Transmitting over power lines

Claim 1

Apparatus for transmitting over power lines comprising, a source of a unipolar potential derived from electrical power on said power lines, a source of a modulating signal of carrier frequency for interrupting said unipolar potential at a rate corresponding to said carrier frequency, and means for coupling the interrupted unipolar potential to said power lines to provide a carrier signal of said carrier frequency on said power lines, said means for coupling comprising gated semiconductor switching means having gate electrode means and input and output electrode means in series with one of said power lines, gate resistive means connected between said input and gate electrode means, gate capacitive means connected between said gate electrode means and the other of said power lines, output transistor switching means connected to said input electrode means for selectively exchanging current with said gate capacitive means through said gate resistive means, input capacitive means coupled to said output transistor switching means for carrying a potential for slowly switching the latter amplifying means on, first and second input switching means responsive to said modulating signal coupled to said input capacitive means and rendered conductive during alternating contiguous time intervals at said carrier signal frequency for alternately charging and discharging said input capacitive means and thereby slowly switching on said switching off said transistor switching means whereby said gated semiconductor switching means delivers to said power line a slowly rising and falling current provided by said transistor switching means.