big L

There some pretty big ones in the nearby substation but I can't get near enough to read the rating plates.

They probably wouldn't state the inductance.

One outfit that makes utility transformer test sets say that their gadgets measure up to 10H. I was hoping to find something outrageous.

Hammond makes a 200H inductor. It is NOT good for 30 amps!

The superconducting magnets used in MRI machines have a very high inductance. I have seen values between 50 and 100H quoted.

John

I have seen test bridges with scales going up to 1kH - the highest value I have personally encountered was ca 150H

Someone's still building choke-loaded audio stages I guess. Them newfangled CCS just aren't trustworthy

I think the Fermi Lab's Tevatron magnet at 1000H and 1500A is one of the largest ever made but some of the latest GW class mains substation transformers must have similar levels of inductance and stored energy.

See:

That's cool.

I guess an old neon sign transformer could have a huge inductance, ballpark 1000 Henries maybe, assuming that leakage inductance is the main current limiter.

I had a giant one when I was a kid, 15 KV with insulators on both ends. The Jacobs Ladder arc must have been almost a foot long. Wish I still had it.

I'm designing inducor sumulators and am curious about how big real inductors ever get. My buddies at a big aerospace test outfit say they don't see anything above 2 H.

Inductors are the worst parts that we can buy. I can wave off the imperfections in my inductor simulators by noting how bad real inductors are.

Transformers don't store energy - large L has no particular benefit in their design, save limiting magnetizing current to below a certain acceptable level.

High L in audio is to reproduce lower frequencies with lower distortion.

RL

The SAFT/Alcatel plant in Scarborough used to have largish inductors for loading. Air-cored - ~10ft on a side.

Your watch would stop, if you were too close.

Large L ? Who needs it?

RL

Just found one in my junk box: 50H at 80mA. I thought initially it was a HV tranformer for valve (sorry - toob use) but no, it's a choke. I wonder what it would have been used for....

Trying to squish everything into a very small package must be murder on the Q.

In the olde days we used to have audio output transformers for impedance matching purposes, but modern amps don't seem to need 'em.

That's debatable.

An isolated flyback power supply transfers all its power via energy stored in the transformer.

And long ago tubes were expensive so it made sense to get voltage gain from interstage transformers.

Indeed. And that's just one aspect of it. The designers in the early stage of toob development deserve huge respect for the performance they were able to wring out of a single stage - and all just to save the hard-pressed consumer back in the day a few sheckles.

Have a look at:

One trick I've seen mentioned in a couple of books, was to use a single tube section as an amplifier for two entirely different stages of a radio or TV receiver. The tube's grid was fed a combination of an incoming IF signal, and audio output from the detector; the output at the anode was fed to both the detector input, and to the audio output (or a second, power-amplifier stage). Since the frequencies were so greatly different it was possible to use not-too-awful filters to combine and separate them, and they didn't interfere with one another badly enough to keep the system from working.

Quite a different era from today, when they're talking about single chips containing a trillion active devices!