5pcs Iron Powder Toroid Cores T37 T50 Carbonyl Ferrite Rings

5pcs Carbonyl Iron Powder Toroid Cores — T37-6 / T37-2 / T50-2 / T30-2

Upgrade your RF, audio, or power electronics projects with these precision-wound carbonyl iron powder toroid cores. Sold in a convenient 5-piece set, these red-coated ferrite toroid rings deliver stable, high-performance magnetic characteristics across a wide frequency range — making them an ideal choice for inductors, filters, chokes, and transformers in amateur radio, DIY electronics, and professional circuit design.

Specifications

• Models Available: T37-6 / T37-2 / T50-2 / T30-2
• Material: Carbonyl iron powder
• Color Coating: Red
• Outer Diameter: 7.8 mm
• Inner Diameter: 3.84 mm
• Height: 3.25 mm
• Quantity: 5 cores per pack

Made in Mainland China.

Key Features

• High Saturation Magnetic Flux Density: Handles large currents without saturating, keeping your circuits stable under demanding load conditions.
• Excellent Frequency Characteristics: Effective permeability remains consistent across a broad frequency range, ensuring reliable signal integrity for RF and audio applications.
• High-Temperature Stability: Engineered to maintain performance characteristics at elevated temperatures, suitable for demanding environments.
• Low Electromagnetic Radiation (Toroidal Design): The annular (ring) structure inherently contains magnetic flux, minimizing electromagnetic interference and reducing the need for additional shielding — saving both materials and cost.
• Durable Coating: Color-coded red coating protects the core and helps identify the material mix at a glance.

Common Applications

• RF inductors and low-pass filters for amateur (ham) radio
• Switching power supply chokes and transformers
• Audio crossover networks and signal filters
• EMI suppression and noise filtering in electronic circuits
• DIY electronics, prototyping, and hobbyist projects

What's in the Box

• 5 × Carbonyl Iron Powder Toroid Cores (your selected model)

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Learn More About Magnetic Core Materials

For technical background on magnetic materials and their use in electronics, visit the NIST Magnetic Properties of Materials resource.

Learn more: Inductor

Frequently Asked Questions

Q: What is the difference between the T37-6 and T37-2 iron powder toroid cores?

A: The T37-6 and T37-2 have the same physical size (T37 designation) but differ in material mix. The "-6" mix (yellow/clear) is optimized for higher frequencies (up to ~40 MHz), while the "-2" mix (red) offers a higher permeability and is better suited for lower frequency applications such as AM broadcast and medium-wave inductors. The red-coated cores in this listing correspond to the "-2" mix, known for stable performance and higher inductance per turn.

Q: Are these toroid cores suitable for amateur radio (ham radio) projects?

A: Yes — T37 and T50 series carbonyl iron powder toroid cores are among the most popular choices for ham radio builders. They are widely used in constructing RF chokes, bandpass filters, low-pass filters for antenna tuners, and impedance-matching transformers, making them a staple in QRP and homebrew radio kits.

Q: How do I wind an inductor on a toroid core?

A: To wind an inductor, pass your enameled copper wire through the center hole of the toroid core the required number of times as specified by your circuit's design formula. The number of turns, combined with the core's AL value (inductance per turn²), determines the final inductance. Secure the winding with a small dab of adhesive or cable tie if needed. Always consult your project's datasheet or design guide for the precise turn count.

Q: Can these cores be used in switching power supply designs?

A: Yes. Carbonyl iron powder cores with high saturation flux density are well-suited for switching power supply inductors and chokes, especially where DC bias performance is important. Verify the specific AL value and frequency range for your chosen core model against your power supply's switching frequency before finalizing the design.