Hello Jules,

answers below

Quote Originally Posted by JulesP View Post
Ok so the HV pulse from the generator's FET Drain (which reverses polarity and goes HV+) will connect directly to Pos of the Capture Cap. Where do the LM741 and the H11D1 get their power supply from?
The collapsing current of the coils, when the supply is cut off, is a positive current that must flow to a negative terminal (of a capacitor, or of a battery).

Quote Originally Posted by JulesP View Post
The 12V build then is suitable for a 36V setup and perhaps the lower threshold might be set at 40V and the upper at 48V but the lower in particular might need tinkering. Is it R10 that adjusts the lower and R13 the upper? I appreciate what hysteresis means in magnetic terms but not sure in this context (the amount of lag between the charge and discharge?) To clarify these thresholds visually is the attached right and the cap would normally discharge at the lower threshold?
It seems to me that the roles of R10 and R13 are those. The simplest method of tuning I found was to tune the high and low thresholds by feeding the Cap Pulser with a DC lab supply and placing a voltmeter at the output of the mosfets. Place a resistive load at the output to drop the voltage when cutting the source.
I specify that I have never tried to set the threshold higher than 48 V, but 23 / 24V.
The term "hysteresis" can also be applied to a device that has a control of the level of the ignition voltage different from that of stop. This is the case, for example, of the thermostat of a refrigerator. In Cape Pulser, there is a hysteresis comparator.

Quote Originally Posted by JulesP View Post
My small batteries are 7Ah each so three in series would happily be met with just one of those 15000uf caps?
A single capacitor 15000uf would suffice for 3 X 7 Ah.

cordially
mml