Summing Amplifier & Difference Amplifier
In this lab, we used an op amp to sum two input voltages.
Practice problem on solving op amp circuits before Lab: We leaned how to used node to calculate the V0, V2, and Vs.
Buffer Amplifiers, which doesn’t have much change in voltage when there is a big change in output voltage, therefore Vin = Vout.Inverting Amplifier, which produces an output with opposite sign, Vout = -Rf/Ri * Vi.
Pre-lab for Summing Amplifier : we used the Vout = - R3/R1 * (Va+Vb) to get the R3 should less than 600ohm.
This is the result table of our data, with Va varying from -4V to +5V, and Va keeps constant at +1V. We do fine on this lab.
To build the circuit, we used two 1k resistors, one 220 resistor, one OP 27, one Analog Discovery device to provide the two input voltages, and a multimeter to measure the output voltage:
Pre-lab for Difference Amplifier: We figure out that if we use four identical resistors, the out put voltage is simply Vout = Va - Vb.
This is the set up of this experiment. We build the circuit with four 10k resistors, one Op Amp 27, an Analog Discovery device to provide +/-5V and two input voltage.
This is the result table of our data, Va keeps constant at +1V. We do fine on this lab. We get a minimum % difference of 1% and a maximum of 3%,the results were very close to what we expected
Summary: In this Lab we learn more about about different types of OP Amp and their distinct utilities, and did two labs demonstrating how OP Amps can be used to combine and subtract two input signals.
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