most simple and smallest way to charge a 6kV capacitor?

Hi again,

I need some ideas on what type of DC-DC or DC-AC converter I can use to convert 9V into 6kV.
the 9V will be a standard 9V battery. The output current doesn't need to be high. It's for charging a 6kV capacitor, and this May take a few seconds.
It doesn't need to be charged in a few milliseconds.

My own suggestions are these:
- DC-DC booster (switching a coil to get high voltage spikes) but these only generate 200V max I think
- DC-AC inverter like those small CCFL inverter circuits
- Flyback - not compact enough
- booster or inverter connected to a marx generator - but also not compact enough
- ...

any other ideas?

It also doesn't matter if the output is AC or DC, I'll just add a HV diode to rectify it. Although, that also takes some space and it has to be Really compact.

I know that converting 9V into 6kV might not sound like a simple thing, at least if I want to do it in one stage, but I've seen videos where people convert the voltage from a 1.5V battery into 4inch sparks. (that was with a marx generator too though).

Comments

[rocketman221]

You might look at a flyback transformer from a small portable crt tv.
For something smaller you could use trigger coils from camera flash boards, but you will need 300 volts and a circuit to drive them. I have gotten a good output by wiring a dozen in parallel. You could power them from one of the camera boards.

[Electorials]

Do you mean to use one driver board to drive a few trigger coils? I don't really understand it.

[rocketman221]

Yes, one camera flash board can supply enough power to run several trigger coils. The trigger coils only provide tens of micro amps of current so more than one is needed. However the trigger coils are very small. They can be pulsed at around 50hz to provide continuous output.
To charge a capacitor you will need a high voltage diode between the trigger coils and the capacitor to prevent the trigger coils from discharging the capacitor.
I have done this before and it will charge a leyden jar. I have a large string of trigger coils in parallel. I was discharging a 4uf capacitor into the primaries to make them work. The capacitor was being continuously charged by a camera flash board.

[Electorials]

http://en.wikipedia.org/wiki/Trigger_transformer

your talking about this right?

I think I have one or two of those tiny things laying around. I didn't know they could generate 2kV sparks!

Do they really work that well that you can get a spark from them?
I'll test it out tomorrow :) thanks for replying!

[rocketman221]

Yes those are the transformers.
I made a quick video of mine. They put out more than 2kv though. I was powering them with a camera flash board and a 0.22uF capacitor.
I couldn't find the driver I used before so I just switched them by hand. I was able to get enough voltage to arc clear across the trigger coil with a 500v input. My trigger coils are rated for 4kv at 330v input, but didn't mind higher.

[iceng]

Why not do it by Hand ? ! !  .  .  .   A

[Electorials]

can you also create that yourself?

[iceng]

Principle of  pressure ( image #1 )
squeezing the actual crystals ( image #2 ) is straight forward.
Only the ( 3d picture ) is an unknown to DIY, perhaps an automatic
mechanical compression compensation device ?

A

[Electorials]

I think it's just a simple lever to squeeze them more easily.

[frollard]

6kV is a lot for a 9v to pull off; again, since the voltage is ridiculously bigger than the source, the amperage at the source must be big.

What exactly do you want to make and perhaps we can help with a more specific solution. You already have the best answer with the switching booster -- just feed that to a voltage multiplier to get more voltage.

[Electorials]

in fact 6kV is not redicalous, thinking that there are stun guns that generate 500kV with ease.

The current doesn't need to be high because the capacitor may charge over a long time period. This would allow the current, for charging them, to be lower.

It's for igniting a gas mixture. I would need a 1 to 2cm thick spark.

[Alex1M6]

Actually stun gun voltage is always over rated by the manufacturers sales department, most can put out around 25kV max. You could use a flyback transformer out of a plasma globe as they are usually small enough to fit inside of a project box. See this video where the uploader uses a 9v battery to power a regular flyback using a single transistor, however this driver is less than efficient but it proves a 9v can give high voltage. 

http://www.youtube.com/watch?v=w8d0GorQmrY

[Electorials]

good
I think that's at least 6kV.

but I should get it more compact than that.

[Alex1M6]

Get your self a cheap plasma globe and rip the mini flyback out of it, they are usually pretty small in size ( :

[Electorials]

I have one of those but it's still too large. The driver for it would also take too much space.

[Alex1M6]

Ok, well I just uploaded a video of it anyway to show you.

http://vimeo.com/33282988

[Electorials]

mine looks just the same :)

Haha, I just got a 20cm spark from a flyback xD


I charged up a 250V capacitor and then connected it to the primary of the flyback.
It was nice :) and works on a 9V battery.
but it also involves a flyback and capacitor that take too much space :( it has to be really compact!

[Electorials]

I meant 10cm :) typo

[LargeMouthBass]

If igniting a gas mixture is your intent, then you shouldn't need anything too spectacular. You only need a small short arc.

If this is a potato cannon type application where the gas in is the chamber of a unit held by the user, then the piezo type ignitor used on propane barbeque grills is a good choice. Those types don't even need any batteries.

If you need electronic control, you could get one of those super cheap bug zapper "tennis racket" toys. They have a small PCB inside that generates about 1800V from 3V.

[Electorials]

I know I could use the CCFL inverters or tennis racket zappers but the voltage is mostly not large enough. You can get a 0.5cm spark but only after getting closer than 1mm and then separating the electrodes until 0.5cm.
That's the bad thing about them.

[steveastrouk]

A 9V battery is a pretty poor source to drive a PSU capable of generating 6kV, once losses are taken into account.

There is NOTHING to stop a "flyback" being compact enough for what you want to do.

Steve

[Electorials]

how about a small AC inverter and a Cockcroft–Walton generator?

And do you mean I could make a tiny flyback myself?

[steveastrouk]

C+W are very inefficient

[Electorials]

and a marx generator?
however that would also need a high input voltage.

[steveastrouk]

Yes.