????? ????????? ??????????: ????? ?????? ?????? ?????? ???? ?????????? ??? ????? ????? ????????? ???????? ??? ?? ????.?? ???? ??? ??? ??????? ??????? ??? ????? ???????? ?????? ??????? ?? ?????? ??? ?????? ??? ??? ???????Initially these devices ended up enormous and sophisticated. After Lee de Forest invented the triode in 1907 metallic detectors us