On Wed, Dec 25, 2024 at 02:39 PM, Bell, Dave wrote:
The boost/buck question depends completely upon the taps of TR1.
I believe there were 5 taps in the drawing, labelled A … E.
If C was defined to be the 220VAC (Phase) input, then there would be two boost taps (D, E) and two buck (A, B).
Almost, but not quite. One of the pins is the common, leaving you with 4 pins for choosing the input:output transformation.
A is the common. The input voltage may be applied between pin A and:
- pin B, leaving you with C, D, and E as "boosted" output voltages;
- pin C, leaving you with unused B, or D and E as "boosted" outputs;
- pin E, leaving you with only D as a "buck" output (other pins unused).
There is also the straight-through one where input flows to output without passing "through" the transformer (but is also applied between pins A and E so that other circuits receive power).
So you get one straight-through, plus potentially five "boosted" outputs, and one "buck" output. I don't know if all seven combinations are selectable but those are the potential ones. On top of that, the right half of the schematic disconnects the output, presumably for under/over voltage conditions that can't be corrected.
Andy
