Re: will my house burn down?

Mark wrote:

putting a diode in series with the secondary does NOT push the core
towards saturation.. The PRIMARY still has AC on it and the
magnitizing current that flows in the primary keeps the core
centered.
(snip)

If the primary winding has zero resistance, then the voltage might remain pure AC, but this is not the case, especially for small transformers.

Loading the secondary with DC also loads the primary with DC, and that produces a voltage drop on half of the half cycles that is not there during the other half. That current drops voltage across the primary resistance, and that drop is subtracted from from the line voltage for those half cycles. This effect definitely unbalances the AC applied to the winding, and walks the core toward saturation.

Now, if you arrange another voltage drop for the unused half cycles that averages the same as the resistive drop during the loaded half cycles, and put that drop in series with the primary, you can bring the net voltage applied back to much closer to zero, and the transformer will be happy, once again. At least until the lamp burns out.
.

Relevant Pages

  • Re: DC magnetisation of transfromers and chokes.
    ... Afe is the core area in sq. ... one has to limit ac Bmax to 0.6T ... What would you regard as saturation problems? ... you consider voltage rather than current. ...
    (rec.audio.tubes)
  • Re: DC magnetisation of transfromers and chokes.
    ... Afe is the core area in sq. ... one has to limit ac Bmax to 0.6T ... What would you regard as saturation problems? ... you consider voltage rather than current. ...
    (rec.audio.tubes)
  • Re: will my house burn down?
    ... If the primary winding has zero resistance, then the voltage ... cycles that is not there during the other half. ... and walks the core toward saturation. ...
    (sci.electronics.design)
  • Re: What limits the current in an unloaded transformer?
    ... When I wound up the input voltage to the primary it got hotter. ... transformer got a lot hotter and before I knew it the primary ... At higher voltages the core will hit magnetic ... Most transformers are designed to run pretty close to core saturation ...
    (sci.electronics.basics)
  • Re: Modifying transformer
    ... I'm wondering if removing turns is a good idea? ... The core already saturates ... If it's already close to saturation, ... The voltage only went ...
    (sci.electronics.basics)