30-06-2018, 05:08 AM
"why can't you put tap on the eight and a half turn?" It don't work like that Terry, voltage is less or more only by complete turn, at least on toroid's. I spent ages mucking about with bits of turns to try and get wndgs bang on at first and would have thought that voltage changes along the length of a turn, it doesn't.
6.8v unloaded I should have said.
I've measured a few htr's wndgs on EI cores, they're pretty equal, on the whole. They have to be for hum cancellation no?
Tap was to be connected 100v or thereabouts to elevated htrs on cathode follower Lawrence, so maybe exact balance not essential, but . I was more interested in the question for future reference and curiosity . In this case I'll just use two 220r resistors to give a virtual tap.
Of coarse it's possible to get a tapped wndg exactly equal in resistance and voltage by using a twisted/bifilar wire, but I can't see tfmr makers doing this due to cost. I'll dig some tfmr's out and measure them this morning and report back.
Andy.
6.8v unloaded I should have said.
I've measured a few htr's wndgs on EI cores, they're pretty equal, on the whole. They have to be for hum cancellation no?
Tap was to be connected 100v or thereabouts to elevated htrs on cathode follower Lawrence, so maybe exact balance not essential, but . I was more interested in the question for future reference and curiosity . In this case I'll just use two 220r resistors to give a virtual tap.
Of coarse it's possible to get a tapped wndg exactly equal in resistance and voltage by using a twisted/bifilar wire, but I can't see tfmr makers doing this due to cost. I'll dig some tfmr's out and measure them this morning and report back.
Andy.
