Bi-directional signal detector with input/output isolation

Claim 1

Apparatus for detecting the magnitude and direction of D.C. signals comprising: I. A magnetically coupled oscillator including a. first and second D.C. power input terminals for connection to a D.C. power source, b. a transformer having a saturable core with winding means thereon, said winding means including signal input winding means and first and second power input windings, c. first and second electric valves, each having a control electrode, respective first and second main electrodes and adapted to be placed in either a conductive or a nonconductive state; d. first and second power input paths connected in parallel between said D.C. power input terminals for alternately effecting opposite directions of magnetic saturation in saId core, each power input path including in series a different one of said power input windings and the main current path of a different one of said valves, the power input winding in each path being connected between the valve in the path and said first D.C. power input terminal, the valve in each path being connected between the power input winding in the path and said second D.C. power input terminal; e. feedback means for applying feedback voltages induced in said transformer to the control electrodes of said valves concurrently in opposite polarity thereby to establish concurrent opposite states of conduction in the valves, each of said valves being arranged to transfer from one to the other of said conduction states in response to feedback voltages induced in said transformer upon each occurrence of saturation in said core; II. first path signal providing means coupled to the said first path at a point between the power input winding in that path and said second D.C. power input terminal for providing a first path signal representing the current in that path; III. second path signal providing means coupled to said second path at a point between the power input winding in that path and said second D.C. input terminal for providing a second path signal representing the current in that path; and IV. output signal providing means coupled to said first and second path signal providing means and responsive to said first path and second path signals for providing an output signal that is indicative of the direction and amplitude of net D.C. signal input applied to said signal input winding means.