Electronic hybrid

Claim 1

An electronic hybrid circuit for connecting a signal transmitting circuit and a signal receiving circuit to a two-way signal transmission circuit, said circuit comprising: constant current supply source means for providing current supply terminals for connection to said two-way signal transmission circuit; a signal control transistor, a line balance load impedance connected in series with the current path of said signal control transistor, said current supply terminals connected across the series combination of said signal control transistor current path and said balance impedance; and a signal summation circuit having inputs connected respectively at opposite sides of the current path of said signal control transistor, said signal summation circuit includes a series impedance element in each of said inputs connected respectively at opposite sides of the current path of said signal control transistor and wherein said signal transmitting output of said summation circuit is formed by the junction of said two series impedance elements, the arrangement being such that with a signal receiving circuit connected to provide a control signal to a current control electrode of said transistor, and a signal transmitting circuit connected to receive an output from said signal summation circuit, signal voltages generated across the impedance presented to said supply terminals in response to receipt of signals by said two-way transmission circuit or transmission of signals from said signal receiving circuit are fed to said signal transmitting circuit via said signal summation circuit, the signal voltages generated by said signal receiving circuit being at least partially cancelled in the summation circuit by corresponding signal voltages generated in phase opposition across said line balance load impedance.