Help - Isolation transformer

Discussion in 'General Electronics Chat' started by bloguetronica, May 5, 2007.

  1. bloguetronica

    Thread Starter AAC Fanatic!

    Apr 27, 2007
    Well, I need an isolation transformer with the following specifications:

    220V AC

    Secondaries (isolated from each other, not tapped):
    230V AC (could be 460V AC, but I think those don't exist, so I will use a full wave voltage doubler instead)
    6.3V AC (300mA minimum, for the heater)

    This transformer is for an oscilloscope CRT. I think if I got a 1:1 isolation transformer, I would be glad (I can add another transformer to supply 6V to the heater). The objective here is to have 600V DC (230VAC x 2 x 1.414VDC/VAC = 650VDC).

    Could anyone recommend a trafo model or a manufacturer?
  2. thingmaker3

    Retired Moderator

    May 16, 2005
  3. lightingman

    Senior Member

    Apr 19, 2007
    Yes I am sure I have some..I will look on Monday..If I have one, you would be welcome to it..But where are you..Daniel.
  4. awright

    AAC Fanatic!

    Jul 5, 2006
    If you use a separate transformer for the CRT filament, be sure that it is insulated for the DC voltage to ground that it will be subjected to. An ordinary off-the-shelf filament transformer will not stand up to the DC voltage.

  5. bloguetronica

    Thread Starter AAC Fanatic!

    Apr 27, 2007
    Well, in my situation, isolation will be really needed. But I prefer a "plate and filament" transformer (or a "valve power" transformer), since those are more adequate. I will use a 500V AC secondary and forget about the voltage doubler.
    I need a transformer suitable for 230V AC (I think I cannot use one for 220V AC, and a trafo for 240V AC would be ineficient).