Ground detecting device

A ground detecting device for a vehicle, craft, or the like, having a storage tank mounted on the vehicle, or the like, and equipment for selectively controlling the pumping of fluid into and out of the storage tank, said ground detecting device comprising

• a transformer having first, second and third windings, said third winding being electrically connected to ground;
• a jack electrically connected in shunt with said third winding;
• a prong electrically connected to the vehicle, craft, or the like, and cooperating with said jack, when inserted therein, to short-circuit said third winding to ground, said short-circuit having a short-circuit impedance resulting in a voltage differential at said second winding;
• a comparator amplifier having a sensing input electrically connected to said second winding and a reference input, said comparator amplifier having an output;
• an astable multivibrator having an output electrically connected to the reference input of said comparator amplifier and to said first winding and supplying a reference input signal thereto;
• said
• a relay having a relay energizing winding electrically connected to the output of said comparator amplifier and controlling the equipment for selectively controlling the pumping of fluid into and out of said storage tank whereby when said vehicle, craft, or the like, is short-circuited, so that static electricity is dissipated from said vehicle, craft, or the like, to ground, the short-circuit is reflected at the first winding of the transformer and produces a voltage drop between the reference input signal and the sensing input of said comparator amplifier, said voltage drop causing saturation of said amplifier resulting in energization of the relay energizing winding and operation of said equipment.