ferroresonant transformer

Hi,

Could anyone tell a bit about ferroresonant transformers ?
I gather its some sort of regulating device.

Cheers, John

My understanding is that it is constructed of materials that vary in electro-magnetic characteristics in a way that helps maintain a more constant output voltage.

The ferroresonant stabiliser transformer designed for AC voltage stab. It contains a separated winding with parallel condenser (tank circuit for mains frequency)

Sounds interesting.
Tuned to 50 c/s well, 60 in some places.

I will have to read a bit more about this.
So wheres the stabilising effect?

This is an old circuit of mains-stab for TV.(1980)
Tr1: E-I 130 core, pack 50mm, air-gap 1.5mm
n1 370 turns, 1.5mm wire
n2 68 turns, 1.5mm wire
Tr2: SM 102/B (hypersil)
n1 133 turns 1.5mm wire
n2 187 turns 1.2mm wire
Unfortunately with my bad english i can't explain the function. This circuit can handle 300VA load, while the input changed from 165 to 240V, the output voltage change remain until 10%. The output waweform distorted trapezoid, because Tr2 working in saturated mode.