ZXY-B2511 Permalloy Audio Isolation Transformer, 1:1, 1.0 H, 300 Hz to 4 kHz, Compact SMD

1. Product Name

ZXY-B2511, a shielded Permalloy audio isolation transformer with two independent 1:1 windings: ED8×10 Permalloy core supplied by Jiangsu Hongyun Precision Industry, wound on a Sumitomo Bakelite PM9820 bobbin, using 2UEW-H 180 °C magnet wire, wrapped with PF(8) tape, impregnated with E962 varnish, and terminated with lead-free Sn-0.3Ag-0.7Cu solder. Four SMD gull-wing pins; body 12.0 mm max × 9.3 mm max, 5.8 mm max height. Specification first published on 2025-02-18, part number B2511, ED8×10-1.0H shielded type.

Shielded part. The windings sit inside a black housing that fully encloses them; the only exposed metal is the four gull-wing terminals protruding from the housing edge. There are no loose structures outside the coil, so the part can be placed, reflow-soldered, and cleaned like any other SMD block.

2. Construction and Materials

Core. Permalloy, ED8×10 laminations supplied by Jiangsu Hongyun Precision Industry. Permalloy is a high-permeability nickel-iron alloy whose advantage appears at the low end of the band: at 300 Hz it achieves inductance that a ferrite core of equal volume cannot, which is the foundation of the 1.0 H minimum at 1 kHz. The housing fully encloses the core, so the magnetic circuit is also shielded from surrounding stray fields.

Windings and magnet wire. Two independent windings with equal turns, wound with 2UEW-H magnet wire rated at 180 °C, covered under UL file E193774. The high-temperature rating allows the part to pass through a reflow oven while still holding its DC resistance window: 110 Ω ±10% between pins 1-2, and likewise 110 Ω ±10% between pins 3-4.

Insulation system. The bobbin is Sumitomo Bakelite PM9820 under UL file E41429, wrapped with PF(8) tape under UL file E165111, and treated with E962 impregnating varnish under UL file E335405. Each material is identified by supplier and file number, making the bill of materials auditable line by line — the section safety reviewers read first in the specification.

The housing serves as both shield and protective box. It encloses the magnetic circuit from exposure to external magnetic fields while protecting the fine-wire coil from damage during handling between the winding line and the reflow oven.

3. Features

Two independent 1:1 windings. Two separate windings with equal turns, each measured at 1 kHz / 0.3 V, both with a DC resistance of 110 Ω ±10% and a minimum inductance of 1.0 H. Equal turns sharing one core allow either side to drive or be driven, keeping the turns ratio within ±2%.

Permalloy core, ED8×10. The core is Permalloy, a high-permeability nickel-iron alloy, supplied by Jiangsu Hongyun Precision Industry as ED8×10 laminations. At 300 Hz, a Permalloy core achieves inductance that ferrite of equal volume cannot, which is the foundation of the 1.0 H minimum at 1 kHz.

Shielded construction. The windings sit inside a black housing that fully encloses them; the four terminals are formed as gull-wing shapes protruding from the housing edge. The housing shields the coil from adjacent magnetic interference and provides protection during handling.

Flat response across voice and program band. Referenced to 1 kHz, frequency response stays within ±0.12 dB from 300 Hz to 4 kHz — accurate enough that the transformer does not color the signal passing through it.

Independent windings, documented with data. Inter-winding insulation resistance is 100 MΩ minimum at 200 VDC, and inter-winding withstand voltage is 1,250 VDC/1 mA/60 s; both are outgoing acceptance items for every unit, not type-test declarations.

Traceable materials. Bobbin, magnet wire, tape, and impregnating varnish are each identified by supplier and UL file number; termination uses lead-free Sn-0.3Ag-0.7Cu solder, making the bill of materials auditable line by line.

4. Advantages

High permeability at low frequencies. Permalloy maintains permeability far better than ferrite at the lower end of the band, so this product achieves 1.0 H at 1 kHz within a 12.0×9.3×5.8 mm volume. That is the rationale for choosing this core over ferrite.

Symmetric, guaranteed by measured data rather than assertion. Both windings are specified at the same 110 Ω ±10% DC resistance and the same 1.0 H minimum, so the two sides are interchangeable in the circuit, and the turns ratio does not drift with mounting orientation.

±0.12 dB from 300 Hz to 4 kHz. This flat frequency response means the transformer is a pass-through component: whatever level goes in comes out, design margin is allocated elsewhere.

Planable package design. Body size is 12.0×9.3 mm, pins sit on a 14.0 mm span, pad layout is 5.08 mm row pitch × 0.7×1.05 mm — all dimensions are given numerically, so the pad pattern can be drawn directly from library data without tracing from a sample.

Clearly specified isolation performance. Inter-winding withstand voltage is 1,250 VDC tested at 1 mA for 60 s; insulation resistance is 100 MΩ minimum at 200 VDC; both are listed as acceptance criteria. Whenever a design must prove electrical isolation capability, these are the values testing agencies require.

Traceable material system. Bobbin, magnet wire, tape, and insulating varnish each carry independent UL file numbers; the magnet wire is rated at 180 °C, meeting equipment requirements that call for material declarations.

5. Application Areas

Low-frequency line and signal isolation. 1:1 coupling from 300 Hz to 4 kHz, covering voice, program signals, and signaling bands above them.

Audio inter-stage or inter-equipment isolation. When two circuits sit at different ground potentials, the transformer passes the signal while keeping the two grounds separate, cutting ground loops that can manifest as hum.

Compact SMD audio circuit boards. The 12.0×9.3 mm package body with four gull-wing pins can be placed and reflowed with the rest of the board, eliminating the need for hand-soldered through-hole mounting for a low-frequency Permalloy transformer.

Custom Permalloy solutions. When the standard 1:1 configuration does not fit, windings can be made to customer drawings or samples on the same core and housing, with an acceptance specification issued for that drawing.

On the circuit board, this device sits between the audio output and downstream circuitry; its job is to carry the signal across an isolation barrier without connecting the two grounds. Level and frequency response should not change; if they do, the device is being used as a matching element, and at that point the parameters in this table no longer describe what the circuit actually sees.

6. Specifications

The following data is the approved specification for the ZXY-B2511, reproduced faithfully from the published content.

6.1 Overview

6.2 Electrical Parameters

6.3 Mechanical Dimensions and PCB Pad Layout

6.4 Construction

6.5 Quality and Testing

7. Ordering

This part is ordered as ZXY-B2511. The core, bobbin, housing, and pins are defined as fixed parts of the design; windings and turns ratio can be customized per customer drawings or samples where the standard 1:1 configuration does not match the equipment. If the construction differs, please specify the turns ratio and impedance at the time of ordering so an acceptance table can be issued accordingly.

Brand/Manufacturer: ZXY, Shenzhen ZhiXiangYuan Electronics Co., Ltd. http://www.zxycoil.com