In Circuits lab, we had to construct different types of operational amplifiers. The inverting and summing amplifiers produced similar output voltage to the calculated ones but were not negative. I was just wondering why they didn't reverse the sign in the experiment?

In the case of inverting and summing amplifiers, the output voltage would typically be negative based on the mathematical principles involved. However, if you observed that the output voltage was not negative as expected, there could be a few reasons for this:

1. Input signal polarity: In inverting amplifiers, the input signal connected to the non-inverting terminal of the operational amplifier should have the opposite polarity (i.e., inverted) compared to the input signal connected to the inverting terminal. If the input signals are not correctly connected or if there is a phase shift, the output voltage may not be negative.

To verify this, you can check if the input signals are correctly connected and have the desired polarity. Ensure that the polarity of the input signal connected to the non-inverting terminal is opposite to that of the input signal connected to the inverting terminal.

2. Power supply voltage: The operational amplifier requires a power supply to function properly. If the power supply voltage is reversed or not set correctly, the output voltage may not be negative. Make sure that the power supply voltage is correctly connected and within the specified range for the operational amplifier.

You can check if the power supply voltage is properly connected and set to the correct polarity. Ensure that the positive terminal of the power supply is connected to the appropriate pin of the operational amplifier.

3. Measurement error: It's also possible that there may be measurement errors in recording the output voltage. Verify that the measurement instruments, such as multimeters or oscilloscopes, are properly calibrated and connected.

To troubleshoot this, you can double-check the connections between the operational amplifier and the measuring instrument. Also, ensure that the measuring instrument is set to the correct range and mode for voltage measurement.

By carefully reviewing these points, you should be able to identify and rectify any issues causing the unexpected output voltage behavior in your experimental setup.