Idling current
Idling current refers to the small amount of current trickling through a circuit (or more commonly through transistors) such as an amplifier when the system is on, but doing no useful work. Analog electronic circuits sometimes need to be designed while keeping the idling currents in mind, as these currents may be used to run other components in the circuit, or, more commonly, will result in undesired noise in the output.
Many electrical utilities including computer and television peripherals, (printers, scanners, DVD players, receivers, etc.), continue to use energy, even after they are turned them off. This energy ‘leak’ occur because many electronic devices can't be fully turned off without pulling the wall plug. “While the knob or button may be turned off, in reality, the device may be in any of several standby modes, somewhere between fully off and fully on, wired so that its prongs draw electric current from the wall outlet 24/7” (Woods, 2005). The exact waste from standby power is unclear due to the lack of studies conducted; however, Alan Meier, an energy analyst who helped raise awareness about the problem while at Lawrence Berkeley National Laboratory in California, estimates that residential consumers in the United States spend more than $5 billion annually on standby power -- about 5 percent of all electricity consumed in the country (Woods, 2005).
While some standby power is necessary and useful, it has exploded since 1968 on the consumer electronics scene with the introduction of the “instant-on” televisions. Earlier TVs took one to two minutes for picture and sound to appear as the set "warmed up." Standby power allows for instant-on picture and sound and is also necessary in order to keep TVs, VCRs, DVD players and other devices such as security alarms on alert and ready to receive signals from remote control units. Standby power also allows refrigerators to monitor temperature and decide when to turn on, keeps batteries in cell phones and camcorders fully charged, lights up the time display on microwave ovens, and enables toasters to toast faster. Most standby power, however, is a waste, consuming energy for no good reason, according to Meier (Woods, 2005).
Consumer concerns about standby power are leading to development of devices that make it more convenient to pull the plug on products that typically remain "on." Such products include Beamingsun's USB Ecostrip which allows the user to effectively control when peripheral devices power off by using patented USB technology. Also, OneClickPower, a British firm, has been selling a "smart" surge protector with outlets for a computer, monitor, printer, scanner and other devices. Its circuitry senses when the devices go into a standby mode and automatically disconnects them (£29.95). Another similar product is the Smart Strip which monitors power consumption and can sense the difference between when computers and other devices are on or off. Upon figuring this out, it shuts off the power, eliminating the idling current drawn from them (US $32-$35). A third option is the Wattstopper which has six outlets controlled by occupancy and two outlets which are uncontrolled (read: normal), and use a motion detector of sorts to monitor and manage energy use. Devices plugged into the controlled outlets are turned on and off based on occupancy, or the fact that they're currently using energy. The "Personal Sensor" connects to the power strip, and automatically turns power to all connected devices on when the accessories and peripherals are in use. These devices will turn off after they go idle and the user-defined time delay elapses (anywhere from 30 seconds to 30 minutes) (US $90). (Dunn, 2005)
External links
Dunn, Collin, 2005 “’Smart’ Power strips: Helping to Stop Idle Current Now!”