ZXY DU124 Microphone Transformer, Lead-Wire Type, 20 Hz - 20 kHz, Turns Ratios 1:4 / 1:7 / 1:12, Laminated EI Core, 16.5 x 12.0 x 25.0 mm, Four Pre-Tinned Leads

1. Product Name

ZXY DU124 microphone transformer, fly-lead type, with selectable turns ratios of 1:4, 1:7, or 1:12. Laminated EI core, windings wrapped with high dielectric strength yellow polyester film tape, four pre-tinned leads with UL AWM-rated insulation, nominal lead length 40 ± 2 mm, body dimensions 16.5 x 12.0 x 25.0 mm, frequency range 20 Hz to 20 kHz.

Overview. This device uses a laminated EI core with a lamination width of 7.5 mm, and the winding occupies 13.0 mm of the 25.0 mm body height. The front dimension is 16.5 mm and the side dimension is 12.0 mm, so it takes up a small footprint with a taller columnar profile in the layout.

Four leads exit from the bobbin rather than pins. This is the core purpose of this package style: after the mechanical design is finalized, it can still be routed into a microphone housing, a flying lead harness, or existing assemblies, whereas pin-type devices would require a PCB design change.

2. Features

Isolates and protects front-end circuits. The transformer couples signals through a non-conductive path, so a fault or DC bias on one side will not damage the output stage driving it.

Voice and data coupling. The windings are designed for signal coupling in voice and data paths, not power transfer, which is the application range covered by the 20 Hz to 20 kHz band.

20 Hz to 20 kHz frequency range. Covers the full audio band, so the device can be used in microphone lines, preamplifier inputs, or line-level interfaces without becoming the bandwidth-limiting element.

Suppresses ground loop hum. Isolation breaks the loop formed when two devices are grounded separately, which is where AC hum in the signal chain typically originates.

Balanced and unbalanced applications. Reduces external interference in both configurations, so the same device works in balanced microphone lines as well as unbalanced lines inside a chassis.

Fly-lead termination. Four pre-tinned leads, 40 ± 2 mm long, replace PCB pins for routing into microphone housings, harnesses, or existing assemblies without requiring solder pads.

Low-distortion, wide-response windings. Tuned to maintain both voice clarity and audio fidelity, the trade-off a microphone transformer must make.

Laminated EI core. Precision-laminated construction, wrapped with high dielectric strength yellow polyester film tape to insulate the windings from the core edges.

The detail view shows the three key elements that determine the device's performance: the leads are pre-tinned with UL AWM-rated insulation, the core is made of stacked laminations rather than solid construction, and the windings are wrapped with high dielectric strength yellow polyester film tape before the core is installed. The 1500 V dielectric withstand rating is tested against this tape layer.

3. Advantages

Three turns ratios, one series. 1:4, 1:7, and 1:12 cover boost requirements from moderate to high-ratio microphone matching, so one qualified device series covers an entire product line.

Routing flexibility. Lead-wire devices can be routed after the mechanical design is fixed, which pin-type transformers on a PCB typically cannot.

Complete electrical documentation. Inductance, DC resistance, and dielectric withstand voltage at 25 °C are published for each turns ratio, so selection can be made by specification rather than by trial.

Consistent dielectric margin. All three variants are rated at 1500 V with a 1 mA leakage limit for 60 seconds, so changing turns ratios does not require re-qualifying isolation ratings.

Tape insulation over windings. High dielectric strength polyester film between the windings and the core carries the withstand voltage rating.

Pre-tinned leads. Solderable directly without stripping or tinning on the workbench, with UL AWM-rated insulation on the leads.

Custom design support. Windings can be adapted to target turns ratios, levels, or dimensions; standard models are available for factory-direct supply and stock.

Read the schematic before wiring. RED and BLACK are on the same winding with the polarity dot on the BLACK side; BLUE and YELLOW are on the other winding with the polarity dot on the BLUE side. The drawing indicates the pairs and polarity dots but does not specify which is the primary, so confirm the pairs from the drawing and verify the intended side with the factory before fixing the wiring order.

4. Applications

Microphones. Lavalier, camera, and instrument microphones, with the transformer mounted inside the microphone body or in the cable connector end.

Microphone preamplifiers and isolation modules. As an input transformer or isolation element in preamp or channel modules.

Audio systems. Signal isolation and noise cancellation in hi-fi speakers, home theater, and car audio, where separate grounds introduce hum into the signal.

Communication equipment. Signal coupling in telephones, fax machines, VoIP terminals, and modems, where the line side must remain isolated from the equipment side.

Industrial and broadcast systems. Audio signal isolation and transmission in public address and conference systems, including runs between rooms and equipment racks.

The two images show the same real-world scenario: the transformer sits at the boundary between two circuits that must not share a common conductor. On the breadboard, it is the element between the signal source and the measurement side; on the board assembly, it is soldered by its leads next to the circuit it isolates. Neither mounting method requires solder pads, which is why the same device appears in both scenarios.

5. Application Specifications

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

5.1 Product Specifications

5.2 Electrical Specifications, Three Turns Ratio Variants

Inductance is measured at 1 kHz, 0.3 V, and is a minimum value; DC resistance tolerance is ±15%; dielectric withstand voltage is 1500 V, 1 mA leakage limit, for 60 seconds.

5.3 Dimensions

5.4 Construction and Lead-Out

6. Quality and Testing Assurance

Each unit is inspected to the following limits, taken from the same datasheet that provides the electrical parameter tables. The three turns ratio variants share one set of limits, except for the inductance and resistance values themselves.

Winding insulation uses high dielectric strength yellow polyester film tape; fly leads are pre-tinned with UL AWM-rated insulation and are solderable directly.

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