What's Noise? Noise is unwanted sound judged to be unpleasant, loud or disruptive to hearing.There are two important characteristics of sound or noise - frequency and loudness.The higher the frequency, the more high-pitched a sound is perceived.Loudness of sound is commonly expressed in decibel (dB), the more intense the sound, the higher the db count. Long exposure at 85 dB is dangerous; at 120 dB, even short exposure can do damage. Here's how some sounds score: Sample dB count  Nearby Whispering 30 dB Refrigerator Humming 40 dB Air Conditioner 60 dB Lawn Mower 80 dB to...

DC Fans (direct current fans)The DC fans are powered with a potential of fixed value such as the voltage of a battery. Typical voltage values for DC fans are, 5V, 12V, 24V and 48V. AC Fans (alternating current fans)The AC fans are powered with a changing voltage of positive and of equal negative value. In general, this changing voltage has sinusoidal shape. Worldwide, the usual value of this sinusoidal voltage may vary in size and in frequency, such as 100V, 120V, 200V, 220V, 230V or 240V, and with frequency (cycles per second) of 50Hz or 60Hz....

Wiring inline fan with run on timer: Run on timer Instruction: Timer description:1) Run on time comes preset for 10min.2) Can adjust delay-time between 5 min to 30min.3) Arrow P Point to the delay-time.   Speed Controller Instruction: △:Please turn off the power when switching speed