Common Forms of Noise
Noise does not always appear in the same way. Sometimes it shows up as a sudden spike, and other times it appears as a continuous disturbance mixed into a signal.
One common type of noise is an impulse. An impulse is a very short but very large voltage spike. It often occurs when motors start, relays switch on or off, or inductive devices such as coils are energized.
Even though it lasts only a brief moment, an impulse can cause serious problems. It may reset a controller, lock up a system, or cause equipment to behave unpredictably.
Another common form of noise appears as a constant disturbance riding on top of a signal or power line. Instead of a single spike, the noise is present all the time.
When this happens on a power line, electronic equipment may become unstable. Measurements may fluctuate, displays may flicker, and sensitive circuits may not perform as expected.
Communication systems can also be affected. Noise may corrupt data and cause communication errors, leading to unexpected behavior.
Audio equipment provides another familiar example. When noise enters an audio system, it is often heard as buzzing, humming, or static.
The worst situation is when both continuous noise and voltage spikes are present at the same time. Without proper protection, reliable operation becomes very difficult.