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Adder (summing amplifier)

The purpose of this circuit is to add two voltages. (The circuit also inverts the signals, producing an output that is equal to the negative of the sum of the two input voltages).

Adjust the two sliders on the left to change the input voltages to the circuit. The two input signal currents merge and flow together through the feedback resistor. The nominal gain for input 1 is -Rf/R1 and for input 2 is -Rf/R2. You can change the gain by changing the values of any of the resistors. You can also change the differential input resistance (typically 1 to 100 Megohm) and and the open-loop gain (typically 50000 to 200000).

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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.