Abstract: A digital fuel control system for a small internal combustion engine having a pressure sensor for detecting the instantaneous pressure in the air intake manifold of the engine to generate air pressure data. A microprocessor responsive to the air pressure data generates a fuel quantity output signal indicative of the quantity of fuel to be delivered to the engine. A fuel metering apparatus responsive to the fuel quantity output signal generated by the microprocessor meters the fuel being delivered to a fuel delivery mechanism which delivers the fuel into the air intake manifold of the engine. The microprocessor in response to the air pressure data generated by the pressure sensor determines the engine's speed and the average pressure of the air inhaled by the engine. The engine speed data and air pressure data address a look-up table to extract data indicative of the fuel requirements of the engine.

Abstract: A null adjustable vortex rate sensor which enables the precise control and elocation of the stagnation point of the fluid stream with respect to the null line of the pickoff located within said chamber. The null adjustable vortex rate sensor is a vortex rate sensor with a fixed position pickoff and a fixed position drain, a rod being concentrically located in the drain and extended from the drain into the chamber. The horizontal adjustability of this rod inside the drain controls the location of the stagnation point at the pickoff within the chamber very precisely thus enabling one to approximately choose the location of the pickoff member and by means of the rod mechanism located in the drain move and adjust the stagnation point to obtain a null output at the fixed position of the pickoff. The pickoff provides a differential pressure signal which is a function of the angular rate of rotation of the chamber in inertial space.