A toroid will actually shield the secondary slightly

Thanks, for those nice images

I'de like to put such HV stuff in the garden, so looking for extreme high voltages but at low current, and since it should be quite easy estimate capacitance of aluminium ball at given diameter (lets say 1 meter),

hyperphysics: Isolated Sphere Capacitorwhere

hyperphysics: Potential: Charged Conducting SphereSome tables

Dielectric Constants at 20°C.

After

it gives me for 1 meter sphere

~~111 pF capacity~~.

Update:

*Ups, this was calculateted for 2m in diamater sphere, since I'me made mistake and substitited radius with diameter * Capacitance of charged sphere at given diameter will be: R:=D/2

Cd(D):= 4*pi*e0*D/2= 2*pi*e0

Cd(D) ~ 56 pF *D

So, for

**1m (in diameter) sphere we have: 56 pF capacitance.**I've found 10kV 100pF capacitors and 16kV 20ma diodes, so probably will try build Dickson voltage multiplier using such components with flyback output current limited by two 10kV 10MOhm resistors.

Quick estimation of energy in 100kV dickson made of 10kV capacitors gave me estimated amount of stored energy at 100kV based on 10kV VDC PSU ~275mJ using 100pF caps in each of ten stages which is not so high when we compare with 500mJ of charged car, etc

It looks like enrgy in Disckson voltage multiplier, when 10kV caps in series will be used in next stages up to 100kV we have formula for amount of energy in each stage:

Ek=E0*k, where E0=1/2*C0*V0^2, C0=100pF, V0=10kV, so E0= 5mJ, when 100pF capacitor will be charged to 10kV ....

End of update -time to order elements and build this thing

What could be capacitance of those touruses you use in your TC's?

When we have capacitance and know voltage than we could estimate amount of energy and try to determine maybe from some regulations for HV stuff if such capacitance at given HV level is safe if discharge not repeted more than lets say 1Hz, however it ould be better have at least 100Hz discharge rate for visual effects...

111 pF @ 100kV gives ~ 0.556 J = 556 mJ of energy.

Howto estimate is it safe to touch and discharge by hand such charged sphere at not more than 1 Hz rate?

When we assume than we discharge via 1k resistance than we get 3RC constant ~ 333 ns ~0.3ms ....

Than, when we calculate amount of charge at 100kV we have: 111pF * 100kV ~ 11.1 uQ , so dividing this charge by discharge time 0.3ms we get average current: ~

**33.3 mA** within less than 1ms , so less than 100mA, but magnitude higher than 1mA, but discharge time less than 1ms... Hot could affect person who touches such HV ball lifted 1 meter above ground?

Such huge charged ball looks a little bit scary... no plans touch it without clear evidence prooved by some safety rules that it might be safe or maybe it isn't even at lower than 1 Hz rate-from time to time....

Maybe old school

Van de Graaff generator powered by small wind turbines could be better option (more safe) than TC which might require much more power and provide much more power, I guess?

A Van de Graaff generator is an electrostatic generator which uses a moving belt to accumulate electric charge on a hollow metal globe on the top of an insulated column, creating very high electric potentials. It produces very high voltage direct current (DC) electricity at low current levels.

Trying to figure out what could be maximum possible potential to achieve on 1 meter in diameter aluminium sphere (ball) lifted ~ 1 meter above ground, but in the garden, not inside building.

There are many factors which influence this air breakdown voltage, but we could asume eg. 15*C dry air...

Anyway, when we calculate capacity of such sphere, than probably easier to test this than calculate at very changing outside air atmosphere conditions, but to do this I need at least Van de Graaff generator or maybe TC could do this job too, if we protected TC seconday somehow?

What about... put whole TC inside such quite big 1 meter in diameter aluminium sphere (I mean with battery and circuit ) and leave only well insulated wire to earth to be able create potentials difference between lifted ball and earth?