A general purpose EMI / RFI shielding spray for use on plastic electronics enclosures. Consists of a tough, durable acrylic base pigmented with a high purity nickel, silver coated copper or silver flakes.
Common-Mode Choke
Narrowband interference arises from intentional transmissions - radio and TV stations, pager transmitters, cell phones, etc.
Broadband interference comes from incidental radio frequency emitters - electric power transmission lines, electric motors, thermostats, etc.
High-speed switching devices - TV, computer, and other digital equipment, etc.
Putting common-mode chokes on your feedline, power, and other cables will substantially reduce your received noise level. Simple RF choke works as a balun by preventing signals passing along the outside of the braid.
Balun can be considered as simple forms of transmission line transformers. A transmission line transformers use small ferrite cores in toroidal or "binocular" shapes. Something as simple as 10 turns of coaxial cable coiled up on a diameter about the size of a dinner plate makes an extremely effective choke balun for frequencies from about 10 MHz to beyond 30 MHz.
Toroidal-core
Binocular-core
Ferrite bead is used as a passive low-pass filter. It filters out the high frequency noise in the circuit by dissipating it as heat. The material used to construct the bead becomes highly resistive at the design frequency range and the induced current inside the bead is dissipated as heat instead of inducing an opposing current back in the signal cable (magnetic field within the bead is unable to establish properly at that specific frequency range).
Clamp-on cores can be attached without wrapping the wire at all. Although the wire is not coiled around the core, the introduction of the ferrite core around the wire increases the self-inductance of the wire thus still has the effect of absorbing energy from the noise traveling in the wire.
PCB Design
Extra (for fuses)
See the Discussion on Home Power Line Noise at below.
