Electronics notes/inductors

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This is for beginners and very much by a beginner. It's meant to try to cover hobbyist needs, and as a starting point to find out which may be the relevant details for you, not for definitive information.

Some basics and reference: Volts, amps, energy, power · Ground · batteries · resistors · changing voltage · transistors · fuses · diodes · varistors · capacitors · inductors · transformers · baluns · amplifier notes · frequency generation · skin effect

And some more applied stuff:

IO: IO and wired communication · localish communication · wireless (ISM RF, GSM, RFID, more) · 802.11 (WiFi) · 802.15 (including zigbee)

Sensors: General sensor notes, voltage and current sensing · Knobs and dials · Pressure sensing · Temperature sensing · humidity sensing · Light sensing · Movement sensing · Capacitive sensing · Touch screen notes

Actuators: General actuator notes, circuit protection · Motors and servos · Solenoids

Some stuff I've messed with: Avrusb500v2 · GPS · Hilo GPRS · Bluetooth serial · JY-MCU · DMX · ESC/POS notes

Audio notes: basic audio hacks · microphones · amps and speakers · device voltage and impedance, audio and otherwise ·

Less sorted: Common terms, useful basics, soldering · Microcontroller and computer platforms · Arduino and AVR notes · ESP series notes · Electronics notes/Phase Locked Loop notes · mounts, chip carriers, packages, connectors · signal reflection · pulse modulation · electricity and humans · Unsorted stuff

See also Category:Electronics.

Inductor intro

Choke (application)

A choke is an inductor that blocks/decouples higher-frequencies.

Ferrite beads

Ferrite beads, also known as ferrite chokers, are designed to eat a certain range of frequencies, and turn it into (a negligible amount of) heat.

They work as inductors, and act as a passive low-pass filter.

One thing they address are that oscillators such as clock generators (and modern power supplies, since they're typically switch-mode) act as little radio-frequency transmitters, particularly when there is something around to act like an antenna, such as wires.

So high frequencies easily get around. While most things are fine with a little high frequency EM around, not always. So there's regulations about this.

You pass these tests by suppressing things. Ferrite beads can do this.

Note that often it's easier to suppress earlier (near the source) rather than later (on an external wire), meaning that ferrite beads are sometimes a sign of laziness.

And in some cases they're not particularly necessary for your case, but e.g. qualifying for worldwide RF emission tests made it easier to slap one onto the cable and be done with a single variant that passes worldwide.

Note that since they're inductors, mis-applied ferrite beads could cause resonance. So don't just slap on one you found somewhere because you think it will Magically Make Things Better.

See also: