Posted by dapj20 on Nov 01, 2021 in Interface-Computer, Mixed-Circuits
This circuit uses a R-2R Ladder Resistor Network to convert digital data from PC Printer Port to Analog. This can be used as a Millivolt Source or Programmable Power Supply.
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This circuit uses a R-2R Ladder Resistor Network to convert digital data from PC Printer Port to Analog. This can be used as a Millivolt Source or Programmable Power Supply.
Measurement Of Temperature - When power transistors are used, they may tend to over heat. Likewise resistors may also overheat in the event of faults or short-circuits. The knowledge of their temperatures may be advantageous. In addition, measurement of temperature constitutes a basic necessity in day-to-day life.
This article will explain the way a simple transistor based current source is designed, this will give an idea on how some components can be used in a practical way to make the circuit do some function, the objective is not design but to become familiar with the basic ideas.
Design of a Constant Current Source
In the circuit the LED is used as a reference so to keep it cool a 2.2K is chosen. (20V - 1.6V) / 2.2K = 8.3mA on the high side and when voltage is 10V the current will be 3.8mA min.
Thermocouple is the most common sensor in Industrial Temperature Measurement. The Signal Conditioning involves Cold Junction Compensation and High Gain DC Amplification. The output of a Themocouple is in millivolts.
Blind Dial Proportional Temperature Controller
The OP07 is a low offset 75uV opamp, here it is used to amplify the output of a Thermocouple, the gain of this stage is high. The zeners are to protect any high voltage at input zapping the opamp.