ZXY-EI19 Hard-Pin Audio Isolation Transformer, EI19 DIP Through-Hole, 1:1 / 1:5 / 1:11 Turns Ratio, 100 Hz-4.5 kHz, Hi-POT 500 V, 19.5 x 15 x 17 mm
ZXY-EI19 is an EI19 hard-pin audio isolation transformer in a DIP through-hole package, 19.5 × 15 × 17 mm on a 5 mm pin pitch. Four models share the footprint: EI1901 and EI1902 at 1:1, EI1904 at 1:5, EI1905 at 1:11. Inductance from 585 mH to 17 H at 1 kHz, DC resistance from 22 Ω, frequency range 100 Hz to 4.5 kHz, Hi-POT 500 V on every model.
- Four variants on one 19.5 x 15 x 17 mm body: 1:1, 1:5 and 1:11 turns ratio
- Frequency range 100 Hz - 4.5 kHz, the band the series is specified over
- Inductance 585 mH to 17 H at 1 kHz, 0.3 V signal, quoted as a minimum
- DCR from 22 ohm to 1.58 kohm, held to plus or minus 15 percent
- Hi-POT 500 V at 1 mA for 60 s on every model; DIP hard pins on 5 mm pitch
1. Product Name
ZXY-EI19 EI19 hard-pin audio isolation and voice / data coupling transformer. DIP through-hole package, 19.5 x 15 x 17 mm, 5 mm pin pitch, turns ratio 1:1, 1:5 or 1:11 depending on model, frequency range 100 Hz to 4.5 kHz, Hi-POT 500 V at 1 mA for 60 s.
Overview. The series is built around one body and one pin grid. What changes between the four models is the winding, not the package, so a board can be laid out once and populated with whichever ratio the circuit needs.
Physically the part is a laminated EI19 core with a taped winding on a black bobbin, three terminals in a block on the front face and two more on the opposite edge. The core edges stay exposed, which is what makes the stack visible in the photographs and lets the winding be inspected after assembly.
2. Feature
Four variants on one footprint. EI1901 and EI1902 at 1:1, EI1904 at 1:5 and EI1905 at 1:11, all in the same 19.5 × 15 × 17 mm body with the same 5 mm pin pitch.
100 Hz to 4.5 kHz. the working band for voice and data coupling, which is the range these parts are specified over rather than the full audio band.
Inductance quoted as a minimum. 1.2 H on both windings of the EI1901, 585 mH on both of the EI1902, 2.9 H and 150 mH on the EI1904, 266 mH and 17 H on the EI1905, all at 1 kHz with a 0.3 V signal.
DC resistance from 22 Ω. 22 Ω and 28 Ω on the EI1901, up to 1.58 kΩ on the second winding of the EI1905, every value held to ±15 %.
Hi-POT 500 V on every model. 1 mA leakage limit held for 60 s, the same rating across the series.
Hard pins, DIP through-hole. rigid terminals on a 5 mm pitch that hold the part in the board and take a standard solder joint without a carrier.
High-isolation core. a laminated EI19 core with the windings separated on the bobbin and the polarity brought out to the published schematic.
Yellow tape over the winding. the winding is taped and the core edges are left exposed, so the part can be inspected after winding.
Customized designs available. factory-direct supply from stock, with custom windings on request.
The series line on the artwork is worth reading closely: turns ratio 1:1, 1:5 and 1:11 with “various available”, inductance up to 1.2 H quoted against the EI1901, DC resistance as low as 22 Ω and Hi-POT 500 V. Those four numbers are the summary of the table in chapter 5.
3. Advantage
Protects the stage in front of it. the transformer isolates input from output, so a fault downstream cannot burn out the output of the equipment driving the line.
Removes grounding hum. two separated windings break the signal-path ground connection, which is what takes out the AC hum that system grounding produces.
Balanced and unbalanced lines. the same part reduces external interference in either arrangement.
One footprint, four variants. a design that moves from 1:1 to 1:5 or 1:11 keeps its land pattern, its panel cutout and its assembly drawing.
Rigid pins. through-hole terminals suit standard soldering and straightforward replacement, with no carrier or reflow profile to re-qualify.
Precision pin spacing. the 5 mm grid is what lets the part drop into an existing DIP footprint without a custom land pattern.
The pin grid is the practical advantage. A 5 mm pitch on a 19.5 mm body matches a standard DIP land pattern, so the part can replace a competitor device without a board revision, and the four ratios mean the same revision can serve a 1:1 isolation point and a 1:11 coupling point.
4. Application
The catalogue specification sheet lists four application areas for this part.
Communication equipment. line and voice circuits where two pieces of equipment must not share a ground.
Biomedical and medical devices. signal paths that need galvanic separation between the patient-side circuit and the rest of the instrument.
Telephone and fax equipment. coupling a line interface to the set electronics, in the 100 Hz to 4.5 kHz band the part is specified over.
Inductive (sensor) speakers. driving a high-impedance inductive load from a low-impedance amplifier output.
In each of these the useful property is the same: two circuits that must exchange a signal but must not share a reference. A telephone line interface, a patient-side electrode circuit and a sensor speaker all sit on the far side of that boundary.
5. Application Specifications
Electrical data at 25 degrees C, as published for the series. Inductance is a minimum value measured at 1 kHz with a 0.3 V test signal; DC resistance carries a plus or minus 15 percent tolerance.
5.1 Electrical specification by model
| Model | Turns ratio | L(1-2) | L(3-4) | DCR(1-2) | DCR(3-4) | Hi-POT |
|---|---|---|---|---|---|---|
| EI1901 | 1:1 | 1.2 H | 1.2 H | 22 Ω | 28 Ω | 500 V |
| EI1902 | 1:1 | 585 mH | 585 mH | 60 Ω | 75 Ω | 500 V |
| EI1904 | 1:5 | 2.9 H | 150 mH | 340 Ω | 12.5 Ω | 500 V |
| EI1905 | 1:11 | 266 mH | 17 H | 71 Ω | 1.58 kΩ | 500 V |
5.2 Construction and mechanical data
| Item | Value |
|---|---|
| Core | EI19 laminated core, described on the artwork as a high-isolation core |
| Package | DIP plug-in, through-hole hard pin, with precision pin spacing |
| Pin pitch | 5 mm, printed as 5*2 on the catalogue outline drawing |
| Body dimensions | 19.5 mm wide × 15 mm deep × 17 mm high, excluding pin length |
| Terminal rows | Three terminals on the front face, two on the opposite edge, as photographed |
| Winding | Two separated windings with the polarity marked on the published schematic, dots at pins 1 and 4 |
| Body finish | Yellow tape over the winding, black terminal blocks, laminated core exposed at the edges |
5.3 Terminals on the published schematic
| Terminal | Function |
|---|---|
| Terminal 3 | One end of the winding drawn on the left of the schematic |
| Terminal 1 | Other end of the same winding; polarity dot |
| Terminal 6 | One end of the winding drawn on the right |
| Terminal 4 | Other end of that winding; polarity dot |
6. Quality & Testing Assurance
Each parameter below is published with its test condition. Every model in the series carries the same dielectric withstand rating, and the part is marked CCC, CE and UL.
| Parameter | Test condition and specification |
|---|---|
| Inductance (L) | 1 kHz, 0.3 V test signal, quoted as a minimum value per model |
| DC resistance (DCR) | Tolerance ±15 % |
| Dielectric withstand (Hi-POT) | 500 V, leakage limit 1 mA, held 60 s, all four models |
| Turns ratio | 1:1 (EI1901, EI1902); 1:5 (EI1904); 1:11 (EI1905) |
| Reference temperature | 25 °C for all electrical parameters |
| Frequency range | 100 Hz to 4.5 kHz |
Brand / manufacturer: ZXY, Shenzhen Zhixiangyuan Electronics Co., Ltd. http://www.zxycoil.com