模电设计 温度计英文.docx

1、模电设计 温度计英文Temperature Measurement, Amplification, Display and Alarm SystemLi Lan xin211208211.Tasks and requirementsRoom temperature is measured by the platinum thermistor, and the alarm sounds when the temperature is higher than the reference voltage.1. The measurement region is 0100, the output vo

2、ltage is 01V, the measurement error acceptable is in 1.2. Display the temperature with the digital voltmeter which is Double integral type. 3. The circuit detects the over temperature upper or lower than the normal region 0100, and produces alarm voice, the error should be in the region of 1.4. The

3、alarm should be displayed by both the light and the voice.2. Design principleThe circuit used to platinum thermal resistance, through the platinum resistance heat at different temperature different of this principle, the temperature signal can be converted to voltage signal, through to the voltage o

4、f series of processing, will eventually voltage variation through digital tube display of digital, so as to realize the measurement of the temperature .On the basis of the basic functions, which can realize the function of the alarm sound, etc .Is due to the digital display function of digital signa

5、ls can be realized, and the collection of temperature is an analog, so must conduct a AD conversion .This design can be divided into four modules.Design principle expressed by block diagram is as follows:3. Module design and analysis(1) Temperature -voltage conversion unitThis module is to realize t

6、he platinum thermal resistance temperature into a voltage signal, and the voltage signal through the op-amp output.Temperature is a basic physical quantities, all the process of nature is closely related with temperature .The temperature sensor is the earliest development, the most widely used type

7、of sensor .Temperature sensor has four main types: thermocouple, thermal resistance, resistance temperature detector (RTD) and the IC temperature sensor .IC temperature sensor and includes two types, that is, analog output and digital output .Platinum thermal resistance is one of the most commonly u

8、sed in thermal resistance sensors.We chose the platinum thermal resistance as the main design direction .Platinum thermal resistance of one ohm resistance are the characteristics of each change, the temperature is about 2.5 , specific mathematical formula is:200t0，Rt100=1001+At+Btt+Cttt(t-100) （1）0=

9、t Uh, the output of the op-amp A1 Uo1 = + Uom, the output of the op-amp A2 Uo2 = - Uom, conduction D1, D2 cut-off, voltage regulator tube Dz work in voltage state, output Uo = + Uz.When Ul Ui Uh, the output of the op-amp A1 Uo1 = - Uom, the output of the op-amp A2 Uo2 = - Uom, D1 deadline, as D2, ou

10、tput Uo = 0.When the Ui Ul, the output of the op-amp A1 Uo1 = - Uom, the output of the op-amp A2 Uo2 = + Uom, D2 conduction, D1 cut-off, voltage regulator tube Dz work in voltage state, output Uo =+ Uz.So when the Ui beyond the upper and lower limit, Uo = + Uz, we used the light emitting diode and a

11、 buzzer, at this time to report to alarm system.Censored by switch control.This unit we use window comparator, circuit is as follows:4.Component listTemperature display, sound and light alarm and mute circuit component listTypeName of typeParameterNumberResistance1021001450011K1010K420K24.7K2470K2Resistance box1resistance10K2Capacitynonpolarity0.1u40.05u1heteropolarity250u1Diode2Luminous diodered1green1Stabilivolt5V1AudionNPN2Integrated amplifierOP072LM1191LM3861Integrated chipMC14031MC144331MC14131CC45111Four digit LED nixie tube1Loudsapaker1Switch2