Design Of Anti-theft Voice Alarm With Low Standby Power Consumption And High Efficiency For The Bank

The bank security alarm system,as an important part of bank security system,is composed of the alarm signal detection part,control part,and the alarm signal transmit part.This dissertation mainly studies the transmitting and controlling parts of the voice alarm signal of the alarm,after the analysis of a variety of the host principle and structure of security alarm system that are used in banks and commercial places,as well as the circuit system design,and the dissertation finds out the deficiency,puts forward a new circuit system design method and designs a kind of anti-theft voice alarm with low standby power consumption and high efficiency.Firstly,in order to improve the conversion efficiency of host power supply,reduce the volume of power supply,bring down the power consumption of the machine,this dissertation designs standby and alarm two modes of working power supply respectively.When in standby mode,it uses the low power switching power supply which is based on TNY274 design,and works in half wave way,minimizes the standby power consumption;And when in alarm mode,it uses the constant current/constant voltage main power supply which is based on TOP223Y design,provides a constant output voltage to load,at the same time,it also can provides a constant output current to rechargeable battery,makes the main power and standby power can no dropout voltage while in switching.Not only ensure the stability of the power supply voltage,but also optimizes the circuit design.Secondly,in the voice alarm signal power amplifier section,is adopted to the current mode PWM control chip KA3525 to design the adjustable output voltage of tracking mode dynamic DC power Supply,and is adopted to two complementary transistors and op-amp TL084 to design the special linear power amplifier.Using a combination can make the collector voltage of power amplifier track changes on the output voltage,thus greatly reducing the loss,improving efficiency and enhancing rapid protection feature when in the short circuit.Finally,in addition,this dissertation designs the self-check function of the system,including voice chip,power amplifier,the state of the rechargeable battery,etc.In order to prevent the speaker from making a lot of sound when detecting the DC working status and the AC working state of the power amplifier,using more than 10KHz voice signal to test.This dissertation has made the prototype of anti-theft voice alarm,also has conducted a comprehensive test.Actual test data indicates that the whole standby power consumption of the low standby power and high efficient anti-theft voice alarm is below 0.1 W,and the average efficiency of the tracking mode dynamic DC power supply based on the KA3525 has reached 92%,the average efficiency of the working voltage variable linear power driver stage has reached 91%,the average efficiency of power amplifier driver stage has reached upwards of 84%,as well as the machine efficiency reached 72%,to compared with the ordinary anti-theft voice alarm,it greatly reduces the power consumption and the volume,and improves the efficiency and the stability of the product,saving the cost.