Control circuit for an indicating device

Claim 1

IN A SIGNAL CONTROL CIRCUIT FOR USE IN NAVIGATING A MOBILE CRAFT, AN INDICATOR DEVICE HAVING A FIRST AND SECOND TERMINAL, MEANS FOR CONNECTING SAID TERMINAL TO GROUND, A VOLTAGE LIMITER INCLUDING A FIRST AND SECOND DIRECT CURRENT POTENTIAL SOURCE, A FIRST AND SECOND POTENTIOMETER ELEMENT, AND A THIRD TERMINAL CONNECTED IN SERIES IN SUCH A MANNER THAT THE FIRST AND SECOND DIRECT CURRENT POTENTIAL SOURCES ARE IN THE SAME POLARITY AND SAID THIRD TERMINAL IS LOCATED BETWEEN SAID FIRST AND SECOND POTENTIOMETERS, A FOURTH TERMINAL, FIRST AND SECOND UNILATERAL IMPEDANCE DEVICES, MEANS FOR CONNECTING SAID FIRST UNILATERAL IMPEDDANCE DEVICE BETWEEN SAID FIRST POTENTIOMETER AND SAID FOURTH TERMINAL AND SAID SECOND UNILATERAL IMPEDANCE DEVICE BETWEEN SAID SECOND POTENTIOMETER AND SAID FOURTH TERMINAL SO THAT SAID FIRST AND SECOND UNILATERAL IMPEDANCE DEVICES ARE IN INVERSE POLARITY, MEANS FOR CONNECTING SAID THIRD TERMINAL TO THE FIRST TERMINAL OF SAID INDICATING DEVICE, A SOURCE OF SIGNALS REPRESENTATIVE OF NAVIGATION FUNCTIONS OF THE CRAFT, MEANS FOR CONNECTING THE OUTPUT OF SAID SOURCE OF SIGNALS TO SAID FOURTH TERMINAL AND MEANS FOR APPLYING OTHER SIGNALS OF SAID SOURCE OF SIGNALS DIRECTLY TO THE FIRST TERMINAL OF SAID INDICATING DEVICE.