2 class days Lab 8: Op Amps Lab Assignment 1. Open-Loop Test Circuit HH 8.1. Answer all questions. 2. Inverting Amplifier Source: Eyler, lab 7 (HH 8.2) Construct an inverting amplifier with an LF411 op amp, as shown in the figure below. Use R1= 10 kΩ. Vs = supply, typically ± 12V or ± 15V. Bal = balance, not needed here. Basic Inverting Amplifier with an LF411 Op Amp Choose R2 for a gain of about 100. Measure the gain, Vout/Vin, for several DC input voltage levels. You may find it easiest to construct a voltage divider with a miniature trimmer potentiometer to provide the input, since many power supplies produce voltages that are inconveniently large for this purpose. Now change R2 to set the gain to about 1, then to about 10. Does the output behave as expected? At what input and output voltages does the op amp “saturate” to a level that does not increase further? What determines the input impedance of this circuit? Confirm your prediction either by adding 1K in series with the input, or by measuring the input current directly, using a digital multimeter. Apply a SMALL sine wave to the input and determine the frequency at which the output amplitude drops by a factor of 2 relative to its predicted value. What is the approximate phase shift at this 3-dB frequency? Be sure to measure both the input and output voltages, since the signal generator may not produce a constant amplitude as its frequency is adjusted. Is the phase shift similar to that expected of a simple “single-pole” RC low-pass filter? 3. Non-inverting Amplifier HH 8.3. Answer all questions. Don’t forget about the input impedance of your scope! Do not try to measure the circuit’s input impedance. Compare your measured gain to expected. 4. I to V converter HH 8.6. Answer all questions. 5. Push-Pull Buffer HH 8.8. Answer all questions. Ignore the parts that involve a breadboard speaker. Do not answer the questions under “Listen to this improved ..”. What happens to the shape of the output as the frequency increases from 100 Hz to 500 Hz?