Inductor coupling

It's difficult to take anybody seriously who doesn't know the transformer e quations

V1 = L1.dI1/dt + M. dI2/dt ( + I1.R1)

V2 = M. dI1/dt + L2. DI2/dt ( +I2.R2)

where L1 and L2 are the inductances of the two windings, I1 and I2 the curr ents through them, and M the mutual inductance between the two windings, wh ere

M = k. square root (L1.L2) where k - the coupling coefficient - is betwee n 0 and 1.

In reality, some current flows in parallel with I1 and I2 through the paral lel capacitances of the coils, and some of the voltage across the coils is generated by the current flowing through the resistance of the coils (R1 an d R2), but the transformer equations are where you ought to start analysing what's going on.

In the context of what he is doing, I don't see why he should, unless pomp was his intent. The applied stimuli and the measured results are voltages. Currents are never even mentioned.

I think this work was useful.

Jeroen Belleman

I've seen quite a bit of sloppy thinking straightened out by the transformer equation (some of it mine).

There's nothing pompous about getting the fundamentals right.

Except by implication - inductance is the ratio of the voltage generated to the rate of change of current through the device exhibiting the inductance.

You can't measure it without driving a current through the device

Of course. But it would have been more useful with a bit more introduction.

Providing a link to Wikipedia as whole, rather than - say - the Wikipedia entry on mutual inductance, does strike me as pompous. Not that

is as helpful as it might be.

is better (or at least looks better to me, after superficial inspection).

Good expositions aren't easy to find. I hope that AoE 3 does better than AoE 2 did - I put in an appeal to Winfield Hill for a better exposition of the subject when he was asking for potential improvements to AoE 2 a few years ago.

Slowman is in desperate need of attention, with the additional requirement to denigrate anyone in his path.

Jeroen, Why don't you do us all a favor and killfile Slowman, so we won't be exposed to his constant BS? ...Jim Thompson

Jim-out-of-touch-with-reality-Thompson gets it wrong again.

Not a request Jeroen is likely to take seriously - if he even sees it. Jim's off-topic BS can be hard to take. Why should we care if Jim's son-in-law finally made judge in Arizona - but Jim told us about it anyway.

And I don't denigrate Jim for that kind of error of judgement - just point out stuff that he's got wrong that people might otherwise take seriously.

Thanks for the link, Tim.