Inductors, Ferrite Beads & Common-Mode Chokes
Inductors, ferrite beads and common-mode chokes
This mixed collection contains wound power inductors, small SMD and leaded inductors, audio crossover coils, ferrite beads, common-mode chokes, bare magnetic cores and bobbins. It also includes a few complete modules, sensors, testers and resistors whose supplier titles mention “inductor.” These are not one interchangeable part class: start with the circuit's actual electrical and mechanical requirement and inspect the selected product variant.
Choose the correct component family
- Power inductors: Shielded and unshielded SMD styles, radial drum-core parts and toroids are listed with values in nH, µH or mH. For a DC-DC converter or filter, compare inductance at operating current, saturation current, RMS/temperature-rise current, DC resistance (DCR), core loss at switching frequency, tolerance, footprint and thermal conditions. A 10 µH option or a similar case size alone is not enough.
- Audio crossover coils: Air-core and magnetic-core coils and wound audio inductors require the crossover's specified mH value, DCR, wire size, current and physical orientation. Core material and DCR can change circuit behavior; “OFC” or “HiFi” does not establish acoustic performance. Do not mistake a coil's µH/mH value for ohms.
- Ferrite beads and bare cores: Chip beads are often selected by impedance in Ω at a stated test frequency, DC resistance and rated current, not by a headline resistance value. A “100R” ferrite option is not a 100 Ω resistor or a 100 µH inductor. Bare bead sleeves, toroidal cores and transformer bobbins are raw materials, not fully wound inductors; check core material, geometry and winding design.
- Common-mode and differential-mode filtering: Two- or multi-winding common-mode chokes for USB/signal lines and higher-current power lines have winding configuration, common-mode impedance versus frequency, DCR, rated current, insulation and safety requirements. They are not mechanically or functionally equivalent to a single-winding power inductor or a ferrite chip bead. A 90 Ω impedance label does not specify an inductance or guarantee USB, automotive or mains compliance.
- Complete assemblies and unrelated results: Listings for inductive wireless LED modules, DC-DC boards, LCR testers, printer encoders, game-console sensor bars and cement resistors remain in this collection but are not bare inductors. Compare their own product contents and specifications separately.
Selection workflow
- Identify whether the circuit needs energy storage, tuned/RF inductance, speaker crossover inductance, high-frequency noise impedance, common-mode rejection or only a magnetic core.
- Read the exact selected variant's unit and specification. Some supplier options labeled “Resistance” contain µH/mH inductance, while “Value of Resistance” may contain nH/µH; option labels are not proof of electrical resistance. Confirm measurement conditions, tolerance and frequency.
- For wound inductors, verify saturation and temperature-rise current independently of the displayed nominal inductance; check DCR, frequency-dependent losses, package dimensions, pin arrangement and PCB or chassis mounting. For common-mode chokes, compare winding count, isolation and relevant safety documentation at the intended voltage.
- For beads, compare the impedance-versus-frequency curve, bias-dependent behavior and rated current. An Ω impedance at a test frequency is not the same as DC resistance or a substitute for a known series resistor.
Buying checklist and FAQ
Record the schematic role, original part number, nH/µH/mH or impedance at its test frequency, tolerance, current and saturation requirements, DCR, operating frequency, footprint or lead pitch, core material, ambient temperature and selected pack count.
Are 10 µH inductors with the same footprint equivalent? No. Check saturation current, DCR, losses, tolerance and temperature rise for the application.
Does “100R” on a ferrite bead mean a 100 Ω resistor? No. A bead's impedance is frequency-dependent; verify the exact test conditions and DC resistance.
Can a common-mode choke replace a power inductor? No. Winding arrangement and filtering function differ; use the circuit's specified part type.
