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Integrator

Download for Macintosh or for PC.

The purpose of this circuit is to generate an output voltage Vout that changes constantly with time at a rate determined by the input voltage Vin. The greater the input voltage, the faster the output voltage changes. If the input voltage is positive, the output voltage changes in a negative direction (becomes less positive or more negative). If the input voltage is negative, the output voltage changes in a positive direction (becomes more positive or less negative). If the input voltage is zero, the output voltage stops changing and remains constant.

The practical applications of this circuit are to generate a "ramp" voltage and to measure the area under the peaks in recorded spectra or chromatograms.

Click on the run/hold switch to start and stop the integrator. Drag the slider to vary the input voltage. Click on the reset switch to reset integrator to zero.

This slider controls the input voltage. The current through the input resistor is given by Vin/R. (The inverting input of the op amp is virtual ground). The input current flows only through the feedback capacitor C. The current flowing into the feedback capacitor generates an output voltage equal to -Vin*t/RC

Note: The rate at which the output of the integrator changes in this simulation depends on the speed of your computer. The rate varies in the proper way with respect to R, C, and the input voltage, but its absolute value will not be correct on all computers.

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This page is maintained by Prof. T. C. O'Haver , Department of Chemistry and Biochemistry, The University of Maryland at College Park. Comments, suggestions and questions should be directed to Prof. O'Haver at toh@umd.edu.
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