CN204442293U - A kind of selective frequency amplifier circuit - Google Patents

Abstract

The utility model relates to ultrasonic flow meter technology field, especially a kind of selective frequency amplifier circuit.It comprises receiving transducer, intermediate frequency transformer, the first limiter diode, the second limiter diode, the first resistance, the second resistance and capacitor; Described first resistance, the first limiter diode and the second limiter diode are all parallel to the two ends of receiving transducer, described second limiter diode is parallel to the primary side of intermediate frequency transformer, described capacitor is parallel to the primary side of intermediate frequency transformer, and described second resistor coupled in parallel is in the two ends of capacitor.The utility model take intermediate frequency transformer as core, the small-signal that receiving transducer receives can be carried out to He Ne laser and once amplifies, the noise outside filtering tranmitting frequency certain limit, and useful signal is amplified to degree such as being beneficial to later stage signal transacting; Its structure is simple, has very strong practicality.

Description

A kind of selective frequency amplifier circuit

Technical field

The utility model relates to ultrasonic flow meter technology field, especially a kind of selective frequency amplifier circuit.

Background technology

Operationally, ultrasonic signal is emitted in fluid by the transmitting transducer be attached in fluid pipe walls ultrasonic flowmeter, and receiving transducer is delivered to post-module after receiving the ultrasonic signal through fluid carries out subsequent treatment.The signal amplitude received due to receiving transducer is less, makes signal in communication process, very easily be subject to the interference of external environment noise, circuit noise, power noise etc.

Therefore, be necessary to provide a kind of circuit structure, the signal that can receive the receiving transducer of receiving transducer carries out filter amplifying processing in advance, thus ensures the functional effect of whole flowmeter.

Utility model content

For above-mentioned the deficiencies in the prior art, the purpose of this utility model is to provide a kind of circuit structure simple selective frequency amplifier circuit.

To achieve these goals, the utility model adopts following technical scheme:

A kind of selective frequency amplifier circuit, it comprises receiving transducer, intermediate frequency transformer, the first limiter diode, the second limiter diode, the first resistance, the second resistance and capacitor;

Described first resistance, the first limiter diode and the second limiter diode are all parallel to the two ends of receiving transducer, described second limiter diode is parallel to the primary side of intermediate frequency transformer, described capacitor is parallel to the primary side of intermediate frequency transformer, and described second resistor coupled in parallel is in the two ends of capacitor.

Owing to have employed such scheme, the utility model take intermediate frequency transformer as core, the small-signal that receiving transducer receives can be carried out He Ne laser and once amplified, the noise outside filtering tranmitting frequency certain limit, and useful signal is amplified to degree such as being beneficial to later stage signal transacting; Its structure is simple, has very strong practicality.

Accompanying drawing explanation

Fig. 1 is the circuit structure diagram of the utility model embodiment.

Embodiment

Below in conjunction with accompanying drawing, embodiment of the present utility model is described in detail, but the multitude of different ways that the utility model can be defined by the claims and cover is implemented.

As shown in Figure 1, a kind of selective frequency amplifier circuit that the present embodiment provides, it comprises receiving transducer R, intermediate frequency transformer T2, the first limiter diode D1, the second limiter diode D2, the first resistance R1, the second resistance R2 and capacitor C; Wherein, first resistance R1, the first limiter diode D1 and the second limiter diode D2 are all parallel to the two ends of receiving transducer R, second limiter diode D2 is parallel to the primary side of intermediate frequency transformer T2, capacitor C is parallel to the primary side of intermediate frequency transformer T2, and the second resistance R2 is parallel to the two ends of capacitor C.The circuit of the present embodiment can carry out He Ne laser and once amplifies the small-signal that receiving transducer R receives, the noise outside filtering tranmitting frequency certain limit, and useful signal is amplified to degree such as being beneficial to later stage signal transacting; It is with intermediate frequency transformer T2 for core, and intermediate frequency transformer T2 realizes impedance matching at this, signal amplifies and filtering, and by rotating the magnetic cap of intermediate frequency transformer T2, makes capacitor C parallel resonance, to reach the object of frequency-selective filtering.

Meanwhile, the first limiter diode D1 in circuit and the second limiter diode D2 plays the effect of amplitude limit, with the noise signal of filtered signal amplitude beyond positive and negative 0.3V, prevents large-signal from after amplifying, affecting subsequent conditioning circuit and normally works; Second resistance R2 then plays at this effect regulating bandwidth, and from the principle of parallel resonance, the quality factor q of this circuit can represent with following formula:

$Q=\frac{\mathrm{wL}}{R_2}=\frac{1}{w{\mathrm{CR}}_2}$

Therefore, when the prevention of reduction second resistance R2, the quality factor q value of circuit increases, and circuit frequency-selecting bandwidth reduces, and filtering characteristic strengthens.

The foregoing is only preferred embodiment of the present utility model; not thereby the scope of the claims of the present utility model is limited; every utilize the utility model specification and accompanying drawing content to do equivalent structure or equivalent flow process conversion; or be directly or indirectly used in other relevant technical fields, be all in like manner included in scope of patent protection of the present utility model.

Claims (1)

1. a selective frequency amplifier circuit, is characterized in that: it comprises receiving transducer, intermediate frequency transformer, the first limiter diode, the second limiter diode, the first resistance, the second resistance and capacitor;

Described first resistance, the first limiter diode and the second limiter diode are all parallel to the two ends of receiving transducer, described second limiter diode is parallel to the primary side of intermediate frequency transformer, described capacitor is parallel to the primary side of intermediate frequency transformer, and described second resistor coupled in parallel is in the two ends of capacitor.