If you are working on a project where you want to get rid of EMI from entering an input you might want to look into using some ferrite beads, they can help you out in removing high frequency noise from your circuit. The ferrite looks like a variable resistor that has no impact on your circuit at low infrequence and starts to conduct to short out higher frequencies. It does this by converting the energy that is suppressed into heat.
“Ferrite beads prevent interference in two directions: from a device or to a device. A conductive cable acts as an antenna if the device produces radio frequency energy, this can be transmitted through the cable, which acts as an unintentional radiator. In this case the bead is required for regulatory compliance, to reduce EMI. Conversely, if there are other sources of EMI, such as household appliances, the bead prevents the cable from acting as an antenna and receiving interference from these other devices. This is particularly common on data cables and on medical equipment.”
