CN213521846U

CN213521846U - Input detection circuit for weak signal

Info

Publication number: CN213521846U
Application number: CN202022598053.1U
Authority: CN
Inventors: 王献伟; 徐东桂; 张文彬
Original assignee: Guangzhou Weide Electric Equipment Co ltd
Current assignee: Guangzhou Weide Electric Equipment Co ltd
Priority date: 2020-11-11
Filing date: 2020-11-11
Publication date: 2021-06-22
Anticipated expiration: 2030-11-11

Abstract

The utility model belongs to the technical field of detection circuitry, especially, relate to input detection circuitry of weak signal. The No. 1 pin of the optical coupler is connected with the third resistor and then connected with the power supply electrode; the No. 2 pin of the optical coupler is connected with the collector of the triode; the base electrode of the triode is connected with the first resistor and then connected with the weak signal input end; a second resistor is connected in parallel between the base electrode and the emitting electrode of the triode, and the emitting electrode of the triode is grounded; the No. 3 pin of the optical coupler is grounded; no. 4 pin of optical coupler is connected with signal output part, resistance four respectively, and the other end of resistance four is connected with the power supply, and wherein, signal output part is connected with basic detection circuitry's input. The transistor can connect a weak voltage signal to the base of the triode and convert the weak voltage signal into a strong voltage signal, can realize that the weak current controls a large current to drive the TTL chip, and can not influence the input frequency of the signal.

Description

Input detection circuit for weak signal

Technical Field

The utility model belongs to the technical field of detection circuitry, especially, relate to input detection circuitry of weak signal.

Background

Because the need of testing sometimes needs to detect some external weak current signals, and because the signals are very weak, the signals are easily affected by the outside or the detection is not qualitative due to insufficient driving capability; the external input electric signal is directly input into the TTL level conversion chip, and the opposite level signal is output.

However, it should be noted that the input low voltage signal cannot drive the TTL chip, and if the current is too weak, the TTL chip cannot drive the TTL chip, so the low voltage signal cannot be output. Referring to fig. 1, TTLx is an externally input signal, and if the current driving capability is not sufficient, the voltage cannot be output at the MCU-TTL-IN-X terminal.

SUMMERY OF THE UTILITY MODEL

Aiming at solving the problems of the defects and the shortcomings of the prior art; an object of the utility model is to provide a simple structure, reasonable in design, convenient to use's weak signal's input detection circuitry, it can be received the base conversion of triode to weak voltage signal and become strong voltage signal, just can realize that weak current control heavy current comes the drive TTL chip to can not influence the input frequency of signal.

In order to achieve the above object, the utility model adopts the following technical scheme: the device comprises an optical coupler, a resistor I to a resistor IV, a triode and a basic detection circuit; the No. 1 pin of the optical coupler is connected with the third resistor and then connected with the power supply electrode; the No. 2 pin of the optical coupler is connected with the collector of the triode; the base electrode of the triode is connected with the first resistor and then connected with the weak signal input end; a second resistor is connected in parallel between the base electrode and the emitting electrode of the triode, and the emitting electrode of the triode is grounded; the No. 3 pin of the optical coupler is grounded; no. 4 pin of optical coupler is connected with signal output part, resistance four respectively, and the other end of resistance four is connected with the power supply, and wherein, signal output part is connected with basic detection circuitry's input.

Preferably, the basic detection circuit A consists of a TTL chip, a capacitor I to a capacitor IV and a resistor eleven to fourteen; a first capacitor, a second capacitor, a third capacitor and a fourth capacitor are respectively connected in parallel between each input end of the TTL chip and the grounding end; and each output end of the TTL chip is respectively connected with the eleventh resistor, the twelfth resistor, the thirteenth resistor and the fourteenth resistor in series and then output.

Preferably, the conduction rate of the optical coupler is matched with the frequency of the input signal.

Preferably, the TTL chip is a 74HC14D singlechip.

After the structure is adopted, the utility model discloses beneficial effect does: the transistor can connect a weak voltage signal to the base of the triode and convert the weak voltage signal into a strong voltage signal, can realize that the weak current controls a large current to drive the TTL chip, and can not influence the input frequency of the signal.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the present invention is described in detail by the following specific embodiments and the accompanying drawings.

FIG. 1 is a drawing of the background art of the present invention;

FIG. 2 is a schematic structural view of the present invention;

description of reference numerals: an optical coupler OP1, a resistor one to four R1-R4 and a transistor Q1.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described below with reference to specific embodiments shown in the accompanying drawings. It should be understood that the description is intended to be illustrative only and is not intended to limit the scope of the present invention. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present invention.

It should also be noted that, in order to avoid obscuring the invention with unnecessary details, only the structures and/or process steps that are closely related to the solution according to the invention are shown in the drawings, while other details that are not relevant to the invention are omitted.

Referring to fig. 2, the following technical solutions are adopted in the present embodiment: the circuit comprises an optical coupler OP1, resistors from one resistor to four resistors R1-R4, a triode Q1 and a basic detection circuit A; the No. 1 pin of the optical coupler OP1 is connected with a resistor three R3 and then connected with a power supply electrode SVCC 1; pin 2 of the optical coupler OP1 is connected with the collector of a triode Q1; the base electrode of the triode Q1 is connected with the first resistor R1 and then connected with the weak signal input end; a resistor II R2 is connected in parallel between the base electrode and the emitter electrode of the triode Q1, and the emitter electrode of the triode Q1 is grounded; pin 3 of the optical coupler OP1 is grounded; pin 4 of the optocoupler OP1 is connected to the signal output terminal and the resistor four R4, respectively, and the other end of the resistor four R4 is connected to the power supply terminal SVCC33, wherein the signal output terminal is connected to the input terminal of the basic detection circuit a.

The basic detection circuit A consists of a TTL chip U1, capacitors from one to four C1-C4 and resistors from eleven to fourteen R11-R14; a capacitor I C1, a capacitor II C2, a capacitor III C3 and a capacitor IV C4 are respectively connected in parallel between each input end of the TTL chip U1 and a grounding end; each output end of the TTL chip U1 is respectively connected with the resistor eleven R11, the resistor twelve R12, the resistor thirteen R13 and the resistor fourteen R14 in series and then output; the conduction rate of the optical coupler OP1 is kept matched with the frequency of the input signal; the TTL chip U1 is a 74HC14D singlechip.

The working principle of the specific embodiment is as follows: the triode drive circuit who adds in the circuit drives the opto-coupler, inserts the TTL chip of signal at the output of opto-coupler, has both satisfied the driving capability of weak signal like this and has increased the security and the stability of circuit again, but need notice that the frequency of input signal is subject to the conduction rate of opto-coupler, just need change into high-speed opto-coupler if the frequency is high.

It is obvious to a person skilled in the art that the invention is not restricted to details of the above-described exemplary embodiments, but that it can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.

Claims

1. A weak signal input detection circuit, characterized by: the circuit comprises an optical coupler (OP1), a resistor I to a resistor IV (R1-R4), a triode (Q1) and a basic detection circuit (A); the No. 1 pin of the optical coupler (OP1) is connected with a resistor III (R3) and then is connected with a power supply electrode (SVCC 1); the No. 2 pin of the optical coupler (OP1) is connected with the collector of the triode (Q1); the base electrode of the triode (Q1) is connected with the first resistor (R1) and then is connected with the weak signal input end; a second resistor (R2) is connected in parallel between the base electrode and the emitter electrode of the triode (Q1), and the emitter electrode of the triode (Q1) is grounded; the No. 3 pin of the optical coupler (OP1) is grounded; the No. 4 pin of the optical coupler (OP1) is respectively connected with the signal output end and a resistor four (R4), the other end of the resistor four (R4) is connected with the power supply end (SVCC33), and the signal output end is connected with the input end of the basic detection circuit (A).

2. A weak signal input detection circuit according to claim 1, characterized in that: the basic detection circuit A consists of a TTL chip (U1), a capacitor one to a capacitor four (C1-C4) and a resistor eleven to fourteen (R11-R14); a first capacitor (C1), a second capacitor (C2), a third capacitor (C3) and a fourth capacitor (C4) are respectively connected in parallel between each input end of the TTL chip (U1) and a ground end; and each output end of the TTL chip (U1) is respectively connected with the resistor eleven (R11), the resistor twelve (R12), the resistor thirteen (R13) and the resistor fourteen (R14) in series and then output.

3. A weak signal input detection circuit according to claim 1, characterized in that: the conduction rate of the optical coupler (OP1) is kept matched with the frequency of the input signal.

4. A weak signal input detection circuit according to claim 2, characterized in that: the TTL chip (U1) is a 74HC14D singlechip.