EI transformer

EI transformer is a traditional transformer. The core of EI transformer is combined by lamination E and I, so it is called EI transformer or laminated transformer. EI transformers are widely used in electronic equipment, not only it is an old type transformer, but also it is an economic transformer. It is usually used as power transformer at 50-60Hz. In audio applications, EI transformer is commonly used as tube power transformer and output transformer. Because there is air gap between E lamination and I lamination, and the air gap is easily adjustable by filling some medium, it is suitable to make output transformers and chokes. This is why you see many audio output transformers and chokes are designed in EI transformer.

EI transformer lamination transformeri


EI transformer is a traditional transformer, born very earily. The structure of EI transformer is simple and widely known. Untill now, most of transformer factories can manufacture EI transformers, and production process is mature.


EI transformer has a long history. It is easy to find EI transformer components in the market, and lead a economic solution for the project. You even needn't spend much to have one.

EI lamination

H50, H18, Z11 would be adopted for EI transformers. Material has undergone annealing treatment by high temperature, Hi-B, low exciting current, and has consistence performance.

EI lamination
ofc copper wire

Copper wire

OFC(Oxygen Free Copper) copper wire applied in our EI transformers. OFC has no hydrogen embrittlement, and has a high conductivity. It is commonly used in audio equipment, vacuum electronic components, wire and so on.


From picking up a core, calculating an appropriate copper wire to delivery test, every single EI transformer should undergo very strict processing flow. Only strict processing technics can guarantee a high quality EI transformer. And only transformers from regular manufacturers can guarantee strict processing technics.

EI transformer

EI Transformer Series

Power(VA) Dimension(mm) Weight(kg)
5 65×39×36 0.24
8 77×43×43 0.37
10 87×43×51 0.42
15 87×48×51 0.50
20 87×51×51 0.58
25 87×59×51 0.66
30 87×64×51 0.62
35 95×50×59 0.75
45 95×54×59 0.86
50 94×63×59 0.92
60 96×76×59 1.14
80 77×86×70 1.90
90 86×84×78 2.10
100 86×86×78 2.41
120 96×86×86 2.60
150 96×94×86 2.95
200 96×101×86 3.50
250 96×106×86 3.90
270 105×104×93 4.18
320 114×108×103 5.50
400 134×115×115 6.70
500 134×125×115 8.10
700 134×135×115 9.38
800 134×140×115 10.10
900 150×145×130 11.80
1000 150×155×130 12.80
1500 150×175×130 16.00
EI transformer dimension

Custom service

We supply custom made EI transformers to satisfy special requests and needs. Please get in touch with us through the contact information on our website. We can design and manufacture transformers suitable for you.