booth said:
Homer J Simpson yazdi:
Discharge happens at a rate of 2Hz. we have 500msec for charge. 2
different capacitors are used, 40nF and 1.2uF.
Since you want to charge a capacitive load, it seems like you should
consider ways that do it quickly and efficiently. I believe it's
Linear Technology that's been advertising an IC lately that does a good
job charging photoflash caps. There are enough external components
that it can be tailored to a pretty wide range of energy (and voltage)
levels. There may well be other manufacturers that make similar
products.
Though a standard TV flyback transformer is unlikely to do the job for
you, the people who make them do know how to make high voltage
transformers. I would certainly look at getting transformers from a
company like that, that already understands the art, the technology.
The power level you're talking about is a bit more than, but not out of
line with, the power handled in the horizontal output transformer of a
large CRT display, though in a CRT display, much of the power goes into
horizontal deflection.
Also, have you considered resonant charging? Is that a possibility?
That's a lot more "gentle" on the supply than dumping an uncharged
1.2uF suddenly across a fixed-voltage supply. It sounds like the goal
is not to make 30kV, 10mA power supplies, but to charge capacitors.
10mA would charge the 1.2uF cap at about 8000V/second, so it would take
a bit under 4 seconds to charge it, assuming the supply is
current-limited at 10mA. Resonant charging could recharge it much
faster, though it takes a rather large choke, capable of storing about
135 joules in this case, to put 540 joules into the 1.2uF cap.
I'm curious: what's the peak current in the capacitor when it's
discharged? Is it a special capacitor that's rated for pulse discharge
service?
Sounds like you do have an understanding about working with high
voltages, but as others have done, I must add: the energy level
represented by 30kV on a 1.2uF capacitor is easily lethal, and that
voltage can jump long distances. Please be very careful working around
stuff like that! For the inevitable lurkers who are getting ideas
about playing with things like this in their home workshop...please
DON'T.
Cheers,
Tom