Band-pass filtering twin-coil four-wire system string wire self-excitation energizing circuit

Abstract

The invention discloses a band-pass filtering twin-coil four-wire system string wire self-excitation energizing circuit which comprises an induction coil, an excitation coil, a high gain differential operational amplifying circuit and a transistor constant current power amplifier circuit with adjustable current magnitude, wherein an active band-pass filtering circuit and an in-phase operational amplifying circuit are also connected between the high gain differential operational amplifying circuit and the transistor constant current power amplifier circuit. The active band-pass filtering circuit is inserted between the front differential operational amplifier and the rear operational amplifier, high and low frequency disturbance voltages are subjected to band elimination and cannot easily enter the rear operational amplifier, only a string wire frequency signal is subjected to 8-time amplification and enters a rear level, a constant-current positive feedback is produced for the excitation coil, a steel wire rapidly starts oscillation to form stable steel wire vibration, more vibration wire sensors are enabled to reliably work, the percent of pass of the sensors is improved, the trouble of replacing the sensor for dynamic balance is greatly reduced, the debugging is simple and feasible, and the problem which influences people for a long time is solved.

Description

technical field [0001] The invention relates to the field of vibrating wire sensors, in particular to a double-coil steel wire excitation circuit. Background technique [0002] The double-coil steel string excitation circuit (exciter) is a component used in conjunction with the double-coil self-excited vibrating wire sensor, which plays a key role in ensuring that the frequency of the sensor's vibrating wire can be measured. [0003] The technology related to this application is the invention patent application No. 2010100280536 "double-coil four-wire constant-current steel string self-excitation circuit" proposed by the inventor on January 8, 2010. The circuit includes: induction coil L1 and excitation coil L2, the two ends of the induction coil L1 are connected to the input end of the differential high-gain operational amplifier circuit IC through a pair of twisted pairs, the input end is connected to the resistance attenuation network, and the differential high-gain opera...

AI Technical Summary

Problems solved by technology

Some people try to increase the filter capacitance to weaken the high frequency, increase the coupling capacitance between the stages so that the steel string fundamental frequency signal can pass through smoothly, and increase the steel string fundamental frequency vibration amplitude induction signal to overcome the double frequency vibration. However, these measures It is also easy to cause low-frequency interference oscillations in a small number of other sensors, making these few sensors unusable; in order to make this part of the sensors also usable, it is necessary to reduce the filter capacitor and coupling capacitor. The two are contradictory, and it is difficult to take care of them at the same time.

So a lot of people have been trying to solve this problem but have not been able to

Images