?????? ?????? ?? ????? ??????? ?? ????? ??????? ????? ???????? ??? ?????? ?????? ??? ?????? ??????????.?????? ??? ???? ??????? ??????? ??? ?????? ?? ????? ??????.??????? ??????????? ????? ?????? ???? ???????? ???? ???????? ??????????????? ????? ??????? ??????????? ?????? ?????? ?????Vacuum tubes (thermionic valves) had been the very first active D