Custom Inductors | Air Coils, EMI Filters & RF Inductors

Expert Design & Manufacturing Since 1947

Custom Inductors for Mission-Critical Applications

ECI specializes in the design and manufacture of high-performance inductors for aerospace, defense, medical, and industrial applications. Our comprehensive inductor solutions include air coils, common mode EMI filters, current sensors, and RF tuned inductors, all manufactured to the highest quality standards.

Why Choose ECI

AS9100/ISO9001 certified manufacturing with ITAR registration
Automated air coil winding technology for high-precision production
Custom electromagnetic solutions for harsh environments
Established in 1947 with decades of magnetic component expertise
In-house environmental testing capabilities

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Our Inductor Solutions

Air Coil Solutions

ECI is proud to offer automated air coil winding solutions, enabling high-precision, repeatable air coil solutions for high volume production applications. Our automated systems and lab-based process controls enable tightly wound, coplanar coils with consistent lead alignment and high electrical performance.

Key Capabilities:

Wire size range: #24 – #15 AWG
Coil I.D. range: 0.040" – 0.315"
Clockwise and counter-clockwise winding
Close-wound or space-wound options
Overall coil length up to 0.905"

Process Highlights:

Exceptional precision and coplanarity — lead lengths sit perfectly flush. Automated trim, tinning, winding and cutting to exact specifications.

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Common Mode / EMI Filter Inductors

Common Mode Inductors (also called Current Compensation Chokes) operate where current flows on both "line" and "neutral" to "ground". By attenuating high-frequency common mode noise currents, conducted emissions (EMI) are minimized, making these components essential for meeting EMC compliance requirements.

Key Features:

Minimum 3mm creepage & clearance between windings
Compatible with safety agency requirements & standards
Single layer toroidal geometries maximize common mode impedance
Wide frequency range optimization (maximized inductance & minimized capacitance)
High impedance to common mode noise while allowing differential current flow

Technical Details:

Parasitic capacitance between circuit components and chassis "ground" induces common mode noise resulting in conducted EMI. While operating in "common mode", the flux generated by the current flow is additive as the current travels "commonly" through both lines and returns through the reference "ground". This allows the differential current to flow unimpeded while suppressing the conducted EMI.

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Current Sensors

AC Current Sensors (or CTs) are typically used in feedback control circuits, overload sensing, and measuring load changes. These precision components provide accurate current measurement through magnetic coupling, enabling real-time monitoring and control in critical applications.

Key Applications:

Feedback control circuits
Overload sensing and protection
Load change measurement
Power monitoring systems
Circuit protection applications

Operating Principle:

A current sensor functions by inducing a proportional current, via a magnetic field, into a secondary winding — typically by coupling the conductor to be measured with a winding wound around a toroidal core. The wound coil is terminated with a burden resistor, and the voltage is measured across that resistor. Sensitivity is controlled by the terminating resistance and the number of secondary turns.

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RF & Tuned Inductors

ECI offers precision RF inductors for demanding communications and signal processing applications. Our RFA1-XXX series delivers exceptional performance with tight tolerances and excellent stability across a wide range of operating conditions.

Key Specifications:

RFA1-XXX series with ±1% inductance tolerance
High "Q" coils for minimal losses
Excellent self-resonant frequency characteristics
Operating temperature range from -55°C
Manufactured to MIL-C-15305 standards
Available in tape & reel packaging

Configuration Options:

Wire-wound RF inductor configurations include radial and axial leaded, toroidal, air-core and SMT. Wound devices can also be constructed using semi-rigid or flexible coaxial cable. Other devices include tuned notch filters and directional couplers.

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How Inductors Work

Inductors temporarily store energy within their magnetic fields, resulting in a current flow that "lags" the voltage across the inductor due to "back emf" opposing that current flow. An increasing current flowing through a coil generates a magnetic field.

As that magnetic field is building, the flow of current is inhibited until the current reaches steady state when there is no longer resistance to the current flow. As the current flow decreases, the magnetic field decreases, releasing the stored energy back to the circuit, temporarily maintaining current flow. This property can be used to soften current surges or spikes within a circuit. An inductor that is used to pass direct current (DC) while blocking high frequency alternating currents is called a Choke, due to its increasing impedance at rising frequencies, thus suppressing high frequency "noise".

Custom Inductor Engineering

The Complete Solution

ECI’s engineering team works to design the "complete solution" with fully integrated electrical parameters and mechanical packaging to suit unique needs. The team approaches each design with a focus on long-term manufacturability while meeting any environmental and safety agency requirements.

Built for Harsh Environments

ECI is recognized for the ability to mitigate effects of harsh environments utilizing unique packaging and treatment methods while still preserving optimal electrical performance, and is considered an expert in designing for mission-critical applications.

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Toroidal Winding Technology

The ECI team designed and patented an automated "Orbital" and "Shuttleless" toroidal winder to better service our customer base. This proprietary technology enables superior consistency and performance in toroidal inductor manufacturing.

To contain the magnetic field and reduce radiated EMI, a toroidal geometry is a good choice. If additional shielding is desired, a ferrite sleeve or Mu-metal shielding can be incorporated.

Our Manufacturing Expertise

Inductor Applications

ECI inductors serve mission-critical applications across multiple industries. Common applications include power converters for energy storage, EMI noise filtering, and tuned circuits when combined with capacitors and resistors.

Aerospace & Defense

Avionics, power systems and ruggedized magnetics for airborne and military platforms

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Medical

Imaging systems, patient monitors and surgical equipment

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Security

Surveillance and protection systems requiring high reliability

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Industrial

Power management, motor control and automated manufacturing systems

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Commercial

Power conversion, filtering and tuned circuits for commercial electronics

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Quality Assurance & Compliance

ECI maintains the highest quality standards in the industry.

Certifications & Registrations

AS9100 / ISO9001 certified quality management system
ITAR registered for defense applications
MIL-C-15305 compliance for RF inductors

Testing & Standards

In-house environmental testing capabilities
Safety agency requirements & standards compliance

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Frequently Asked Questions

What types of inductors does ECI manufacture?

ECI manufactures four main categories of inductors: Air Coil Solutions with automated winding capabilities, Common Mode / EMI Filter Inductors for noise suppression, Current Sensors (CTs) for feedback control and load sensing, and RF & Tuned Inductors including the RFA1-XXX series with ±1% tolerance.

What is your automated air coil winding capability?

Our automated air coil winding solutions handle wire sizes from #24 to #15 AWG, with a coil I.D. range from 0.040" to 0.315", and overall coil length up to 0.905". We offer both clockwise and counter-clockwise winding, close-wound or space-wound options, with exceptional precision and coplanarity.

How do common mode inductors suppress EMI?

Common mode inductors allow differential current to flow unimpeded while suppressing conducted EMI by presenting high impedance to common mode noise currents. They are typically constructed with minimum 3mm creepage & clearance between windings, and single layer toroidal geometries maximize common mode impedance over the widest frequency range.

What is the RFA1-XXX series?

The RFA1-XXX series is ECI’s family of axial leaded RF inductors, precision tuned to ±1% inductance tolerance. These high "Q" coils offer very high self-resonant frequencies and excellent temperature stability with an operating temperature range from -55°C. They are manufactured to MIL-C-15305 and available in tape & reel.

Can ECI design custom inductors for harsh environments?

Yes. ECI is recognized for the ability to mitigate effects of harsh environments utilizing unique packaging and treatment methods while preserving optimal electrical performance. We are considered experts when designing for mission-critical applications in aerospace, defense, and other demanding industries.

What quality certifications does ECI maintain?

ECI maintains AS9100 / ISO9001 certification and ITAR registration. We have in-house environmental testing capabilities and manufacture RF inductors to MIL-C-15305 standards. All products meet applicable safety agency requirements and standards.

Partner With ECI

With over 75 years of experience in magnetic component design and manufacturing, ECI is your trusted partner for custom inductor solutions. Our automated winding technology, comprehensive testing capabilities, and commitment to quality ensure reliable performance in the most demanding applications.

Contact our engineering team to discuss your inductor requirements.

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Custom Inductor Solutions