Abstract: A device for monitoring and/or measuring the flow velocity of a flowing fluid comprises temperature sensing means adapted for location in said flowing fluid. The sensing means comprises two identical monolithic semiconductive crystals (integrated circuits) each arranged in a heat conducting case. Each crystal contains a number of series connected diode paths serving as temperature sensors. One of the crystals in addition includes a heating member, such as a semiconductor device having a diode, transistor or Zener diode characteristic with a low temperature coefficient. A constant voltage is supplied to said heating member thereby developing constant power, and thus a constant temperature rise, in said one crystal over a large temperature range. Means are arranged for supplying current in the forward direction in the two diode paths, and a comparison circuit is connected to the diode paths for comparing the currents therein, whereby the flow velocity may be determined.

Abstract: From each of two AC input terminals, separate inductive sections are connected to the opposite sides of a capacitive portion, which in turn is connected to the output terminals. Each inductive section includes a controlled switching device connected in series with an inductive portion and a unidirectional conductive device connected in shunt with the series connected combination of the inductive portion and the switching device, the unidirectional conductive devices being oppositely poled with respect to currents passing from one input terminal to the other input terminal.