Slabotokov zavod; - Schwachstromwerk Sofia: genannt in "Geschichte der Rundfunkindustrie der DDR" (Hein) Seite 195 und "Funkamateur" Heft 10 / 1967. Zumindest Lizenzbauten und Nachbauten von Graetz-Geräten (Deutschland).

Known as manufacturer of TV sets as also Radios for export.

Weak-current factory "Kliment Voroshilov" In 1949, on the outskirts of Sofia, in periphery of the district "Sugar Factory" on the corn fields and urban landfill it was created an impressive plant that has an important role in the history of industrialization and development of Bulgaria. As an artificial conglomerate, it was gathered together all the equipment, facilities, machinery and staff at all major weak-current enterprises in the capital - the former: TT factory (Telephone-Telegraph factory) („ТТ фабрика”), "Radioprom" („Радиопром”), "Native Radio” („Родно радио”), " Ring " („Ринг”) and others. In it, have been developed and manufactured: - Radio; - Low frequency amplifiers; - TVs; - Electric gramophones; - Transmitters; - HF and VHF radiostations; - Manual and automatic telephone exchanges; - Telephones; - Electrometers and other electrical measuring appliances; - X-ray equipment; - Medical equipment for physiotherapy; - Radio-relay equipment; - Sealing phone systems; - Radio components and units for the production of the listed nomenclature - resistors, potentiometers, capacitors, relays, magnets, speakers and more.