EI-4120W-5409 Dual-Voltage Power Transformer - 110 V / 220 V Input | 12 V-0-12 V and 24 V 250 mA Output | EI-41 Silicon Steel Core | Chassis Mount

1. Product Name

EI-4120W-5409 dual-voltage power transformer, chassis mount, EI-41 silicon steel core, 110 V / 220 V dual primary, 12 V-0-12 V and 24 V 250 mA secondary, 8 solder lug terminals.

This device features an EI-41 laminated core housed in a flame-retardant bobbin, enclosed in a drawn metal housing with two integrated mounting flanges. The nameplate on the housing indicates the model number and terminal functions, allowing wiring directly from the device body.

2. Product Features

Dual-Voltage Primary — Two 110 V windings, parallel for 110 V mains, series for 220 V mains (terminals 1-4 for 0-220 V).

Center-Tapped Secondary — Terminals 5-7-8 deliver 12 V-0-12 V, or terminals 5-8 deliver 24 V, rated at 250 mA.

EI-41 Silicon Steel Core — High magnetic permeability, low eddy current losses.

Eight Solder Lug Terminals — 6.3 x 0.8 mm lugs arranged in a 4 + 4 layout for easy wire soldering and chassis connection.

Dual Mounting Flanges — 44.0 mm hole spacing with 4.5 x 6.5 mm mounting holes for secure chassis installation.

Flame-Retardant Bobbin — Excellent high-temperature resistance for enhanced safety.

Metal Housing — Sealed construction with a printed nameplate indicating winding configuration.

High Isolation — Primary and secondary windings are physically separated for circuit isolation.

3. Product Advantages

One Device, Two Mains Voltages — Dual primary windings allow a single part number to cover both 110 V and 220 V markets.

Two Output Configurations — Center-tapped secondary provides 12 V-0-12 V or 24 V output without additional components.

Low Distortion — Silicon steel laminations and stable winding construction ensure low waveform distortion.

Thermal Stability — Flame-retardant bobbin and metal housing support high-temperature performance under continuous use.

Consistent Performance — Every unit maintains identical electrical characteristics across production batches.

Serviceable Connections — Solder lug terminals allow field re-wiring and chassis wiring without a PCB.

4. Application Areas

Audio Equipment Power — Steps down mains voltage to power analog and digital supply rails in audio equipment.

DAC and Preamplifier Construction — Transformer power supply for reference-class DAC and preamplifier chassis.

Power Supply Filter Boards — Board-level power supply for equipment with separate filter stages.

General Chassis-Mount Equipment — Any application requiring 110 V / 220 V input with isolated 12 V or 24 V / 250 mA output rails.

The transformer is mounted on the chassis and connected to the circuit board via leads, keeping primary and secondary circuits isolated from each other. The safety ground is carried by the chassis rather than the signal ground.

5. Application Specifications

All dimensions are in millimeters and follow standard chassis-mount conventions.

The electrical specifications printed on the nameplate are as follows:

6. Quality and Testing Assurance

Verification — Rigorous performance verification performed at the audio R&D and quality testing workbench.

Dual-Voltage Testing — Every unit is tested under both 110 V and 220 V primary connections.

Load Stability — Continuous load stability checks at the rated 250 mA output.

Compliance Certification — CCC, CE, RoHS, and UL marks are printed on the product exterior.