Confirming the Delayed Lenz Effect

[teslaalset]

Well, I think we have to consider how good the shorting effect is the LED(s) represents with respect to the effect of a real short like a piece of wire?

The green LED needs about 2V forward voltage and assuming a 15mA current for the brightness in Luc's video, this LED represents a loading resistor of 2V/0.015A=133 Ohm, very far from a short circuit case.

I am not sure this is true.
The shorting resistance will be  delta V_LED / delta I_LED in my view, looking at common diode I/U characteristics. Normally this is a quite steep curve.

Attached an example of a fairly common LED.
Going to the U/I curve the delta U/ Delta I is around 0.2/0.035 => approx. 6 Ohms

[woopy]

Hi all

Special thank's to Gotoluc for his experiment.

So i tried a replication and it seems to work very well.

I wonder if ,( as it has already been proposed by a user i don't remember the name sorry), we placed an amplificator (for example a HI FI ampli) between the signal generator and the Mot if we could increase the effect and test more power. What do you think ? Any idea Thane ?

Thank's to all for sharing this very interesting stuff.

Good luck at all

Laurent

http://www.youtube.com/watch?v=vt9tqQfYpmk

[gotoluc]

please don't forget that when you try to lower your frequency to the 60 Hz you mentioned that you will kill the desired Delayed Lenz effect at your secondary side. So as a result of this I would expect that you cannot run your load purely reactive again. Because if the only important thing to this was primary power factor correction related, than every manufacturer of microwave oven transformers would be doing this.

Hi Overunityguide,

I was also thinking like you on lowering the Frequency would eventually null the effect. However, last night I paralleled all the AC Capacitors I have available on my boat and it makes a 37.4uF value.

Using this value I was able to drop the Frequency down to 250Hz and to my surprise the effect is still there and the bonus is the Secondary is now delivering about twice the Current at this lower Frequency. I connected 2 LED's in Parallel and each are in Reverse polarity to each other so both sides of the Sine Wave gets Shorted.

Below are the scope shots:

First Shot is @ 250Hz no Load on Secondary and no Capacitor on Primary (idle transformer)

Second Shot is @ 250Hz with Dual LED as Load and 37.4uf Capacitor on Primary

Later today I will get my larger AC Capacitors out from the storage to further drop the Frequency.

Stay tuned

Luc

[gotoluc]

I guess it is a single LED, so, indeed it kind of shorts one half of the cycle.
Because it's shown in resonance, it doesn't show a clear distorted current waveshape (a not symmetric sinus).
Would be interesting to see what happens if there are 2 anti-parallel connected LED's are applied, so both sinus halves periods are performing shorting.
I would expect a more explicit phase shift in that case.

Hi teslaalset,

I thought of doing this last night so there is now 2 anti-parallel connected LED's.

Results are the same and since I dropped the Frequency down to 250Hz the current is double so both LED's are fully lit.

Luc

[gyulasun]

I am not sure this is true.
The shorting resistance will be  delta V_LED / delta I_LED in my view, looking at common diode I/U characteristics. Normally this is a quite steep curve.

Attached an example of a fairly common LED.
Going to the U/I curve the delta U/ Delta I is around 0.2/0.035 => approx. 6 Ohms

hi teslaalset,

Yes, you are correct in that I should have considered dynamic resistance for the LED just like it were a Zener diode and I agree that the loading effect corresponds to a non-linearly changing resistor with an average r=6 Ohm value in the case you picked from the data sheet graph.
But still I think we should not omit the fact that the AC sine wave amplitude coming from the secondary cannot drive any current through the LED whenever the instanteneus voltage amplitude is lower than or opposite to the forward voltage of the LED.  So considering one AC cycle and only one LED  (Luc used only one), the loading effect from a LED comes as a resistor-change from a few Ohms to a near open circuit during a certain part within one half cycle of a full cycle.  In case of two anti-parallel LEDs the loading effect widens with a certain part within the other half cycle and thus current cannot flow at and near to the zero crossings till the voltage amplitude reaches near  +/- 2V or whatever the forward bias need for the LEDs.

And even with as small dynamic resistance as a LED may manifest you still have to consider the microwave transformer secondary coil copper resistance in Luc's setup as being much higher than the 6 Ohm, so the ruling effective resistance to consider for phase shifting when talking about shorts is that of the secondary coil, having a 80-100 Ohm DC resistance for a oven transformer secondary.

rgds,  Gyula