Custom Transformers & Inductors - Your Supply Chain Partner Since 1934
Johnson Electric Coil Company offers a comprehensive suite of services designed to simplify the development and delivery of high-performance electromagnetic components. Whether you are in the early design phase or looking to scale production, our team provides expertise that turns complex requirements into reliable, market-ready products.
Custom Transformer Design: Leveraging advanced CAD and simulation tools, we engineer isolation transformers and autotransformers that meet precise voltage, current, and temperature specifications. Our designs are optimized for efficiency, durability, and compactness, allowing you to reduce system weight and cost without sacrificing performance.
Inductor & Choke Development: From high-current power supplies to radio-frequency filtering, our custom inductors and chokes deliver superior magnetic performance and low loss. We tailor winding configurations, core materials, and packaging to ensure consistent inductance and minimal ripple across your operating range.
Rapid Prototyping & Z-CAD Design Services: Need a proof-of-concept quickly? Our rapid prototyping program turns design files into physical units within days, while our Z-CAD design service gives you ready-to-manufacture drawings that incorporate the latest material and process data.
Regulatory & Safety Compliance: Navigating the maze of international standards can be daunting. Our regulatory experts handle UL, CSA, CE, RoHS, REACH, China RoHS, conflict minerals, EU BPR, EU POP, low-halogen, and California Proposition65, ensuring your components meet all necessary safety and environmental requirements.
Lean Manufacturing & 5S Implementation: We apply lean manufacturing techniques and the 5S system to reduce lead times, eliminate waste, and maintain consistent quality. This approach guarantees that you receive your products on schedule, with traceability and accountability at every step.
Custom Scheduling & Logistics: From small batch orders to high-volume production runs, we customize packaging, shipping, and billing to fit your inventory management and delivery timelines. Our proactive communication keeps you informed and in control of every shipment.
Continuous Improvement & Customer Support: We view every project as a partnership, offering ongoing support throughout the product life cycle-from initial concept to field service. Our dedicated team is always ready to address questions, provide technical assistance, and help refine designs for future iterations.
About Us
Johnson Electric Coil Company, founded in 1934, has evolved into a world-class supplier of custom transformers, inductors, and chokes, catering to a diverse range of industries-from medical equipment and telecommunications to aerospace and industrial automation. Located in the heart of Antigo, Wisconsin, our facility has remained a bastion of precision engineering for nearly nine decades, blending traditional craftsmanship with cutting-edge technology. Our mission has always been simple yet powerful: to provide customers with reliable, high-performance electromagnetic components that enable them to excel in their markets.
At the core of our product portfolio are custom isolation transformers, autotransformers, and high-efficiency inductors and chokes. Every design begins with a meticulous analysis of the application's electrical, thermal, and spatial constraints. Our engineers craft solutions that deliver optimal voltage regulation, minimal loss, and compact footprints-whether you need a single-phase transformer for a lab instrument or a three-phase unit that powers a large-scale manufacturing line. With maximum output ratings up to 750kVA, we can produce everything from one-off prototypes to high-volume serial runs without compromising quality or cost.
Our manufacturing approach is rooted in lean principles and the 5S system, ensuring that each component is produced efficiently, accurately, and with zero waste. We support the entire product life cycle with Z-CAD-enabled design services, rapid Z-prototyping, and fully integrated manufacturing to custom specifications. Additionally, we guide clients through complex safety and regulatory requirements-UL, CSA, CE, RoHS, REACH, China RoHS, conflict minerals, EU BPR, EU POP, low-halogen, California Proposition65, and more-so that your products are market-ready from day one.
Customer satisfaction drives everything we do. From the first design consultation to the final shipment, we offer tailored scheduling, packaging, shipping, and billing to match your inventory and delivery needs. Our responsive support team works with safety agencies to secure approvals, and our global footprint means that even though we are made in Wisconsin and sold mainly in the U.S., our components are integrated into OEM equipment worldwide. Choose Johnson Electric Coil Company as your single, trusted partner for custom transformers and inductors, and experience the difference that precision, reliability, and exceptional service can make.
At the core of our product portfolio are custom isolation transformers, autotransformers, and high-efficiency inductors and chokes. Every design begins with a meticulous analysis of the application's electrical, thermal, and spatial constraints. Our engineers craft solutions that deliver optimal voltage regulation, minimal loss, and compact footprints-whether you need a single-phase transformer for a lab instrument or a three-phase unit that powers a large-scale manufacturing line. With maximum output ratings up to 750kVA, we can produce everything from one-off prototypes to high-volume serial runs without compromising quality or cost.
Our manufacturing approach is rooted in lean principles and the 5S system, ensuring that each component is produced efficiently, accurately, and with zero waste. We support the entire product life cycle with Z-CAD-enabled design services, rapid Z-prototyping, and fully integrated manufacturing to custom specifications. Additionally, we guide clients through complex safety and regulatory requirements-UL, CSA, CE, RoHS, REACH, China RoHS, conflict minerals, EU BPR, EU POP, low-halogen, California Proposition65, and more-so that your products are market-ready from day one.
Customer satisfaction drives everything we do. From the first design consultation to the final shipment, we offer tailored scheduling, packaging, shipping, and billing to match your inventory and delivery needs. Our responsive support team works with safety agencies to secure approvals, and our global footprint means that even though we are made in Wisconsin and sold mainly in the U.S., our components are integrated into OEM equipment worldwide. Choose Johnson Electric Coil Company as your single, trusted partner for custom transformers and inductors, and experience the difference that precision, reliability, and exceptional service can make.
Address:
821 Watson St
Antigo, Wisconsin 54409
US
Key Services in 2026
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