Dual capacitor paradox

[captainpecan]

I have been interested in doing more work on this part of things for a long time and decided I wanted to learn more about it. The dual capacitor paradox has always been something that I didn't really understand well, but feel there is more to it and that maybe if we can get the efficiency up, it would be a wonderful way to run pulse motors or other oscillator projects.


For those unfamiliar, the two capacitor paradox is when you take 2 capacitors, 1 charged up and the other one is empty. If you hook them in parallel with each other, the energy flows from 1 into the other until the voltages balance out between the two. This gives the illusion of the energy being split between the two caps. That is not in fact the case. You actually lose about 1/2 the energy in the system when the voltages split between the two. I am not disputing that the energy is lost. That is proven and very repeatable on the bench. I am studying the why behind it, and trying to understand for sure where it went and see if we can find an efficient way to conserve it.


There have been many working on this problem, and there are some really positive results. Some work that Russ showed in one of his videos was superb and my inspiration to get back to working on this problem. The following video is 1 of 15 I think that he made in a series to answer some huge questions. They are all well worth watching every second. This particular one deals with this subject, video 5. It is a long video, and he explains things very very well, but to skip to the nitty gritty part for those who are familiar with all of this, move to about 30 minutes to see him setting up the effect I am looking for and 34 to see him send almost all energy from 1 cap right into the other and catch almost all of it.
https://youtu.be/Iw1FSr6xWek


I have been working with this and so far I have been able to replicate it, but only using very small capacitance. So small, that there isn't much I can do with it to be honest. That is what I am researching in this thread. Possible ways to build on what he has done. I will be adding to this thread as I do more experiments. I am working on several different things relating to this concept, but the overall reason for this thread is inspired from Russ's work.

[captainpecan]

I have also been working on trying to use a little hack I found that can supposedly charge a capacitor much more efficiently. It does help understanding principles that may be able to be adapted for use in the two capacitor setup. This hack is for charging capacitors from a stable power source, and I have no idea how he actually figuring his efficiency but the entire thing is worth noting and very cheap to replicate. I ordered 10 of these circuits for about $10 to experiment with in various ways.
https://hackaday.io/project/28432-coin-cell-jump-starter/log/72237-how-to-charge-a-capacitor-efficiently


I first modified one, and forgot to solder a wire. I hooked it between 2 capacitors and smoked it immediately.... 1 down...


I then realized my stupid mistake, and got the 2nd one exactly correct. I hooked it up between 2 capacitors and smoked it immediately as well.... 2 down.


I then decided the resistance must need to be increased between the first cap and the circuit so I can slow down that current to manageable levels and make adjustments as I go and check efficiencies. I put a 5k potentiometer in line with it. It then worked, but it was discharging very slowly as the 2nd capacitor was charging slowly. It still just balanced out the voltages and did not send most of the voltage from 1 to the 2nd. And when I tested the efficiency, it was only 38% efficient. Just discharging the 2 between themselves was getting me about 55% efficiency.
I then adjusted the pot down to about 300 ohm and did it again. The pot immediately glowed red and smoked.... lol... 1 pot down as well now... I think the next test will be with physical resistors instead of potentiometers. I believe the pot roasted because it is actually very fine wire inside it.


Nothing great learned from this experiment yet except for how to fry some stuff! Now I know a little more about what NOT to do.

[captainpecan]

As far as following Russ's work. I am trying to understand properly choosing capacitance with the correct inductor. This appears to be related to tank circuit building, but my inexperience here is getting me confused. I measured the inductance of a coil I wish to use for my experiments and it is 120mH. All the equations I am finding relate things to frequency as well to match capacitors to inductors. I want to use it for 1 pulse from 1 cap, through the inductor, and landing into the 2nd cap. There really isn't a frequency. At this stage I am testing efficiency of each pulse for a possible use in pulse motor applications. Of course, it isn't enough to even be useful yet, but that is what I am working with and learning from. Does anyone have any more experience in this field of capacitors and inductors and matching them properly without actually having a frequency to work with? I do plan on moving solid state with this stuff so frequency of course would be very useful then, but for now, I am trying to understand it all and learn as I go. Just put my mental questions out there in case someone has stuff to ad.

[gyulasun]

Have you seen member poynt99's paper on capacitor energy transfer?  There was an Uploads part of this forum but now I cannot find any such icons on the left hand side column it used to be there....
So I attached the pdf file from my HD.

[ramset]

Sorry to interrupt
I also believe member OnePower was recently having some discussion on this topic
I am uncertain if exact capacitor experiment.?  However ...
Will try to drop a note to him!
Respectfully
Chet K
As always please remove for any reason!