I have moved this to here as I realised it was in the wrong place.
I was sitting watching the TV last night and this idea came to me as I said in the posting above to use duplication of some of the components so that you have more than one waveform hitting the cell out of phase with each other.
Also some people seem to think the choke in the negative is not so important.
Anyway here is a doodle I have put together this afternoon, I thought maybe try pulsing the positive instead of the negative all the time so maybe a P-channel FET.
I also had a look at DOG's posting about the inhibiting resistor.
"Electron Inhibiting resistor is simply any resistance that stops the flow to ground (As I understand it). I have used resistance values from 10 Mega Ohms to 1 Ohm. Simply stated, as you increase resistance on the negative side of the tube, the voltage across the tube increases. Of course, this only works when you have the blocking diode and choke on the positive side (driven by a transformer). "(http://propaholics.wolfchasers.com/uploader/users/oddball/ODDBALL%20PWM%20system1.jpg)
You could have both of the 555 oscillators with the same frequency components and just set one at a harmonic of the other it could be worth an experiment just add a 6 position switch instead of the 3.
I have just guessed at the biasing resistors and used what Lawton had but adapted the set up for P-channel, the problem is to turn a P channel on may take a negative voltage I don't know if just 0V potential will turn it on.
As you can change the mark space ratio on the Lawton 555 set up there should be no problem there.
As to the chokes maybe keep them separate and not bifilar at all.
EDIT0 Volts will turn on the P channel FET so have ordered some for a play with.
Also when I used to make H-Bridge drivers I always used a 10K resistor to stop a FET from switching to an indeterminate state so have changed the 2 x 820R resistors that Lawton had to 10K, and many of the DATA SHEETS say feed these FET’s direct
From an IC so I have also removed the 220R from the 555 pin 3 to the FET gate.
See H-Bridge motor driver with N & P channel FET's
http://www.cadvision.com/blanchas/hexfet/images/h-bridge.gifMaybe switching the supply ON and OFF on the positive side of the cell/capacitor and via 2 separate feeds and oscillators will give that voltage spike on the waveform you are after.
(http://ionizationx.com/index.php?action=dlattach;topic=97.0;attach=190;image)
Anyway this afternoon I got my scope out and an old NAND gate oscillator I made for an other project a few years ago.
So hooked it up to the cell to see what it gave me, and here is the waveform.
It is just pulsing the 12v as does the lawton but only 1 oscillator.
(http://propaholics.wolfchasers.com/uploader/users/oddball/waveform1.jpg)
It got me thinking the top part of your square wave has a ripple but it is only a slight ripple maybe a few volts compared to the 13.8 V or what ever you get from you rectified 3 phase.
So that means that this ripple frequency depends of the revs of the alternator and in turn the engine. The only constant thing is the square wave you are creating out of this rectified voltage, and that is different for each cell design am I right?
So this means that the lawton CCT fails because it still pulses the whole voltage during the top of the square wave.
So the idea I have above could be modified so the 2 waves are in sink but applied to each other at different voltages after being switched by separate FET's as I said.
So this means that both waves still need to be in sync to work.