10kv and 30kv capactor plates / General Science and Electronics / Forums

Forums

4hv.org :: Forums :: General Science and Electronics

« Previous topic | Next topic »

10kv and 30kv capactor plates

previous 1 2 3 next

Move Thread

LAN_403

Proud Mary

Wed Dec 18 2013, 10:35PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Andy wrote ...

I think I understand it.
Was planning on building a marx and trying to get the output to feedback into the stages with a transformer supplying the difference. If there is three plates, the middle one +15volt with the left side -15volt the left side is connected in series with the next capacitor and then connected to the right side which is in parallel of the two capacitors.

If that makes sense

It's always helpful to make a circuit diagram of a new idea; it clarifies the arrangement in your own mind, and makes it much easier for others to give you a useful opinion.

Ask yourself what is the exact purpose of each component, and how circuit operation would change if a particular component were removed or had its value changed.

Andy

Fri Dec 20 2013, 06:34PM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
Location:
Posts: 874

Hi, Merry christmas to all

The picture was the rought idea, it should go from 3kv to 9kv(with a spark gap from ground to the top ones).

Electra

Fri Dec 20 2013, 11:05PM

Registered Member #816 Joined: Sun Jun 03 2007, 07:29PM
Location:
Posts: 156

Oh now we can see what youâ€™re talking about:- Itâ€™s a diode charged Marx bank right?

Donâ€™t think itâ€™ll work as it stands. The upper and lower rows of capacitors are connected together to two different 1000v rails. This is doing nothing and if the circuit was working would stop the output rising.

Also it wonâ€™t work using two strings of diodes like that, one will always conduct when it fires shorting itself out, and you need to replace one side with resistors at least. You might also need resistors in series with the diodes to prevent the rapid voltage reversal causing a current spike as the diodes recover (possibly I donâ€™t know).

You donâ€™t need two supplies of the same voltage and polarity. Will your spark gaps work reliably at 1000v or did you mean to put 10kv.

Andy

Fri Dec 20 2013, 11:40PM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
Location:
Posts: 874

About the spark gaps, was going to use a thin threading needle and have it 0.5-1mm apart, not sure but 1kv to 2kv would hopefully be the range.

The top and bottom row, should get + 3kv from the output, with 1kv in the middle of the series string, I haven't added diodes for them yet, I might have to have the diodes going to ground from each leg instead of across ground can't test it with a sim at the moment.

The thing was meant to be two banks, the output of one charges the other. I thought that 2kv across two series capacitors, the middle would be at 1kv, if there is three...

Thanks for the info, still working on it.

EDIT

Electra

Sat Dec 21 2013, 12:13AM

Registered Member #816 Joined: Sun Jun 03 2007, 07:29PM
Location:
Posts: 156

Andy the concept of a Marx driving another Marx is flawed, as if you think about it the output pulse is essentially short, while the capacitors need to be charged constantly until their voltage is sufficient to jump the spark gap.
But you can use a CW voltage multiplier to feed the Marx. Or better use a higher voltage supply to begin with.
The main point of the Marx is when you want a higher voltage pulse than you can get with a single capacitor charged form the most suitable supply you can build for your application.. Otherwise your really no better off than connecting all the capacitors in series/parallel the energy will be the same.

Andy

Sat Dec 21 2013, 01:34AM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
Location:
Posts: 874

True that, was planning the stages to fire multiable times, say without losses the first level 3 times,then 3 the second level with 9 the first,3,9,27....

Proud Mary

Sat Dec 21 2013, 03:05PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

It's always a good idea to construct a narrative to explain what happens in a circuit from the moment power is applied: e.g. C1 is charged by R1 until 90V, whereupon NE1 fires and discharges C1 through R2.

It can also help to write on the diagram the voltages expected to be found at key points at any given time, or part of a cycle, during correct operation.

Andy

Sat Dec 21 2013, 07:13PM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
Location:
Posts: 874

Have drawing it on paper, got the sim up and running, it seems to work

Electra

Sat Dec 21 2013, 08:31PM

Registered Member #816 Joined: Sun Jun 03 2007, 07:29PM
Location:
Posts: 156

Ok referring to your earlier diagram (on Fri) I think I see what the intention is/was here you are trying to make the first stage dual purpose? So you have 2kv x3 from the bottom stage feeding the upperstage of the opposite side with 6kv which is itself combing with the 2kv form its lower stages to give 8kv per stage. What, have you entered a competition to see who can make the most complex high voltage power supply!

As for the last simulation dia, what are the waveforms like? Could you add a scope shot of every stage? I still think youâ€™ll run into problems with S1 shorting the supply through D4 and D1 in real life, anyone else see this?

P.S.

I hope Iâ€™m not coming across as being too negative about your ideas, was just trying to highlight anything you might not have considered.

Andy

Sun Dec 22 2013, 05:35AM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
Location:
Posts: 874

Hi Electra, sorry but I can't get into Virtualbox, it keeps crashing through lack of ram, after closing most things down, it got the sim in it.

previous 1 2 3 next

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob