| 摘要 |
PURPOSE:To detect the flow-out of liquid in a detector by providing a three- way selection switch that shuts off an exciting circuit by means of giving a mimic signal that is synchronized with the exciting signal to the exciting circuit and providing a comparator that takes as a standard voltage the output of a converter at the time where there is a fluid. CONSTITUTION:A square wave exciting electro-magnetic flow meter converter consists of a high input impedance differential A/C amplifier 11, later stage amplifier 12 that processes the output by calculation. Further, a mimic signal generating circuit that consists of a switch 14 such as FET that is turned on and off in synchronization with the exciting signal, D/C standard voltage source 13, and resistor 15 for current limitation is provided. Also a 3-circuit select switches 19a-c and a comparator 21 are provided. The standard voltage 20 is established equal to the output value of an amplifier 12 that is obtained by input of a mimic signal when the switches 19a-c are operated and a fluid exists in the measurement pipe 3 and the output impedance of the electrode 4 is at maximum, and it is possible to make a comparator 21 sends a signal that indicates that there is no liquid in the measurement tube 3. |
