公开(公告)号：US5744973A

公开(公告)日：1998-04-28

申请号：US505831

申请日：1995-07-21

申请人： Douglas D. Bird

发明人： Douglas D. Bird

IPC分类号： G01K7/24 ,  G01R27/08 ,  G01K7/00 ,  G05D23/00

CPC分类号： G01K7/245

摘要： A resistance to frequency circuit for measuring the ambient temperature on a thermostat. The temperature measuring circuit comprises a first Schmitt trigger NAND gate, a rectifier, a capacitor of which one terminal is electrically connected to ground, a first resistor, a thermistor and possibly a second resistor. The capacitor is connected with the cathode electrically connected to ground, the anode is electrically connected to the first input of a NAND gate. The output of the NAND gate is electrically connected to the anode of the rectifier. The cathode of the rectifier is electrically connected to both the thermistor and the first resistor. The second terminal of the first resistor is electrically connected to the anode of the capacitor and the first input to the NAND gate. The thermistor is electrically connected to a tri-state buffer of the microprocessor. The circuit uses the open drain output ports of a microprocessor to provide the multiplexer function of the A/D. Two precision resistors are connected to the cathode of the rectifier with their second terminals electrically connected to a second and third tri-state buffer. By selectively switching through the tri-state buffers, and measuring the resulting frequencies, errors in the system can be calculated and thereby eliminated from the measured temperature of the system.

摘要翻译： 用于测量恒温器上的环境温度的耐频率电路。 温度测量电路包括第一施密特触发器与非门，整流器，一个端子电连接到地的电容器，第一电阻器，热敏电阻器和可能的第二电阻器。 电容器与阴极电连接，与阳极电连接到NAND门的第一输入端。 NAND门的输出电连接到整流器的阳极。 整流器的阴极电连接到热敏电阻和第一电阻。 第一电阻器的第二端子电连接到电容器的阳极，并将第一输入端与NAND门电连接。 热敏电阻电连接到微处理器的三态缓冲器。 该电路使用微处理器的开漏输出端口提供A / D的多路复用器功能。 两个精密电阻器连接到整流器的阴极，其第二端子电连接到第二和第三三态缓冲器。 通过选择性地切换三态缓冲器并测量所得到的频率，可以计算系统中的误差，从而从系统的测量温度中消除。