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For those like me that like to ponder the imponderable, and try to unscrew the inscrutable, here are a couple of questions to, well, ...ponder;
What would happen if you put a v4 lf driver board into a v9 or v10 control board?
Or the other way, v9 lf driver into a v8,7, or even a v3.6a control board?
What would happen if you paralleled the primaries of two identical transformers, but left the secondaries (outputs) separate and fed them to independent loads?
What would happen if you added mosfets into the empty spots on mosboards that only come with 3 or 4 fets?
Some powerjacks come with every primary transformer wire taken one turn through a ferrite core. Some only do some of the wires. What would happen if you added a turn around a ferrite core to each wire that didn't come with one?
Some pjs come with large ferrite cores and others come with much smaller cores. How much does size matter?
If you can answer any of these, feel free. Or maybe you have your own "What would happen" questions to add....
What would happen if you put a v4 lf driver board into a v9 or v10 control board?
If you adjusted for the different connectors, it'd work perfectly. A v9 PJ LF driver is electrically identical to a v4 PJ LF driver. So much for progress.......
Or the other way, v9 lf driver into a v8,7, or even a v3.6a control board?
Ditto. You'd have to change the connector pinout/layout, but the circuit's the same...at least back to 4.0. (That's the oldest board I have.)
What would happen if you paralleled the primaries of two identical transformers, but left the secondaries (outputs) separate and fed them to independent loads?
Whichever transformer secondary went to the control board would have a regulated output...the output voltage of the other one would sag proportionally under loads based on the core and wire losses.
What would happen if you added mosfets into the empty spots on mosboards that only come with 3 or 4 fets?
Absolutely nothing. You'll have to add the gate resistors for the FETs to get the signals 🤣. Beyond that...really not much.
Some powerjacks come with every primary transformer wire taken one turn through a ferrite core. Some only do some of the wires. What would happen if you added a turn around a ferrite core to each wire that didn't come with one?
Every PJ I've seen (all single-transformer, mind you) has had 1 ferrite core on one transformer primary wire. Most of them have just a single turn...and if you put a 2nd turn around the ferrite, you can significantly reduce the no-load current of the inverter. This ferrite serves as a filter for the high frequency SPWM output of the MOS boards; beyond the "perfect absorption" of the SPWM hash, you're wasting your time. I haven't found any significant advantage between 2 turns around a single ferrite...and 2 turns around 4 ferrites stacked and glued together. Or 2 turns each around a ferrite on each transformer primary wires. Just adds cost and weight after a certain point.
Some pjs come with large ferrite cores and others come with much smaller cores. How much does size matter?
Similar to the above: beyond a certain amount, adding more ferrite does not help no-load current at all. Methinks the ferrite size is sorta determined by the size of the transformer wires--i.e. the big wires on big transformers can't easily be looped through a ferrite core.