摘 要 本系统以单片机为核心，单片机 AT89C51 具有功能强，体积小，功耗低，价格便宜，工作可靠，使用方便等特点。所以在本设计中采纳单片机 AT89C51 作为控制器来控制电路。辅以键盘，显示电路，利用热敏电阻对热水器出口温度进行检测，将温度转换成频率，并将其反馈到单片机，用单片机测出频率大小，从而间接测出温度值，温度/温度转换电路简单可靠，成本低廉。对于加热功率的控制，本文采纳了双向可控硅控制，单片机通过光耦给可控硅触发信号，控制可控硅的导通角，从而控制电热丝的有效加热功率。为了在关机和超温保护的状态下能可靠地关断加热电源，电路中加入了继电器来控制加热电源。其中串联在继电器线圈回路的熔丝为105℃时，保险丝会熔断，防止加热管干烧。与电热丝并联的 LED 发光管用来指示电热丝的工作状态。关键词：单片机 温度 双向可控硅 继电器。AbstractThis system based on singlechip with powerful function, SCM AT89C51, small volume, low power consumption, low price and reliable, easy to use. So in this design USES AT89C51 microcontroller as the controller to control circuit. With the keyboard,, using thermistors display circuit of water heater, will exit temperature, temperature and frequency convert their feedback to measure frequency with single-chip microcontroller, size and indirect measure temperature, temperature/temperature circuit is simple, reliable, low cost. For heating power control, this paper adopts a two-way thyristor controlled by single chip computer controlled light-coupler to control thyristor trigger signal, the conduction angles, and the effective control of heating heating power. In order to protect the shutdown and overtemperature condition can be reliably shut off the power circuit joined to control the heating power. Relays, One of the series in relays for welding wire coil loop 105 ° c, heat fuses will fuse, prevent heat pipe up. In parallel with the electric wire LED to work instructions resistanse wire work...
