frequency range must be used. Optoisolators can perform the same task for digital lines but introduce signal delay. In circuits producing high-frequency noise such as computer components, ferrite bead chokes are placed around cables just before the termination to the next appliance (e.g., the computer). These present a high impedance only at high frequency, so they will effectively stop radio frequency and digital noise, but will have little effect on 50/60 Hz noise. Reinforce the shield of the signal cable connecting C1 and C2 by connecting a thick copper conductor in parallel to the shield. This reduces the resistance of the shield and thus the amplitude of the unwanted signal. A technique used in recording studios is to interconnect all the metal chassis with heavy conductors like copper strips, then connect to the building ground wire system at one point; this is referred to as star grounding or single-point grounding. However, in home systems, multiple components are usually grounded through their 3-wire power cords, resulting in multipoint grounds. Battery-powering one or more of the circuits can avoid a ground loop, because the entire device may be disconnected from mains power. A hazardous technique sometimes used by amateurs is to break the third wire ground conductor P in one of the component's power cords, by removing the ground pin on the plug, or using a cheater plug. This creates an electric shock hazard by leaving one of the components ungrounded. Balanced lines A more comprehensive solution is to use equipment that employs differential signaling. Ground noise can only get into the signal path in single-ended signaling, in which the ground or shield conductor serves as one side of the signal path. When the signal is sent as a differential signal along a pair of wires, neither of which are connected to ground, any noise from the ground system induced in the signal lines is a common-mode signal, identical in both wires. Since the line receiver at the destination end only responds to differential signals, a difference in voltage between the two lines, the common-mode noise is canceled out. Thus these systems are very immune to electrical noise, including ground noise. Professional and scientific equipment often uses differential signaling with balanced lines. In low frequency audio and instrumentation systems If, for example, a domestic HiFi system has a grounded turntable and a grounded preamplifier connected by a thin screened cable (or cables,