On 4/29/23 2:45 PM, John Woodgate wrote:

That's the trouble. Vastly over-simplified articles like that, while not wrong, tell you just enough to get totally confused. For example, you set the turns ratio right, to get 6 V out from a 120 V input, but you set the inductance of the 120 V winding 3 to 6 orders of magnitude too low (or too high; then then transformer works but costs $1000 too much).

That is a design problem rather than a simulation problem.

?Looking at the sheet that came with some FT114-77 toroids I acquired a decade or three ago I see a formula for calculating the number of turns given a desired inductance. Which depends on a parameter that varies quite a bit depending on the particular core used. 1270mH/1000turns for this one.

The trick in designing a transformer is to make it large enough so that the core doesn't saturate. But not too much larger.