Electron Reversing Device

[poynt99]

Conrad,

tinman is using his scope for these last measurements, pretty much as I have shown in the simulation. He is measuring the voltage across the 1 Ohm current-sensing resistors with his oscilloscope, so in effect he is showing the current in each leg. I have done the same.

tinman's measurements aren't too far off, but the interpretation of them may be. I also noticed that his magnetized screw driver used as a pointing device skews the scope display at least once in the video (around 4:25), so that should be something all should be aware of. I would also encourage him, and everyone to calibrate their scope probes prior to measuring, as an uncalibrated probe can lead to sloped tops on square waves.

[MileHigh]

Excellent work like usual Poynt.  Imagine giving your computer twenty minutes to crunch out a waveform by lowering the step size and increasing the precision?  It would be awesome.  I still reference computing power relative to the early Eighties in my mind.

Can't you just edit the model for a diode and change the IV transfer curve so it resembles a LED?  Just "stretch the voltage scale?"  I am assuming there is a real exponential-type transfer curve for a diode in the model?

It sure beats giving a stack of punched cards to the computing center and then going and picking up your output the next day.

MileHigh

[TinselKoala]

Well... I've been away on other things, but I see lots of progress is happening. I don't really think that there is much I can add except to say how happy I am that the sim results and .99's scopeshot analysis agree with my scope measurements mostly. The sim even captured the slight asymmetry between the positive and negative traces, where the slope isn't a perfect mirror image on the bottom. (This asymmetry was what I thought might be influencing the DMM results).

I've been meaning to comment for some time on this: Tinman, I think your scope might have a stable "false triggering" mode where it will display essentially two different timebase sweeps overlaid. I think I've seen this happening a couple of times in your vids, I'll try to duplicate it on my kit to demonstrate what I mean. Like if you have a complex signal that consists of a regular train of a few square pulses, then a long inductive ringdown, and repeating, your scope might trigger one sweep on the pulse train and the next sweep on the ringdown, hence overlaying the two images on the screen. And frustrating the heck out of the user; I see it a lot on my old HP180 when it's not yet warmed up properly.

But I'm crushed.... MH said,

Have you ever seen someone do a clip where they try to compare a BPC versus a regular coil to look for differences between the two?  I have never seen one myself.

http://www.youtube.com/watch?v=mvb39SwTXBE

[tinman]

@Poynt99
I never ment to insinuate that you made any reference to the BPC being the same as any inductor-im sorry if you took it that way.My questions were cincere.
And in reguards to me not responding to a few of your post,i do appologise-but as you know, i have been a bit busy elsewhere aswell as running my own forum.

So in reguards to your test and the time you have taken toward this circuit and explaining what is happening,i am happy with the outcome.
I have gone as far as i can with the equipment i have,and will have to wait until i can get a better scope and SG.
Thanks for all your input on this.

@ TK
It is good to see you back-long break for you.
I would be interested in knowing a bit more about what you think the scope may be doing,this could come in handy a little later on.
An yes-i to am a bit supprised at MH comment aswell,as there are many video's and lots of information about the differences in the BPC and a normal inductor or coil.

[MileHigh]

As I mentioned about modelling inductors, there is a university Wiki page called "Spiral Inductor Design:"

http://bmf.ece.queensu.ca/mediawiki/index.php/Spiral_Inductor_Design

Note the model that the person is using for a spiral inductor in the attached image.  There are stray capacitance and resistance components that come into play.  They model the subtle secondary characteristics of a spiral inductor in this case.  Note the "Cp," the coupling capacitance that bypasses the inductance alltogether.

So if you do something like look at how the coil responds to square wave you can observe the L/R time constant and that shows you how the coil responds in the time domain.  Then if you put the coil in a test circuit and then sweep a sine wave through low to high frequencies you could observe how the coil responds in the frequency domain.  Then you relate that back to your complex model and get a clearer picture of what's going on with your coil.  Once you know how the coil responds in the frequency domain then you know how it will respond to any arbitrary waveform.

If you are using Spice to model how a very high frequency circuit operates then you use the more complex model.  You can also see from the Spice waveforms that they do include some of these secondary real-world properties for most components.  That's why you see the spikes and ring-downs in the simulation waveforms.

So for a lot of the fancy coil configurations people play with you can assume that they are variations of the kind of modeling you see in this example.  But BPCs and pancake coils and Rodin coils are fundamentally still all coils.

MileHigh