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.