Generating 30,000V+ from a 9V battery?

[Burningmace]

I've heard it's possible to generate rediculously high voltages from just a single 9V battery, even if it's for only a few milliseconds.

If I were to take a guess, I'd suggest somehow generating an AC signal from the battery (oscillator?) and putting it through a transformer. However, I'd expect that the current demand on the input side of the transformer would be so high even for very small loads that it'd melt everything.

Ideas?

 

[blueroomelectronics]

What is it for?

 

[kpatz]

There are a few ways of doing it. Are you looking for a brief pulse of 30kV or continuous (albeit very low current)?

Brief pulse: charge capacitor w/battery, discharge capacitor through a transformer.

Continuous: Use an oscillator and a transformer.

Needless to say, the amount of current you'll get at 30kV will be only a few microamps at best, or milliamps using the capacitor pulse method (this is similar to how xenon camera flashes work). Actually, xenon flashes use a combination of the above two: an inverter charges a cap up to a few hundred volts, then the cap is discharged through a coil that bumps the voltage up to several thousand volts to ionize the gas in the flash tube.

 

[wejos]

maybe stun gun

 

[Boncuk]

HV can also be generated by using a cascade as shown in the attachment.

Each stage of the cascade will add to the original voltage.

Shown is a three stage cascade.

 

[Space Varmint]

HV can also be generated by using a cascade as shown in the attachment.

Each stage of the cascade will add to the original voltage.

Shown is a three stage cascade.

That's a voltage multiplier arrangement. You cannot expect much current from that sort of configuration without some sort of pass transistor.

What you want to do is build an oscillator and use a large ferrite core as a transformer. Here is a simple single stage converter I have poster a few times. The transistor is a 2N3055 and the core is an Amidon ferrite core about 1 inch outer diameter using number 43 mix. The turns ratio is around 12 to 800 turns and delivers about 2000 volts.

There are many arrangements and configurations. For really high power most use IGBTs. This is just something to help you understand the concept which is by building an oscillator you are effectively transforming the DC voltage into AC which can be converted to a different voltage level through the use of a transformer.

 

[Burningmace]

I'm only looking for a single pulse, and I basically want as high a voltage as possible. A megavolt would be pretty cool. I don't actually care if this is a single use circuit, I just need as big a voltage as possible for at least 2ms. I can use two 9V batteries if it'd help.

The application will be somewhat similar to a camera flash, and kpatz's idea looks good. Could I basically charge a 10,000uF capacitor and then switch its output to a transformer using a transistor?

Also, anyone know the rough voltage that your average disposable camera flash puts out?

 

[Papabravo]

I sense a potential winner of a Darwin Award. Please take appropriate precautions.

 

[blueroomelectronics]

What's wrong with using a camera flash circuit? Why do you need 30kV or more?

 

[Burningmace]

I sense a potential winner of a Darwin Award. Please take appropriate precautions.

Hahaha, I was waiting for someone to say that. Don't worry, I'm not an idiot and I know that 30kV isn't something to be toyed with.

blueroomelectronics - It's for a project I'm working on. Basically I need to produce as high a voltage as possible from a battery, even if it destroys the circuit in the process.

 

[blueroomelectronics]

Ok so tell us what your project is supposed to do, perhaps we can find a simple solution?

 

[Burningmace]

It's supposed to generate a really high voltage from one or two 9V batteries.

 

[blueroomelectronics]

Ahh, and what current you need? Are you trying to make a spark?

 

[Burningmace]

One microamp or higher should do the trick, as long as I can produce 30kV or so. The higher the voltage, the better.

 

[Papabravo]

The circumlocution in this thread is beginning to make my head spin. Why can't you just be straightforward and tell us what earthly good it will be to produce a pulse -- one time only -- that destroys the circuit.

 

[Burningmace]

Sorry I'm being so avoidant. It's a bet between me and a friend. I'm keeping quiet as to the details because he's likely to Google our bet and find this page so he can see how I'm going about it. Silly, I know, but there's pride at stake here!

The short story is that it doesn't really matter what I want to do with it, but how to actually go about doing it.

 

[blueroomelectronics]

What are the conditions of winning the bet? How do you plan to measure 30kV?

 

[Burningmace]

It's not a bet for who can produce the highest voltage from a 9V battery, so we don't need to measure it.

Treat this as a hypothetical excercise - if you had to create the biggest voltage you could from a 9V battery (or two), how would you do it?

 

[birdman0_o]

A simple way would be to hook the battery directly to a step up transformer with a push button in between, the push button would have a nice one shot of flux.

 

[tcmtech]

Standard issue ignition coil from a newer vehicle can easily do 30 KV. Just use the 9 volt battery to charge up a HV poly cap to a few hundred volts with a old camera flash circuit.
The camera flash circuit may need a voltage regulator to keep the 9 volt battery form burning it up. Some old ones would take 9 volts for Short Burst some wont.