Confirming the Delayed Lenz Effect

[gyulasun]

Hi Luc,

Would like to comment a few things. 

It can be controlled by the AC Frequency sent to the Primary. A higher Frequency will Increase the Primary Impedance even more but it will also start Lowering the Secondary's Current Output Efficiency. So I tuned to have closest to a zero effect on the Primary so the Secondary can stays efficient. 

I think this behavior comes from the MOT core laminations poor performance at the increasing frequencies. When you have time you may wish to replace the MOT with the ferrite core having the 7.5H inductance and repeat this test.

On your scope shots above:  green trace has 20V/DIV and the square waveform has 3 vertical heights above the zero line and about 2.1 vertical heights downwards, this gives 5.1 x 20V= 102V peak to peak and the scope displays 208V peak to peak, about twice as many? 
The same goes for the yellow trace, it is set to 1kV/DIV and the peak to peak is about 3 up and 2 down again, giving 5kV peak to peak, yet it displays 9.97kV, about twice as many again.  This is not a problem now of course, just I noticed... lol

However, when you have to measure some kV amplitudes, then the normal scope probes may not have the correct ratings, having only 600-700V specification,  so these can easily get damaged from the 4-5kV unloaded tests. There are of course HV probe types manufactured for the some kV range but those are more expensive too.

IT is good you have tested this delayed Lenz effect and hopefully with the better toroidal core quality you can find it again and get higher output power (with the MOT, core loss and secondary coil copper resistance are rather high and limiting factors).

Gyula

[plengo]

Excellent work Gotluc.

Can you publish the schematic of your H-bridge?

I would like to replicate your work. I do have a MOT and I can build the bridge too.

Thanks,

Fausto.

[gotoluc]

When you have time you may wish to replace the MOT with the ferrite core having the 7.5H inductance and repeat this test.

Hi Gyula,

I did make a Primary on the 7.5H Ferrite Toroid and tested it. I posted the results back on page 15 on the bottom of a reply to you:  http://www.overunity.com/index.php?topic=11350.msg301782#msg301782

Anyways, it does only normal transformer action. Maybe the effect has somthing to do with the Steel laminations?

On your scope shots above:  green trace has 20V/DIV and the square waveform has 3 vertical heights above the zero line and about 2.1 vertical heights downwards, this gives 5.1 x 20V= 102V peak to peak and the scope displays 208V peak to peak, about twice as many? 
The same goes for the yellow trace, it is set to 1kV/DIV and the peak to peak is about 3 up and 2 down again, giving 5kV peak to peak, yet it displays 9.97kV, about twice as many again.  This is not a problem now of course, just I noticed... lol

I noticed that also. I'll see if they maybe have a newer version of the Software

However, when you have to measure some kV amplitudes, then the normal scope probes may not have the correct ratings, having only 600-700V specification,  so these can easily get damaged from the 4-5kV unloaded tests. There are of course HV probe types manufactured for the some kV range but those are more expensive too.

I do have an expensive High Voltage probe on Channel 2. That's why it's set at x100

Can you have a look at the above Scope Shots as I would like your comments.
Notice on the first Shot how each 50% duty Phases of the H-Bridge to the Primary seem to only effect the Secondary at the beginning of each Phase change. The Secondary seems to have a ringdown like if the rest of the of the on time of the Primary is wasted. Notice on the second Shot (Secondary on load) the voltage on the load drop again like if most of the 50% phase on time is not doing anything to hold the current on the load.

Am I not reading understanding this correctly?

Thanks for your time

Luc

[gotoluc]

Excellent work Gotluc.

Can you publish the schematic of your H-bridge?

I would like to replicate your work. I do have a MOT and I can build the bridge too.

Thanks,

Fausto.

Hi Fausto,

I'm going to be building a new design of H-Bridge that I can adjust the duty cycle since I'm starting to think there maybe wasted current on the fixed 50% duty cycle.
So you may want to wait a week or two and see how my next build will work out.
I don't have a Schematic for my next build yet, it's just going around in my mind at this time. However, I do have some components on delivery.

But if you want to build the one I have which was designed by Groundloop to use components I had on hand (see below) feel free to do so.

Luc

Here is a link for 5 of the IR2103 for $10 delivered: http://www.ebay.com/itm/5pcs-IR2103-DIP-IC-NEW-/190481621070?pt=LH_DefaultDomain_0&hash=item2c5996e04e

[futuristic]

If one would use you circuit and hook it up to a signal generator (with variable duty cycle) then no change to circuit is necessary to have a variable duty cycle in output AC signal?
Or am I wrong?

Thank you,
Frenky

EDIT:
I see that the first chip is flipflop so I guess it wouldn't work...