salvaged Arnold AH-7 c-cores?

[multi-volti]

I have a small pile (6-12?) of NOS inverter transformers from the late 70's. They use tape wound cut cores marked AH-7. Even if I could identify their use, they are still useless to me as-wound...but why discard them?

I unwound one today and am thinking about experiments with the cores.

Someone told me they were Arnold type 'A', thickness 'H' (0.004"), size '7'.

I haven't found a table for size 7 but they are easy enough to measure.

If I'm reading 'A' correctly, Mag-Inc material 'A' is Square Orthonol, 50% nickel, 50% iron. Square Orthonol which might not be a first choice for PP audio output transformers...but with an air gap, for a small SE output transformer, I think an experiment is in order.

Size 7 tells most people nothing... so, 1" wide tape, 3/8" 'stack', width of a pair about 2-3/8", the window formed by a pair is 1/2" x 1.5", overall core set footprint 1-1/4" x 2-3/8" x 1".

Thanks

 

[multi-volti]

Ok, not a stupid idea (offline opinion)...
They are 0.004” silicon steel, not square Orthonol. “I assume grain-oriented, but, hey, don’t be greedy, self”.

DEFG product = 0.285 in^4. MPL = 5.1”

I’ll assume years-ago Cerrem advice for 12-13 kGauss (AC & DC combined), will go weigh my cores & pick some more numbers.

Still looks like ‘small output transformer’ potential...how small TBD.

 

[PRR]

If they are "tape wound", the obvious assumption is that the tape is slit along the magnetic grain orientation.

I mean, you could slip barn-roof iron at random angles, but hardly supports the subsequent effort of C-coring, cutting and polishing and strapping.

That's small for a Champ. So I predict 2W-5W depending what you call "bass".

 

[multi-volti]

These are polished. They came from an inverter transformer and had only whatever micro-gap was present with the cut and polish. The core set is 1.25”x2.35” with 1” strip & a pair is 0.53 pound...’build-up’ is 0.38” - they seem substantial...just have to make

MagMet design catalog formula and a more educated transformer engineer both indicate about 20 VA as a 60 Hz power transformer. The latter estimated 10W as SE guitar output or 5 W for hifi.

I have to figure out a good winding plan with that geometry...
I have six sets, so of course a PP one beckons too.

I got rid of all my magnet wire except Litz because I was frustrated most of it wasn't solderable Poly-Nylon. In hindsight, that was dumb.

I have a quart of Dolph AC-43 varnish, or did many years ago...I might have a brick and all I really have is cores & ambition.

I am glad I didn’t toss the previously useless inverter transformers (Heathkit 54-202, IIRC).

I was trying to make space in the basement but I’m not doing well...toss one, keep six...

 

[multi-volti]

Opportunity to learn Google Sketchup and take .STL files to someone else who has a 3D printer. That's easier than finding bobbins or paper tubes (minimum order per line item).