Make: More Electronics

Chapter 11. Experiment 11: The Need for Negativity

Now that you’ve seen that an op-amp can amplify, I want to address two questions:

1. How can we determine how much it is amplifying?
2. How can the output become a more accurate copy of the input, so that if we listen to it through a loudspeaker, the noise won’t sound scratchy?

In this experiment I’m going to guide you through the process of answering the first question. I’ll deal with the second question in Experiment 12.

Messing with Measurement

In an ideal world, measuring the amplifying power of an op-amp would be a no-brainer. You’d have a signal generator to create a steady sine-wave input. You’d also have an oscilloscope, which would display the sine wave on its screen. You would check its amplitude ...