... :Typical: PQ 2020, 2016, 2625, 3230, 3535, 4040 and 5050 EI, EE series: EI, EE-5.0, 8.3, 10, 13, 16, 19 ... and 49 ETD series: ETD-29, 34, 39, 44, 49, 54 and 59 EFD-15, 20, 25 and 30 introduction of transformers EC, EE ... .EI and PQ type high frequency switch ...