A fire telephone extension voice return circuit and its implementation method

Abstract

The invention discloses a fire-fighting telephone extension voice return circuit. The voice return circuit comprises a microphone MICI, a voltage-current converter D3A, a voltage-dividing capacitor C12, a triode V6, a follower D3B and an NMOS transistor Q1. The invention also provides an implementation method of the return circuit. The implementation method comprises the following steps: (S1) themicrophone MIC1 converting an acquired audio signal into a variable voltage signal and reaching the positive input end of the voltage-current converter D3A; (S2) after the voltage signal is convertedinto a current signal through a voltage-current converter D3A, loading the current signal to a bus through a triode V6, and the bus allowing an extension set to return the current signal in a coding gap; (S3) after the current signal passes through a triode V6, outputting two paths of signals from an emitting electrode, and respectively connecting the two paths of signals with a negative input endof a voltage-current converter D3A and a positive input end of a follower D3B; and (S4) when the single-chip microcomputer gives a high level to the resistor R22, turning on the NMOS tube Q1, and when the single-chip microcomputer gives a low level to the resistor R22, turning off the NMOS tube Q1. According to the scheme, the purposes of high anti-interference capability, high noise suppressioncapability and high load capability are achieved.

Description

technical field [0001] The invention belongs to the technical field of firefighting, and in particular relates to a voice return circuit of a firefighting telephone extension and a realization method. Background technique [0002] As a special equipment for fire communication, the fire phone can provide people with convenient and fast means of communication when a fire occurs. It is an indispensable communication device in the fire control and alarm system. The fire telephone is divided into four-wire system and bus system. At present, the fire telephone of the bus system is commonly used in the industry, that is, the fire telephone extension is connected to the fire telephone host through two wires, and the bus realizes the connection of digital signals and audio signals at the same time. transmission. Since the audio signal is coupled to the bus in an analog way, the bus has poor anti-interference ability, weak load capacity, limited number of extensions and jacks, and sh...

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to provide a fire telephone extension voice return circuit and its implementation method, which mainly solves the problem that the existing voice conversion circuit existing in the prior art is complicated and costly

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