REDD.47 a few questions.

[vmanj]

I with pleasure and gratitude want to learn wisdom from those who can share it with her.

This is not my formula, I saw it on the Internet, as a conditional approximation of the transformation ratio of INPUT and not output transformers.
With output transformers this does not work, I tested it with different examples.

I have produced my examples, where it works conditionally, is not it?
But is it going to be something terrible and terrible if I ask you to show an example of what this does not work and I'm mistaken ??

 

[ruffrecords]

But is it going to be something terrible and terrible if I ask you to show an example of what this does not work and I'm mistaken ??

Someone just did. To be honest  I am not sure what the issue is here. The method is clearly approximate. If you are building tube mic pres then you must have a signal generator and a means of measuring levels (DMM or oscilloscope). With these tools you can make an accurate measurement of the actual turns ratio. Why use a known flawed method when you can make a proper measurement?

Cheers

Ian

 

[ruffrecords]

Here is an example where the formula does not work:

http://www.lundahl.se/wp-content/uploads/datasheets/1952.pdf

For the 1:4 windings the dcr method gives 1:5.5

Cheers

Ian

 

[vmanj]

Well, yes, everything is correct.
So it was written that this formula does not give an accurate calculation, only an approximate representation.
It is more a toy and for serious tasks it does not approach.  :-[

 

[BoBoSan]

Hi Ian
Do you have any recommendations for a good high voltage psu that can run two REDD47 preamps
I have finished the preamp build and it works quite well but i have some concerns about psu
Thank you