So I've been getting into the world of building circuits with an Arduino controller and a breadboard. I've been working in IT for years, but I'm not super familiar with electronics at this level.
While following a tutorial for building a "knock sensor" using a piezo speaker as the sensor, it connected the piezo speaker from ground to an analog input pin on the Arduino. Then, it connected a 1M ohm resister in parallel to that. All it said was that doing so protected the Arduino from the voltage spikes caused by the knock sensor.
After asking around, I learned that this resistor was called a "burden resistor," but I can't seem to understand how adding a resistor in parallel to the element that generates the voltage would protect the Arduino board.
Can someone explain this to a newbie like me?
This is the webpage that shows the burden resistor: http://arduino.cc/en/Tutorial/Knock