Make: More Electronics

Chapter 9. Experiment 9: From Millivolts to Volts

In the previous experiment, you determined that your electret was working. Now we can begin to make it do something useful.

Putting a Cap on It

The first step is to install a coupling capacitor, as shown in Figure 9-1. If you remember the basics, you already know that it will block DC voltage while allowing a pulse to pass through. In fact, depending on the size of the capacitor, it will be transparent to many small voltage fluctuations—such as those in an AC audio signal.

Figure 9-1. This simple test with a multimeter demonstrates that the capacitor blocks DC voltage while passing an AC audio signal. ...