Lenzless resonant transformer

[itsu]

Test done by itsu, testing resonance effect in a toroid using two similar overlapped coils. Differs from my tests where coils were separate and on opposite sides of the toroid. But an interesting test result still.

Ok, i can now work on some suggested changes, like using prim./sec.  on opposite sides of the toroid.
But first i will try some more measurements suggested by verpies like testing resonance with secondary open or bulb only.
And to rewind my coil to be forth and back around the core instead of twice around it as it is now.

Regards Itsu

[verpies]

Test done by itsu, testing resonance effect in a toroid using two similar overlapped coils. Differs from my tests where coils were separate and on opposite sides of the toroid. But an interesting test result still.

Do you realize that by making the coils narrow and separate and winding them on opposite sides of the toroid you decrease the coefficient of magnetic coupling and increase flux leakage?  This significantly decreases the energy transfer efficiency in such transformer.

[Jack Noskills]

Magnetic current wants to loop back to itself through every possible route it can, even through air. Air has permeability of 1, my core has 80000. It is my opinion that this looping occurs according to path reluctance, so in my case only 1/80000 part would go through air so this leakage will be insignificant here.


But, purpose here is just to check how resonance effect changes by using two coils on opposite sides. I should have tested this myself but I forgot, so my bad. In my testing using two separate coils I had just one resonance point (primary lamp off while brightly secondary lit), but maybe my rude measurement style just did not notice it. My input bulb was 5 watt and output 10 watt halogen. Normal trafo operation would be that input bulb always has more light than output right ?


If I would use small capacitor in place of bulb then that should give me maximum input power system can use at a certain frequency ? How to compute that, Q*U*U*2*frequency ?

[itsu]

My input bulb was 5 watt and output 10 watt halogen. Normal trafo operation would be that input bulb always has more light than output right ?

Well, remember that the input bulb is "outside" the primary (parallel) LC, while the output bulb is inside the (serial) LC, so i doubt
that "Normal trafo operation" applies on the brightness of these bulbs.

The second question i leave for more knowledeable people 

Regards Itsu

[verpies]

Magnetic current wants to loop back to itself through every possible route it can, even through air. Air has permeability of 1, my core has 80000.

That is almost true.  The cs.area and length of the magnetic path are also factors.

It is my opinion that this looping occurs according to path reluctance, so in my case only 1/80000 part would go through air so this leakage will be insignificant here.

80000 relative permeability is a lot for a ferrite core, but it is achievable with Metglas and Nanoperm materials.
However, 80000 relative permeability does not mean 80000 lower reluctance than air when core shape/length and its crossection are accounted for.
But, yes most of the flux will be confined to the core of such high permeability.

But, purpose here is just to check how resonance effect changes by using two coils on opposite sides.

Large current flowing in the secondary winding will expel flux from under it, even if the permeability of the core is 80000.
Sufficiently large secondary current will make that core segment appear as if it had the permeability close to air.
This effect is not minor like the previous one.

Also, when the high permeability core saturates at 1A and 100 turns, then its differential permeability will fall down to almost 1 and it will create a lot of transfer nonlinearities before that.

It makes no sense to invest in a core with 80000 permeability only to decrease the magnetic coupling coefficient of a transformer built upon this core by pri/sec winding separation.
If you want to have small magnetic coupling coefficient in a transformer, you might as well build it around a low permeability core or an air gapped core (both will not saturate so easily and will be more linear).

Normal trafo operation would be that input bulb always has more light than output bulb, right ?

No, because the input bulb indicates the input current and the output bulb indicates output power.

Well, remember that the input bulb is "outside" the primary (parallel) LC, while the output bulb is inside the (serial) LC, so i doubt that "Normal trafo operation" applies on the brightness of these bulbs.

That's true, too.

If I would use small capacitor in place of bulb ...

Which bulb?