ZXY-DU135 Microphone Transformer, Flying Lead Audio Isolation Type, 50 Hz – 20 kHz, Turns Ratios 1:1.2 / 1:2 / 1:5, Laminated Silicon Steel Core, 19.5 x 13.0 x 16.5 mm

1. Product Name

ZXY DU135 microphone transformer, flying lead type, available with turns ratios of 1:1.2, 1:2, or 1:5. Laminated silicon steel core, copper wire wound on a nylon bobbin and wrapped with insulation, four color-coded leads, frequency range 50 Hz to 20 kHz, body length 19.5 mm, height 16.5 mm, width 13.0 mm.

Overview. The core is stacked from silicon steel laminations, and the coil is wound on a nylon bobbin and wrapped before the core is fitted. The product has no pins: four leads exit from the bobbin, with black and red as one winding pair and blue and yellow as the other.

Flying-lead versions can be routed flexibly into a microphone cavity, harness, or assembly once the mechanical design is fixed, whereas pin-style transformers may force a board revision. The catalog describes this lead configuration as accommodating multiple mounting and routing scenarios, which is the practical reason for selecting this form over a pin-equivalent part number.

2. Features

Electrical isolation and removal of mains interference. The transformer couples audio signals while providing no conductive path between the two circuits, and in doing so eliminates AC mains frequency interference.

Voice and data coupling. The windings are designed to couple voice and data signals between stages and between balanced and unbalanced circuits, not to transfer power.

50 Hz to 20 kHz frequency range. Covers the voice band and the full audio band above it, so the device can be placed in a microphone line or coupling stage without limiting bandwidth.

Eliminates ground loop hum. Removes hum generated when systems are grounded, a common source of noise in signal chains made up of independently grounded equipment.

Reduces interference in both directions. The isolation design reduces external interference pickup in both balanced and unbalanced transmission, with a single device covering both wiring schemes.

Flying lead termination. Uses four color-coded leads instead of pins, suitable for mounting and routing scenarios where no solder pads are available or where positions are already fixed.

Low distortion, wide response. Designed to strike a balance between voice clarity and audio reproduction fidelity, a trade-off that microphone transformers must make.

Laminated silicon steel core. Uses stacked laminations rather than a solid block, with the coil wound on a nylon bobbin and wrapped before the core is fitted.

The detail view distinguishes the three elements that define the device's performance: the lead exit and its wire connections, the laminated core, and the insulation wrap on the coil. This wrap is the insulation layer measured for the 1500 V withstand rating.

3. Advantages

Three turns ratios in one body. 1:1.2, 1:2, and 1:5 share the same outline dimensions and the same 1500 V dielectric rating, so one qualified outline covers the entire product family.

Routing flexibility. Flying-lead versions can be routed after the mechanical design is settled, something pin-style transformers cannot do.

Published electrical parameters. Inductance and DC resistance are given per turns ratio at 25 °C, allowing selection by numerical values rather than by listening judgment alone.

Consistent dielectric margin. All three versions are rated at 1500 V with a leakage current limit of 1 mA for 60 s, so the isolation specification does not change with the turns ratio.

Insulation wrap on the coil. The winding is wrapped before the core is fitted, and this layer is what the withstand rating is measured on.

Color-coded leads. Black, red, blue, and yellow are used to identify windings at the workbench and in the harness, with the polarity dot on the schematic as the final reference.

Custom designs and stock availability. Windings can be adapted to a target turns ratio or level, and standard versions are available ex stock directly from the factory.

Read the schematic before wiring. Black and red are on the same winding with the polarity dot at the black end; blue and yellow are on the other winding with the polarity dot at the blue end. The drawing identifies the wire pairs and polarity dots but does not label which side is the primary, so confirm the wire pairs from the drawing and verify the intended side before finalizing the wiring order.

4. Applications

Professional audio equipment. Lavalier microphones, camera microphones, instrument microphones, microphone preamplifiers, and audio isolation modules.

Audio systems: signal isolation and noise elimination for high-end loudspeakers, home theater systems, and automotive audio systems.

Communication equipment: signal coupling in telephones, fax machines, VoIP terminals, and modems, keeping the line side and equipment side electrically isolated.

Industrial and broadcast systems: audio signal isolation and transmission in public address and conference systems, including wiring across rooms and equipment racks.

The two mounting views show the same thing in practice: the transformer sits at the boundary between two circuits that must not share a conductor. Inside the chassis, it connects via leads next to the supply it isolates; on the board, it is soldered at the lead ends. Neither mounting method requires dedicated pads, so the same device can appear in both scenarios.

5. Application Specifications

The following specifications are the declared data for this model: product data, electrical parameter table by turns ratio at 25 °C, outline dimensions, and construction.

5.1 Product Specifications

5.2 Electrical Specifications, Three Turns Ratio Versions, 25 °C

Inductance is measured at 1 kHz, 0.3 V test signal, and is a minimum value; DC resistance tolerance is ±15%; dielectric withstand is 1500 V, leakage current limited to 1 mA for 60 s.

5.3 Outline Dimensions

5.4 Construction and Leads

6. Quality and Test Assurance

The following limits are those specified in the model's specification sheet. All three turns ratio versions share one set of limits, except for the inductance and resistance values themselves.

The winding insulation is the insulation wrap on the coil, and the leads are color-coded, allowing windings to be identified without a multimeter.

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