Yes, the total 'series' inductance is the same.
Is it truly in series?
2000 turns actually in series, end to end.
Or, 1000 turns laid down beside 1000 turns.
The Inductance of 1000 turns from Cathode to ground is 1/4 the inductance of a 2000 turn primary.
And the Inductance of 1000 turns from Plate to B+ is 1/4 the inductance of a 2000 turn primary.
They are driven by 2X the current (plate delta current, plus cathode delta current).
Effectively, the bifilar windings are in parallel (side by side, driven by equal delta currents that are in phase as to the magnetizing of the laminations).
That is the same as soldering the two 1000 turn wires together at each end (beginning of 1000 turns together; and then at end of 1000 turns together), then applying 2X the delta current.
A single wire of 2X the cross section area, with 2X the delta current through the single wire will have exactly the same magnetizing effect on the core.
Just how I see it, correct or not.
I need to think about this some more.
OK.
Plate delta current driving 1/4 the inductance.
Cathode delta current driving 1/4 the inductance.
But those two delta currents are effectively in parallel, so plate delta current + cathode delta current driving 1000 turns, is effectively driving 1/2 the inductance of 2000 turns in series.
The two delta currents aid each other.
Is it truly in series?
2000 turns actually in series, end to end.
Or, 1000 turns laid down beside 1000 turns.
The Inductance of 1000 turns from Cathode to ground is 1/4 the inductance of a 2000 turn primary.
And the Inductance of 1000 turns from Plate to B+ is 1/4 the inductance of a 2000 turn primary.
They are driven by 2X the current (plate delta current, plus cathode delta current).
Effectively, the bifilar windings are in parallel (side by side, driven by equal delta currents that are in phase as to the magnetizing of the laminations).
That is the same as soldering the two 1000 turn wires together at each end (beginning of 1000 turns together; and then at end of 1000 turns together), then applying 2X the delta current.
A single wire of 2X the cross section area, with 2X the delta current through the single wire will have exactly the same magnetizing effect on the core.
Just how I see it, correct or not.
I need to think about this some more.
OK.
Plate delta current driving 1/4 the inductance.
Cathode delta current driving 1/4 the inductance.
But those two delta currents are effectively in parallel, so plate delta current + cathode delta current driving 1000 turns, is effectively driving 1/2 the inductance of 2000 turns in series.
The two delta currents aid each other.
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A single tube in a normal push-pull transformer is driving half of the total primary turns all in series (easy to visualize).
A single tube in a Unity-Coupled push-pull transformer is also driving half of the total primary turns all in series. A quarter are between cathode and GND and the other quarter are between plate and B+. Nevertheless, 50% of the windings are in series just like in the case of a normal push-pull transformer. The fact that the tube is in the middle vs at one end or the other (we could also consider a cathode follower push-pull amp with a normal push-pull transformer) doesn't make a difference as far as the inductance goes, does it? The primary inductance that a single tube will see will just be based on core and how many turns it is driving in series, however they are divided between cathode and anode loads.
I mean, I'm no transformer expert so correct me if I'm wrong, but that's how it seems to me.
A single tube in a Unity-Coupled push-pull transformer is also driving half of the total primary turns all in series. A quarter are between cathode and GND and the other quarter are between plate and B+. Nevertheless, 50% of the windings are in series just like in the case of a normal push-pull transformer. The fact that the tube is in the middle vs at one end or the other (we could also consider a cathode follower push-pull amp with a normal push-pull transformer) doesn't make a difference as far as the inductance goes, does it? The primary inductance that a single tube will see will just be based on core and how many turns it is driving in series, however they are divided between cathode and anode loads.
I mean, I'm no transformer expert so correct me if I'm wrong, but that's how it seems to me.
Yeah, thinking about impedances just gets us cross-eyed. Transformers are just transformers. They're magical V/I converters with parasitic reactances, some in shunt, like the magnetizing ("primary") inductance and the summed ("primary") capacitance, and some in series, like the lumped "leakage" inductance. Unless we're worrying about transformer behavior out where these parasitics become important, the poor (poor choice of word - maybe something like "incomplete" would be better) quality of this model doesn't even matter.
When we get back to volts and amps we stand on firmer ground. Abstractions like "impedance" fall out from that firmer ground, but aren't a true substitute.
All good fortune,
Chris
When we get back to volts and amps we stand on firmer ground. Abstractions like "impedance" fall out from that firmer ground, but aren't a true substitute.
All good fortune,
Chris
Yes, it's correct. Half the turns number inevitably means a quarter of the original inductance. But as it also means a quarter of the original impedance, how does it matter wrt the LF roll off?
Best regards!
Best regards!