Feedback from high power supply without transformer

How can i take feedback from high power without transformer...As i seen there are many resistive and capacitive power supply they down power without transformer but they give stable output....But i don't want stable output.i want to generate error and then want to feed to conroller...In short change in input high power supply 230v its down to 20v .............if input power is changed to 245 its down to 35v(suppose like this ).....

I don't understand what you are looking for.
Can you explain a bit more?
Are you after power or just a signal ?

i want to make sevo controlled voltage stabilizer for 3 phase power supply........it is 415v... i want to take feedback and want to give feedback to controller...How can i step down voltage except transformer......?

i want to make sevo controlled voltage stabilizer for 3 phase power supply........it is 415v... i want to take feedback and want to give feedback to controller...How can i step down voltage except transformer......?

vijay.parmar1992

You only need a very small current, so you could use a voltage divider using a series of
high resistance resistors.
As almost any small transformer could be used, I think you should use a transformer
as it is safer.

while winding the coil of the servo stabilizer,wound the power supply at once so that any effect of voltage change in the transformer will through the winding affect the voltage output to your control
circuit.

thnks....But i want linearity in resolution of 1v... & want cost effective project...that's why i think to go with resistor network...which type of resistor i can use?...............
i am also attaching here just demo ckt for voltage down using resistor divider network..just check it