other interesting facts and inventions. Among them are the first Bulgarian electric bus, the first Bulgarian light bulb factory in the Principality of Bulgaria and many more.

There is also information about the filton, a musical instrument created by teacher Lyuben Istatkov:

"As he himself said, he wanted to make an instrument in which each note would produce a corresponding sound, so that the pupil could get not only an auditory but also a visual idea of the tones - researcher Anton Orush tells Radio Bulgaria. - In the summer of 1940, Istatkov drew a blueprint of a new string instrument, which resembled a large counting frame like those once used by children in schools. 

The filton has a resonator, the two plates of the resonator being connected by a slat which transmits the vibrations from the upper plate to the lower plate of the resonator. A fret is placed on the upper board so that the strings do not rest against the board but vibrate freely. The strings are tuned so that their range is from G below the staff to F above the staff. Opposite the upper board of the resonator is another board, on the face of which is a staff with notes cut out. These are also the keys, and on the back of the board is the electrical part of the filton: the electromagnets. The anchors of the electromagnets are set back 8 mm from the strings. The magnets are powered by a pair of 4.5V batteries placed on the floor next to the filton stand, with one battery pole connected to the electromagnets and the other to the corresponding key. When a key is pressed, the circuit is closed - the peg hits the corresponding string, producing the desired sound. According to its inventor, the sound of the filton is similar to that of a mandolin, but deeper and purer.

Anton discovered the information about the instrument by chance when a local expert from the Montana region contacted him and gave him a letter that the teacher had sent to the editor of a newspaper. In it, he described the construction and operation of the instrument, hoping to draw attention to his invention. But this never happened. Nor did anyone in Sofia pay any serious attention, as the Second World War had already begun. 

In the 1960s, Bulgaria saw the emergence of a number of new electrical appliances and equipment designed to facilitate work in various spheres of life. Among them, of course, was agriculture, where an "innovative" electric tractor appeared to help farmers: