Quote from: gyulasun on May 22, 2014, 05:09:07 PM
Thanks for testing it.  I think when the load resistor was 1 kOhm, the input current draw went up towards the 200 mA because of the normal  transformer operation (coils are on a common closed core).
If I saw correctly in the video, the core resonance occured around 17 kHz, right? 
Have you considered putting the transformer core onto a light, elastic material like a piece of sponge to support it, instead of the glass? I mean the mechanical amplitude at core resonance may get damped on the hard surface of glasstop, though the insulating tape you wrapped up the coils may help to avoid damping.

Gyula

The resonance does not occur @17 kHz per se. It is not a specific frequency that is important but a combination of frequencies to which a core is subjected.
The latest results (with a 1k load) showed that the resonance is so sensitive to frequencies that a 0.5Hz difference between frequencies was critical.

As far as the actual core is concerned, I prefer it like it is. I  am also studying the effect of the air gap on resonance and need the core easily accessible.

~A

The resonance that I am observing is very much like a MNR resonance except that I am not reading a electromagnetic radiation response from nuclei in magnetic field but rather a complex response from magnetic domains in initial magnetic field.

I am not quite ready to explain he effect in full but it is clear that a right combination can be found on different sets of frequencies.

Quote from: avalon on May 22, 2014, 06:23:37 PM
The resonance does not occur @17 kHz per se. It is not a specific frequency that is important but a combination of frequencies to which a core is subjected.
The latest results (with a 1k load) showed that the resonance is so sensitive to frequencies that a 0.5Hz difference between frequencies was critical.

As far as the actual core is concerned, I prefer it like it is. I  am also studying the effect of the air gap on resonance and need the core easily accessible.

~A

The resonance that I am observing is very much like a MNR resonance except that I am not reading a electromagnetic radiation response from nuclei in magnetic field but rather a complex response from magnetic domains in initial magnetic field.

I am not quite ready to explain he effect in full but it is clear that a right combination can be found on different sets of frequencies.

I feel that information is useful for the Dual TL494 people.

Это видео демонстрирует тот эффект что я использовал в фонарике.
This video demonstrates the effect that I used a flashlight.

http://www.youtube.com/watch?v=bdPgIQoFaq0

Quote from: semenihin-77 on May 23, 2014, 11:53:31 AM
Это видео демонстрирует тот эффект что я использовал в фонарике.
This video demonstrates the effect that I used a flashlight.

http://www.youtube.com/watch?v=bdPgIQoFaq0

One coil?
You mentioned that you scope is connected to the power line. Is it in line with the coil? Would you mind to show the schematics?
In any case, very peculiar indeed.

~A

How much power is your signal generator providing to the circuit?

You do know that the voltmeter on your power supply will read the voltage across the output terminals... regardless of whether the voltage is coming from the supply, or from the circuit, right?

So I think your PSU is set to provide the lower voltage, and when you have it hooked to the circuit, it's reading the higher voltage injected by the function generator, or stored in the capacitors. Or perhaps you have one of many different kinds of possible groundloops. Who really knows what is grounded to what, and what is connected together by the scope's ground leads and the PSU's negative output. In my laboratory, I know, and I can isolate the FG and the scope if necessary.


ETA: I have just confirmed this with my FG (Interstate F43) and my main PSU (Topward 6306D).  Hooking the output of the FG directly to the output of the PSU, Red FG output to positive, Black FG (shield, ground, isolated) to negative, PSU set to zero voltage output, FG set to produce positive square wave at 1000 Hz. The Digital Voltmeter on the PSU reads the voltage supplied by the FG, even though the PSU is set to make zero voltage of its own. When the PSU is cranked up to make some voltage (careful here!) the meter indicates the higher of the PSU's set voltage and the voltage output of the FG.