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EMI Filter Overview
Electromagnetic Interference or EMI is a type of energy. EMI is often used interchangeably with RFI, Radio Frequency Interference, but technically RFI is the frequency range of the noise and EMI refers to the type of energy, electromagnetic. Electromagnetic energy produces interference, or noise, which is everywhere. It is created by lightning, rain, and even wind.

Interference is removed by the filter. EMI and RFI filters have a specified range of unwanted signals, noise, which is blocked. The filters have a circuit with a series of inductive and parallel capacitive mechanisms, also known as load-bearing and non-load bearing components, to do this.

There are a few different EMI filter phases that can exist, a single phase, a three-phase or DC. Single phase and three phase are both types of alternating current (AC) and direct current (DC) is a current that always travels in the same direction. EMI filters are rated with voltage (designed voltage), current (designed current) and insertion loss (it’s attenuation information, in decibels, dB), which is the ratio of noise without the filter to the noise with the filter installed.

In general, an EMI filter purifies a signal by diminishing the high-frequency RFI and allowing the low frequency EMI.

Dearborn Electronics offers a variety of Electromagnetic Interference filters. Selecting the correct filter for your needs is of the utmost importance. Contact us and we can help you find the right filter.

Feed Through Capacitors
Wire through or screw header types
Industrial and military grade
Low pass
Film Capacitor reliability

EMI Filters
L- Circuit
Double L-Circuit
T- Circuit
Pi-Circuit
Ceramic, Tantalum Film Capacitor designs

Features
Weight and size sensitive designs
Computer simulator software
Proto-typing available
Hermetically sealed

Performance
Broad capacitance range up to 500VDC/250VAC
Operating temperature: -55C to +125C
Wide range of currents

For more information see our EMI / RFI Subminiature Ceramic Filter Catalog (PDF).

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