... PUSH-PULL WAY,.APPLYING FOR TYPICAL TRANSFORMER CONSTRUCTION. * EI,EE,EF CORE TRANSFORMERS HAVE A SIMPLE CONSTRUCTION,LOW MANUFACTURE COST AND ... THE COMMON MODEL OF EF CORE TRANSFORMER INCLUDE EF-16,EF-20,EF- 25, EF-32 ETC. * THE COMMON MODEL OF EF CORE TRANSFORMER INCLUDE EI-16 ... ,EI-19,EI- 25, EI ...