PURPOSE: To obtain an inexpensive digital output flowmeter having simple structure with large and small diameters, by constituting the flowmeter by an electrically insulated electrode, which is fixed to a position, where Karman vortexes that are yielded at the downstream of nonstreamlined body pass or at a position where fluid vibration is present, and a grounding electrode, which determines the potential of the fluid.

CONSTITUTION: A brass vortex generator 11, which is fixed in a brass body 10, constitutes a nonstreamlined body. A fixed electrode 12 is fixed at a position where Karman vortexes that are yielded at the downstream of the brass vortex generator 11 pass or at a position where fluid vibration caused by the vortex is present. The electrode 12 is electrically insulated with respect to the brass body 10 and the brass vortex generator 11. A current should flow between the electrode 12 and a grounding electrode for determining the potential of the fluid. Therefore it is necessary that an insulating film is not formed on the surface by the fluid 7 for relatively short time, and the electrode is not corroded. Then the electrode is plated by an insoluble metal. In a flow rate transmitter constituted in this way, a voltage is applied across the fixed electrode 12 and the grounding electrode. The change in current when the fluid between both electrodes is vibrated by the vortexes is detected, and the flow rate is found.