EL14 Horizontal Audio Isolation Transformer, Through-Hole PCB Mount, 300 Hz - 3.4 kHz, 1:1 Turns Ratio, EI1401 / EI1402, 16 x 8.5 mm
EL14 is a horizontal audio isolation transformer for through-hole PCB mounting: a precision ferrite core, a precision coil with the primary on pins 1-2 and the secondary on pins 4-3 under yellow tape insulation, and four pins in two rows. Two variants, EI1401 and EI1402, both 1:1 and both rated 1500 V at 1 mA / 60 s. 300 Hz to 3.4 kHz. Body 16 mm maximum length, 8.5 mm high.
- Turns ratio 1:1, primary on pins 1-2 and secondary on pins 4-3
- Precision ferrite core, yellow tape insulation, four through-hole pins
- Frequency range 300 Hz to 3.4 kHz, the telephone speech band
- EI1401 and EI1402, both rated 1500 V at 1 mA / 60 s
- Body 16 mm maximum length, 8.5 ± 0.3 mm high, pin rows 12 ± 0.3 mm apart
1. Product Name
EL14 horizontal audio isolation transformer for voice and data coupling, in the EI1401 or EI1402 variant. Precision ferrite core, primary on pins 1-2 and secondary on pins 4-3 under yellow tape insulation, four through-hole pins, 300 Hz to 3.4 kHz, body 16 mm maximum length and 8.5 mm high.
Overview. The coil sits on an insulated former inside the core window and is finished with yellow tape; the four pins come out of a header on the underside in two rows. Nothing protrudes above the core, which is what keeps the assembled height at 8.5 mm.
The horizontal package is chosen for the height, not the footprint: a low-profile board is usually short of vertical space above the surface, and a part that lies flat uses that space instead of adding to it.
2. Feature
Integrated isolation. the transformer protects the output stage of the preceding equipment from damage on the other side of the barrier, which is what an isolating part is for.
Voice and data coupling. wound to pass the signal between stages rather than to transfer power, so the audio band arrives intact and the earth path does not.
300 Hz to 3.4 kHz range. covers the telephone speech band, which is the band this part is specified for, and no wider claim is made for it.
Ground-loop hum removed. breaks the earth loop that generates the AC hum picked up when a system is grounded at two points.
Interference reduced both ways. lowers external interference pickup on balanced and on unbalanced transmission, so one part covers both wiring schemes.
The pair shows both faces that matter at assembly: the top, where the tape wrap and the outer core limbs are visible, and the underside, where the pin header sits. The pins are arranged 6 mm apart within a row and the rows 12 mm apart, so the plated holes fix the orientation of the part before any marking is read.
3. Advantage
Low-profile horizontal package. the body lies flat and stands 8.5 mm above the board, which is what lets it fit under a lid or between other components on a dense PCB.
Standard through-hole pin pattern. four pins in two rows, 6 mm apart within a row and 12 mm between rows, so the footprint is fixed and the part can be placed without a mechanical redesign.
Two builds under one outline. EI1401 and EI1402 share the pin pattern, the 1:1 ratio and the 1500 V rating, so the level can be set by choosing the variant rather than by changing the board.
Customised design available. the winding can be built to a customer specification where neither standard variant fits.
Factory-direct supply. standard parts are shipped from stock, which keeps the lead time off the critical path.
Neither view needs a callout to be read: the core limb runs the length of the body, the coil pads sit under the header, and the tape wrap covers the winding completely. That is the whole construction of the part - core, coil, insulation, pins - and there is no potted shell or bracket to allow for.
4. Application
Communication equipment. line and equipment side coupling where the two must stay isolated from each other.
Biomedical equipment. signal paths that have to be isolated from the patient-connected side, at the low level this part is specified for.
Telephone and fax equipment. the 300 Hz to 3.4 kHz band is the speech band these terminals carry, and the 1:1 ratio keeps the level across the barrier.
Induction speakers. coupling into a loop or induction coil where a direct connection would create a ground path.
Both views are of a board assembly: in the first the part is seated with all four pins through the board, in the second the pins are being soldered. The 8.5 mm stand-off is what the two show - the body clears the components beside it, so nothing has to be moved to make room.
5. Application Specifications
The specification below is the data declared for this model: product data, the electrical table per variant at 25 °C, outline and pin dimensions, and the pin assignment.
5.1 Product specification
| Item | Value |
|---|---|
| Product name | EL14 horizontal audio transformer |
| Model | EL14, horizontal package |
| Variants | EI1401 and EI1402, as listed in the electrical specification |
| Product category | Audio isolation / voice and data coupling transformer |
| Package | Horizontal through-hole, PCB mount |
| Windings | Primary on pins 1-2, secondary on pins 4-3 |
| Turns ratio | 1:1 |
| Frequency range | 300 Hz - 3.4 kHz |
| Core | Precision ferrite core |
| Coil | Precision winding, primary 1-2, secondary 4-3 |
| Insulation | Yellow tape insulation |
| Terminals | 4 through-hole pins, 2 primary and 2 secondary |
| Reference temperature | 25 °C |
| Design service | Customised designs available |
5.2 Electrical specification, two variants, 25 °C
Inductance is measured at 1 kHz with a 0.3 V test signal as a minimum; DC resistance carries a tolerance of plus or minus 15 percent; dielectric withstand is 1500 V with a 1 mA leakage limit held for 60 s. The column labels DCR(1-3) and DCR(4-5) are the ones printed on the source sheet; see the note below.
| Model | Turns ratio | L(1-2) | L(3-4) | DCR(1-3) | DCR(4-5) | HI-POT |
|---|---|---|---|---|---|---|
| EI1401 | 1:1 | 780 mH | 780 mH | 260 Ω | 260 Ω | 1500 V |
| EI1402 | 1:1 | 1.0 H | 1.0 H | 290 Ω | 290 Ω | 1500 V |
5.3 Outline and pin dimensions
| Parameter | Specification |
|---|---|
| Body length | 16 mm maximum |
| Height | 8.5 ± 0.3 mm |
| Pin spacing within a row | 6 ± 0.3 mm |
| Pin row spacing | 12 ± 0.3 mm |
| Terminals | 4 through-hole pins, 2 per row |
5.4 Pin assignment and winding polarity
| Pin | Winding | Marking |
|---|---|---|
| Pin 1 | Primary, start of winding | Polarity dot |
| Pin 2 | Primary, other end | - |
| Pin 4 | Secondary, start of winding | Polarity dot |
| Pin 3 | Secondary, other end | - |
Primary winding on pins 1-2, secondary on pins 4-3. The polarity dots mark the start of the primary winding at pin 1 and the start of the secondary at pin 4, so the winding sense is fixed by the footprint.
6. Quality & Testing Assurance
The limits below are the acceptance limits the specification sheet states for both variants at 25 °C. They share one set of limits except for the inductance and resistance values themselves.
| Test item | Specification | Condition |
|---|---|---|
| Turns ratio | 1:1 | - |
| Primary inductance, L(1-2) | 780 mH minimum on EI1401, 1.0 H on EI1402 | 1 kHz, 0.3 V |
| Secondary inductance, L(3-4) | 780 mH minimum on EI1401, 1.0 H on EI1402 | 1 kHz, 0.3 V |
| DC resistance, DCR(1-3) | 260 Ω on EI1401, 290 Ω on EI1402, tolerance ±15% | 25 °C |
| DC resistance, DCR(4-5) | 260 Ω on EI1401, 290 Ω on EI1402, tolerance ±15% | 25 °C |
| Dielectric withstand, HI-POT | 1500 V | 1 mA, 60 s |
| Operating frequency range | 300 Hz - 3.4 kHz | - |
Insulation is yellow tape over the winding, and the terminals are through-hole pins, two per winding, which is what lets the part be soldered rather than wired.
Brand / manufacturer: ZXY, Shenzhen Zhixiangyuan Electronics Co., Ltd. and Huizhou Zhixiangyuan Technology Co., Ltd. http://www.zxycoil.com