ZXY EI42-110V-28.3V Low-Frequency Step-Down Transformer - 110 V AC 60 Hz to Dual 28.3 V AC | 2 x 70 mA | PCB Through-Hole Mounting | 1000 V Dielectric Strength

1. Product Name

ZXY EI42-110V-28.3V (ZXY Part No. B2361) PCB-mounted low-frequency step-down transformer. EI42 laminated core using 0.5 mm H18A electrical steel, two 110 V AC / 60 Hz primary windings and two independent 28.3 V AC secondary windings, maximum overall dimensions 43.5 x 36.3 x 31.0 mm, DIP through-hole package.

IdentificationCustomer part name EI42-110V-28.3V; ZXY part number B2361; Approval specification 20220922001, revision A/0. The cover is printed with T2382TX / T023370-8 and date code, per the marking field of the approved drawing.

This part is wound as a step-down transformer for 110 V / 60 Hz lines: two identical primary windings, 2365 turns of 0.08 mm wire, connected in parallel on terminals 1-6 and 2-7; two secondary windings, 617 turns of 0.14 mm wire, brought out to terminals 8-9 and 13-14. Each secondary outputs 28.3 V AC at no load and 21.6 V AC at 70 mA load, so one part can provide two isolated low-voltage rails, or a single rail with double current when the two secondaries are paralleled.

2. Product Overview

B2361 is a board-mounted 110 V AC step-down isolation transformer. The two primary windings are wound identically and connected in parallel to the 110 V / 60 Hz line; the two secondaries are independent, so a single part produces two electrically isolated low-voltage rails. Since the magnetic circuit carries energy and the circuit is isolated, the low-voltage side remains separated from the mains side, and ground interference does not enter downstream circuits.

The no-load current at rated input remains within 10 mA, and no-load loss within 0.8 W, keeping standby power consumption and internal heat of continuously powered devices low. The winding is mounted on a PBT MB2830 bobbin, wrapped with JY-133 tape, vacuum-impregnated with E962 varnish, and enclosed by 0.5 mm H18A electrical steel EI42 core. This construction classifies the insulation as B/F class (130 / 155 °C), suppresses mechanical noise under load, and terminates with rigid tinned pins for wave soldering or manual soldering.

3. Feature

Dual independent primary windings — Terminals 1-6 and 2-7, rated 110 V AC / 60 Hz, so the part can be powered from a single or dual line.

Two independent secondary windings — Terminals 8-9 and 13-14, each 28.3 V AC ±5% at no load, 21.6 V AC ±5% when supplying 70 mA load.

Low standby power consumption — Maximum no-load current 10 mA and no-load loss 0.8 W at 110 V AC / 60 Hz.

EI42 laminated core — 0.5 mm H18A electrical steel laminations, stacked and clamped by the bobbin cheeks.

B/F class insulation system — Materials rated 130 °C / 155 °C throughout the winding.

1000 V dielectric withstand voltage — AC 1000 V / 50 Hz applied between primary and secondary, primary and core, secondary and core, leakage current limit 5.0 mA, held for 60 s.

Vacuum-impregnated, taped bobbin — JY-133 tape and E962 varnish secure the winding and suppress mechanical noise.

Rigid DIP pins — Thickness 0.8±0.1 mm, length 5.0±0.5 mm, row spacing 20.0±0.5 mm, suitable for wave soldering or manual soldering.

Lead-free termination — Solderable pins are Sn-0.3Ag-0.7Cu.

Compliance — CE, UL, RoHS, and CCC certified, manufactured with UL-recognized materials (see Table 4).

4. Advantage

Provides two isolated 28.3 V outputs from a single 110V primary — No second transformer needed on the board.

Transformer isolation — Isolates the low-voltage side from the mains side and limits interference reaching downstream circuits.

Low 10mA no-load current and 0.8W no-load loss — Reduces standby power and heat in sealed enclosures.

Vacuum impregnation with taped PBT bobbin — Suppresses mechanical noise under load.

43.5 x 36.3 mm footprint — Fits standard board layouts, rigid pins withstand automated insertion and soldering.

Published certified data — Winding data, dimensions, and withstand voltage are fixed in specification 20220922001, so incoming inspection can be checked against the drawing.

5. Application

B2361 is designed as a board-mounted 110V AC step-down and isolation transformer. Typical uses include low-voltage power supply and isolation stages in audio equipment, instrumentation, and control electronics that require one or two isolated 28.3V AC outputs from a 110V/60Hz line; board-level step-down for control boards and relay drives; and interstage isolation where the mains side and low-voltage side must remain separate.

6. Application Specifications

Electrical ratings are as published in the certification specification and refer to 60Hz rated input at 25°C ambient temperature.

6.1 Electrical Specifications

6.2 Winding Construction

6.3 Outline Dimensions (Unit: mm)

6.4 Bill of Materials

6.5 Certification Data Notes

7. Quality and Test Assurance

Each unit undergoes appearance and insulation resistance inspection, and measurements of primary excitation current, primary excitation loss, secondary no-load voltage, and secondary loaded voltage at 70 mA under 110 V AC / 60 Hz. Dielectric withstand test applies AC 1000 V, 50 Hz, with a leakage current limit of 5.0 mA, held for 60 seconds.

Five sample units archived with the approval specification show all parameters far better than limits: excitation current 3.4 mA to 3.5 mA (limit 10 mA), excitation loss 0.22 W (limit 0.8 W), no-load output voltage 28.25 V to 28.35 V, and loaded output at 70 mA 21.4 V to 21.7 V. Production is executed according to approval specification 20220922001 (Revision A/0).