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 DIP Mount | 1000 V Hi-Pot

1. Product Name

ZXY EI42-110V-28.3V (ZXY part number B2361) PCB-mount low-frequency step-down transformer. EI42 laminated core of 0.5 mm H18A electrical steel, two 110 V AC / 60 Hz primary windings and two independent 28.3 V AC secondary windings, 43.5 x 36.3 x 31.0 mm maximum body in a DIP through-hole package.

Identification. Customer part name EI42-110V-28.3V; ZXY part number B2361; approval specification 20220922001, edition A/0. The cover is printed T2382TX / T023370-8 followed by a date code, as specified in the marking field of the approval drawing.

The part is wound as a step-down transformer for 110 V / 60 Hz lines: two identical primary windings of 2365 turns at 0.08 mm wire are paralleled on the 1-6 and 2-7 terminals, and two secondary windings of 617 turns at 0.14 mm wire leave on 8-9 and 13-14. Each secondary gives 28.3 V AC at no load and 21.6 V AC into a 70 mA load, so one part supplies two isolated low-voltage rails, or one rail at double current when the two secondaries are paralleled.

2. Product Overview

The B2361 is a board-mounted 110 V AC step-down and isolating transformer. The two primaries 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 galvanically isolated low-voltage rails. Because the magnetic path carries the energy and the galvanic path is broken, the low-voltage side stays separated from the mains side and ground-borne interference is kept away from downstream circuitry.

No-load current stays within 10 mA and no-load loss within 0.8 W at rated input, which keeps standby consumption and internal heating low in equipment that is powered continuously. The winding sits on a PBT MB2830 bobbin, is taped with JY-133 and vacuum-impregnated with E962 varnish, and is closed over a 0.5 mm H18A electrical steel EI42 core. That construction fixes the insulation at Class B/F (130 / 155 °C), holds the mechanical hum down under load, and ends in rigid tinned pins for wave or hand soldering.

3. Feature

Dual independent primary windings — terminals 1-6 and 2-7, rated 110 V AC at 60 Hz, so the part can be fed from one line or from two.

Two independent secondaries — terminals 8-9 and 13-14, each 28.3 V AC ±5% at no load and 21.6 V AC ±5% while delivering 70 mA.

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

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

Class B/F insulation system — 130 °C / 155 °C rated materials throughout the winding.

1000 V dielectric withstand — AC 1000 V at 50 Hz with a 5.0 mA leakage limit, held 60 s, between primary and secondary, primary and core, secondary and core.

Vacuum-varnished, taped bobbin — JY-133 tape and E962 varnish lock the winding and suppress mechanical hum.

Rigid DIP pins — 0.8 ± 0.1 mm thick, 5.0 ± 0.5 mm long, on a 20.0 ± 0.5 mm row spacing for wave or hand soldering.

Lead-free terminations — Sn-0.3Ag-0.7Cu solderable pins.

Compliance — CE, UL, RoHS and CCC, built from UL-listed materials (Table 4).

4. Advantage

Two isolated 28.3 V rails from one 110 V primary — removes the need for a second transformer on the board.

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

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

Vacuum impregnation of a taped PBT bobbin — suppresses mechanical hum under load.

43.5 x 36.3 mm footprint — fits standard board outlines, and the rigid pins withstand automated insertion and soldering.

Published approval data — winding data, dimensions and Hi-POT values are fixed in specification 20220922001, so incoming inspection can be checked against the drawing.

5. Application

The B2361 is built as a board-mounted 110 V AC step-down and isolating transformer. Typical uses are low-voltage supply and isolation stages in audio equipment, instrumentation and control electronics that need one or two isolated 28.3 V AC rails from a 110 V / 60 Hz line, board-level step-down for control boards and relay drivers, and inter-stage isolation where the mains side must stay separated from the low-voltage side.

6. Application Specifications

Electrical ratings are those published in the approval specification and are referred to the 60 Hz rated input at 25 °C ambient.

6.1 Electrical specification

6.2 Winding construction

6.3 Outline dimensions (unit: mm)

6.4 Material list

6.5 Notes on the approval data

7. Quality & Testing Assurance

Every unit is inspected for appearance and insulation resistance and measured for primary exciting current, primary exciting loss, secondary no-load voltage at 110 V AC / 60 Hz and secondary load voltage at 70 mA. Dielectric withstand is applied at AC 1000 V, 50 Hz, with a 5.0 mA leakage limit held for 60 s.

The five-sample record filed with the approval specification shows a wide margin against the limits: exciting current 3.4 mA to 3.5 mA against a 10 mA limit, exciting loss 0.22 W against 0.8 W, no-load output 28.25 V to 28.35 V, and output at 70 mA from 21.4 V to 21.7 V. Manufacturing runs to approval specification 20220922001, edition A/0.