Tentative TC design: first considerations
These are just the first steps before writing a formal specification of my
TCs to be built.
In my understanding the AC xfrms used to feed most of built TCs are just an
extra sort a complication for its modeling. My TC uses actually "pulsed DC"
from its tank supply: that is, the tank provides a voltage changing from 0
to 9 kV, 50 times a second (just to be sure everybody gets it). Because
everything works fine this proves that TCs can be fed by DC: the primary
capacitor doesn't need to be charged with varying polarity cyclically.
Now, we can imagine a tank DC supply with a bridge rectifier and a huge
flyweel capacitor (e.g. 10 uF) using e.g. a pig. The pig primary would be
current limited according to the flyweel capacitor value. This DC supply
would be connected to rest of the primary circuit (capacitor, spark gap,
primary coil) as usually, but through a second current limiter, this time
set to charge the primary capacitor in a time smaller then the time between
bangs of the rotary spark gap. This will also protect the flyweel capacitor
from discharging too much when the spark gap fires.
Having a variac on the pig primary would allow to directly set the tank
output voltage and we would be sure that the primary capacitor is always
able to get charged to that voltage before every bang.
This means that we'll know precisely at what voltage the primary cap is
charged i.e. we'll know exactly how much POWER we'll pump into the primary
coil at each bang (forget about the losses for now).
We could than easily investigate the effect of bang repetition rate without
bothering about the AC tank voltage, the bang phasing, the tank supply
What about that?
Another thing that I don't get is why TC power requirements are usually
defined as tank supply voltage and its current limit value: wouldn't it be
more exact to speak about power (Joules) required by the primary winding
(easy to calculate from primary cap value and its charging voltage) or the
energy required (multiply by the BPS) ?
Eventually the most important thing that matters (again, forget about
losses) is how much energy is stored in the primary capacitor, not its
charging voltage, to define how much energy we are pumping into the primary
coil, isn't it?