1. Operational Amplifiers
Lab 7 Overview
Operational Amplifiers

2. What are Op-amps for? Op-amps have many, many uses
amplifiers in general are used to change the amplitude of voltage signals
A typical application of op-amps is in audio systems
Video from Jonathan Hull’s Lab 7 Step 7 Audio Amp Extra Credit Demo Sp16
Our hardware has changed a bit since this version, and the speaker is much more robust!
Video from Jonathan’s Lab 7 Step 8 Audio Mixer Extra Credit Demo

3. How to wire a real op-amp circuit?
Inverting Amplifier Test Circuit

4. Amplifiers make more sense with AC signals…
EveryCircuit Demo of Inverting Op-Amp
Notice the way the output voltage is flipped
Notice the effects of saturation (output sinewave is flattened at high amplitude)
…but we will start the lab with DC signals to really understand how they work
Constructing dual +12V and -12V supply
Using a potentiometer to get a variable voltage source
Measuring voltage at the different pins of the op-amp
Calculating gain, plotting Vout vs Vin, observing saturation

5. How our circuit looks in Circuits.IO
Circuits.io simulation of Inverting Op-Amp

6. The Inverting Op-Amp Transfer function
We will measure and plot
Gain is the slope of the line
Saturation at limits

7. Saturation
When the output voltage doesn’t leave enough room for transistors in op-amp to work properly
An intentional effect for heavy metal guitar amps

8. Other stuff Repeat with a Non-inverting Op-Amp
Extra Credit Audio Amplifier and Audio Mixer circuits