Quote:
Originally Posted by Keith
..... rather than the beautiful original layers which I cannot hope to replicate.
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Back in the late 1970's I required to replace a layer wound line blocking oscillator in a TV which used an MW31-74 CRT. It had a fairly thin stack of iron laminations (many American line blocking osc transformers had ferrite cores even from the late 1940s).
In any case, it was important that not only the inductance was correct, but the winding self capacitance so that the self resonance and flyback time would be unchanged. At that point I didn't twig to the fact that I could have just jumble wound it for the correct number of turns and added external capacitance. So I was hell bent on having it layer wound, with the same geometry paper and the same wire & layers.
I visited a local transformer crowd and pleaded with them to layer wind it. (They thought I was a lunatic). In any case I persuaded them to do it and to my astonishment they perfectly layer wound it, no cheeks on the bobbin, with fine layers of paper. But it cost a small fortune. Even then the company manager remarked "I haven't seen a transformer wound like this in years what a masterpiece". I still have it somewhere.
With a frame blocking osc transformer the self winding capacitances are rarely an issue, more often too low than high and external capacity is easily added if required to get the correct flyback time.
As far as I am aware, there is only one common type of "transformer" still perfectly wound with layers and fine wire and this is the standard auto oil filled ignition coil, otherwise this technique has all but vanished.