Resonance or no resonance?

[gazzzwp]

I have been working with a stainless tube set up powered by a Dave Lawton PWM DC switching circuit.  My tubes may not be fully conditioned since they are still producing light brown scum experienced by others.

I have not yet managed to hit the resonant frequency, despite sweeping the frequency and trying various combinations of frequency and mark/space ratio.  I am using a quality oscilloscope.

I read on another forum that resonance is only possible using AC, and not switched DC.  Can anyone please confirm if they have managed to create a voltage spike from a resonant effect using switched DC?

I would like to know if it is possible, or have people been mistaking the resonant effect for some other phenomena?

Gazza

[Magnethos]

Ok, the first thing that you must to do if you don?t want to get a brown scum is to use a MAGNETIC stainless steel. Using magnetic material you won?t get any ugly byproducts.
You can see what I mean in a video on youtube:
http://www.youtube.com/watch?v=KO-U7nN8CsQ
In the video the guy compare 2 electrolysis system and he doesn?t get any brown or yellow scum in the water that is electrolysed with the Magnetic Steel. This is the first answer.

I?m not an expert in electronics, but I think the only way to resonate something is using AC. DC is always the same, it has not Cycles... all that has a resonance has a cycle, so you must to use AC instead of DC.

There is another DC called Pulsed DC, that I think that is a mix between AC and DC. I think that all you have read is about PDC and not DC.

If you want to get an efficient electrolysis system I read a lot of times that you must to use a High Frequency instead of a low frequency. Now, I?m studying a new system of a possible ultra-efficient electrolysis method. I will post more info here.

I repeat that I?m not an expert.

[TinselKoala]

Of course it is possible to induce a resonance with pulsed DC. However, whatever it is you are "ringing" will respond in an "AC" manner. Pulsed DC pulses go from say, 0 volts to 12 volts then back to zero. AC pulses of the same frequency, duty cycle and total RMS voltage would go from -6 volts thru zero to +6 volts. "DC offset" means something like -3 volts to +9 volts ( a +3 volt DC offset of an AC signal).
The response of the stimulated system will usually be some displacement (or voltage) that oscillates around zero, perhaps with some offset.

[TinselKoala]

I made a video illustrating some resonance phenomena in a piezoelectric element. In the specific case of pulse-driven water electrolysis, I have not been able to generate resonances in my electrolysis cells, but I have only just begun trying.
Usually at a resonance, there is considerable power transfer between the resonating system and its driver. Power may be reflected back along the transmission line into the source. When using a 'scope to monitor both the driving signal and the response of the system, resonance will generally be indicated as in the video below. Careful observation of only the driving trace, will often reveal the power transfer at resonance, because the amplitude of the driving trace will drop while the driven response amplitude goes up. So if you only have the driver signal, like in most water electrolysis experiments, you still may be able to tell.
If the resonance is mechanical in the cell electrodes, a shaking if you will, it may be possible to monitor that and detect Puharich or Meyer style acoustic resonances with a piezoelectric transducer like that shown in the video.
They are cheap.

http://www.mediafire.com/?ilznj3tqzyo

(about 34 mb)

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I have been working with a stainless tube set up powered by a Dave Lawton PWM DC switching circuit.  My tubes may not be fully conditioned since they are still producing light brown scum experienced by others.

I have not yet managed to hit the resonant frequency, despite sweeping the frequency and trying various combinations of frequency and mark/space ratio.  I am using a quality oscilloscope.

I read on another forum that resonance is only possible using AC, and not switched DC.  Can anyone please confirm if they have managed to create a voltage spike from a resonant effect using switched DC?

I would like to know if it is possible, or have people been mistaking the resonant effect for some other phenomena?

Gazza

TinselKoal is right. You can get something to reonante with pulsed dc. You have to be sure you have a resonant circuit though. Look up L/C resonance series and paralell. If you have a way to measure the capacitance of your WFC you can build a choke to the value that you need. Look up  L/C resonance calculator and you can plug the values in there to tell you what you need for l c or frequency.