الفهرس 
Gain of feedback amplifierOnly 14 pages are availabe for public view
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Abstract
a temperature controller circuit was designed which can serve in solid state laboratories to keep any system at a desired temperature with accuracy of (kloC this depends on the accuracy of the (AID & D/A) card). Which idea of the controller is based on supplying part of the rectified wave to the heater. This part depends on the required temperature. In our design, initially the full voltage is -supplied to the heater, and with increasing the temperature this voltage will decrease gradually to a certain value until the desired temperature is reached. This part of ac voltage is sufficient to obtain this degree, and a steady state is reached. After an hour from starting, the voltage value charges to new value to gave another temperature. This means that the power is adjustable according to the desired temperature . Any the temperature is adjusted to an accuracy +loC. The voltage adjusting the required temperature and its variation are adjusted by the computer through an (AID & D/A) card. Also the computer records the temperature and the current passing through the sample from which the sample resistance is measured.