????? ????????? ??????????: ????? ?????? ?????? ?????? ???? ?????????? ??? ????? ????? ????????? ???????? ??? ?? ????.????? ??? ????? ?? ????????: ???????? ???????? ????? ????? ??????To begin with these devices were big and complex. Following Lee de Forest invented the triode in 1907 steel detectors used vacuum tubes to work and became much more se