Generating a High Voltage Pulse

[[email protected]]

Hi everyone, I'm new here. My name is Brick and I'm taking my first
electronics course right now. My teacher recommended checking out this
usenet group.

I'm trying to generate a high voltage pulse in a circuit that is
running off of a 5 volt power supply. Ultimately this will be put
across a spark gap and used as an ignitor. I guess probably around
1000v would be a good potential difference. The first thing that jumped
into my mind was a transformer with a capacitor, but I don't think that
this is the way to go. The idea that I'm toying around with now is
trying to use the piezoelectric crystal from a lighter. I'm basically
trying to generate the exact same spark so it seems right on. I think
that I could use a small solenoid in conjunction with the spring
already in the lighter, but I would prefer to do something more
graceful if possible. Could I possibly find a piezoelecric crystal that
requires a low voltage input and physically put it up against the
crystal from the lighter?

Maybe I could do it with capacitors? After doing a little research on
google this seems like a viable option (Cockroft-Walton voltage
multiplier).

Does anyone have an advice for me? I'd prefer to do this in the most
compact way possible, and I'm sort of leaning towards the salvaged
crystal from the lighter for this. Maybe there's another way that I'm
totally missing. Anything you have to offer is greatly appreciated.

 

[Chris]

Hi everyone, I'm new here. My name is Brick and I'm taking my first
electronics course right now. My teacher recommended checking out this
usenet group.

I'm trying to generate a high voltage pulse in a circuit that is
running off of a 5 volt power supply. Ultimately this will be put
across a spark gap and used as an ignitor. I guess probably around
1000v would be a good potential difference. The first thing that jumped
into my mind was a transformer with a capacitor, but I don't think that
this is the way to go. The idea that I'm toying around with now is
trying to use the piezoelectric crystal from a lighter. I'm basically
trying to generate the exact same spark so it seems right on. I think
that I could use a small solenoid in conjunction with the spring
already in the lighter, but I would prefer to do something more
graceful if possible. Could I possibly find a piezoelecric crystal that
requires a low voltage input and physically put it up against the
crystal from the lighter?

Maybe I could do it with capacitors? After doing a little research on
google this seems like a viable option (Cockroft-Walton voltage
multiplier).

Does anyone have an advice for me? I'd prefer to do this in the most
compact way possible, and I'm sort of leaning towards the salvaged
crystal from the lighter for this. Maybe there's another way that I'm
totally missing. Anything you have to offer is greatly appreciated.

Hi, Brick. If you can use 12V instead of 5V, you'll be able to do
quite a few things with an automotive ignition coil (available at any
junkyard).

As a new electronics student, you may want to take a look at some of
the best hobbyist circuit collection sites if you're scrounging for
ideas:

http://ourworld.compuserve.com/homepages/Bill_Bowden/

http://www.uoguelph.ca/~antoon/circ/circuits.htm

http://www.commlinx.com.au/schematics.htm

There are a lot of good ideas here (especially in the first site) for
hobbyist circuits with ignition coils.

Good luck
Chris

 

[mc]

Hi, Brick. If you can use 12V instead of 5V, you'll be able to do

quite a few things with an automotive ignition coil (available at any
junkyard).

In fact, there's no reason an ignition coil wouldn't work with 5 volts
input, producing 5/12 as much voltage, which might be enough.

As I recall, an ignition coil is a transformer with the 2 coils connected
together at one end (so that it has only 3 terminals) and a very high
step-up ratio.

 

[Chris]

In fact, there's no reason an ignition coil wouldn't work with 5 volts
input, producing 5/12 as much voltage, which might be enough.

As I recall, an ignition coil is a transformer with the 2 coils connected
together at one end (so that it has only 3 terminals) and a very high
step-up ratio.

Hi, MC. You're right -- the ignition coil *will* work with 5V,
producing a lower output voltage.

However, some of the hobbyist circuits use power MOSFETs which need the
higher gate voltage to turn on. I suppose the OP could substitute
logic level power MOSFETs and make other changes in the circuits as
needed, but I thought it might be easier for the OP just to use a 12V
supply and go with the existing circuits.

Good luck
Chris

 

[[email protected]]

Thanks guys. Those sites look like they have some fun projects on them
and I'll try to check through them before I ask questions from now on.
I saw the relevant circuits with the ignition coils too. This looks
like a possibility to fall back on, but is there a smaller option? Is
physically connecting two piezoelectric crystals a waste of time? It
just seems so nice that it would be so tiny if it worked.

 

[Bill Bowden]

In fact, there's no reason an ignition coil wouldn't work with 5 volts
input, producing 5/12 as much voltage, which might be enough.

As I recall, an ignition coil is a transformer with the 2 coils connected
together at one end (so that it has only 3 terminals) and a very high
step-up ratio.

An ignition coil works more like an inductor than a transformer and you
might get just as much spark energy from 5 volts as 12.

The stored energy is 1/2 LI^2 and the current rises as I =(E T ) /L
So, if you apply half the voltage for twice the time, you get the same
current and stored energy. So, a 12 volt coil will probably work on a 6
volt system, but the RPM would only be half as much for the same spark
energy.

-Bill

 

[Joerg]

Thanks guys. Those sites look like they have some fun projects on them
and I'll try to check through them before I ask questions from now on.
I saw the relevant circuits with the ignition coils too. This looks
like a possibility to fall back on, but is there a smaller option? Is
physically connecting two piezoelectric crystals a waste of time? It
just seems so nice that it would be so tiny if it worked.

Piezos work as well but they are only widely available for cigarette
lighters (and only as long as smoking isn't banned everywhere...).
However, they operate on mechanical stress which I guess you don't want
here.

Smaller HV transformers: These can be found in little portable TVs. The
ones with a "real" CRT that is the size of a postcard. Sometimes you can
find little HV transformers from military surplus or in the starter
circuitry of small oil and gas furnaces. Check a place that does
maintenance on these, maybe they could save an old board they swapped.
Of course, you can always wind you own but last time I did that I had
blisters that hurt for days.

Regards, Joerg

 

[Matt]

Hello [email protected],

Hi everyone, I'm new here. My name is Brick and I'm taking my first
electronics course right now. My teacher recommended checking out this
usenet group.

I'm trying to generate a high voltage pulse in a circuit that is
running off of a 5 volt power supply. Ultimately this will be put
across a spark gap and used as an ignitor. I guess probably around
1000v would be a good potential difference. The first thing that
jumped into my mind was a transformer with a capacitor, but I don't
think that this is the way to go. The idea that I'm toying around with
now is trying to use the piezoelectric crystal from a lighter. I'm
basically trying to generate the exact same spark so it seems right
on. I think that I could use a small solenoid in conjunction with the
spring already in the lighter, but I would prefer to do something more
graceful if possible. Could I possibly find a piezoelecric crystal
that requires a low voltage input and physically put it up against the
crystal from the lighter?

Maybe I could do it with capacitors? After doing a little research on
google this seems like a viable option (Cockroft-Walton voltage
multiplier).

Does anyone have an advice for me? I'd prefer to do this in the most
compact way possible, and I'm sort of leaning towards the salvaged
crystal from the lighter for this. Maybe there's another way that I'm
totally missing. Anything you have to offer is greatly appreciated.

Ever think of modding a old disposable camera flash? Its triggerable and
has a low volt drive. Trying googling it.

http://www.angelfire.com/80s/sixmhz/camera.html

 

[Roy L. Fuchs]

Ultimately this will be put
across a spark gap and used as an ignitor.

A simple transformer (or even a large inductor) and a battery will
work. When you apply the battery, a magnetic field is exhibited. It
is a "standing field" (non-moving, no transformation). The HV occurs
(on all windings) when you remove the battery and the field collapses
back down into the core. It can be several thousand volts, and can
even have a sharp kick current wise. In fact, this is how old
automotive spark plugs were fired. Close points, coil is energized...
open points, spark fires.

I even made a "Lie Detector" this way once. (I was the determining
factor on truth or lie) (I liked shocking people). Tee Hee Hee!

 

[Roy L. Fuchs]

In fact, there's no reason an ignition coil wouldn't work with 5 volts
input, producing 5/12 as much voltage, which might be enough.

As I recall, an ignition coil is a transformer with the 2 coils connected
together at one end (so that it has only 3 terminals) and a very high
step-up ratio.

A typical 30,000 volt ignition coil will make well over 1000 Volts,
even if only a D cell at 1.5 Volts is used.

 

[Chris]

Hello [email protected],


Ever think of modding a old disposable camera flash? Its triggerable and
has a low volt drive. Trying googling it.

http://www.angelfire.com/80s/sixmhz/camera.html

Or just get a flash camera at a garage sale and take it apart for what
you need.

Flash assemblies use an oscillator to create an intermediate voltage
(usually 300-400V), That's the audible whine you hear as the flash is
being charged up -- it works at a high audio frequency. The camera or
strobe then uses a triggering transformer to create the arcover voltage
(4KV) for the flash lamp when you press the button on the camera. Once
the arc has been established, the 300-400V on the cap is discharged
through the flash lamp, giving the energy for the intense flash.

If you want to roll your own, you'll find the transformer (and some
flash lamps) on p.78 of the current Mouser catalog.

http://www.mouser.com/

If you choose an appropriate small series resistance simulating the
series impedance of the flash lamp, you should be able to get a great
arc without burning out the trigger transformer. Don't run this
without a small non-inductive resistor -- you *will* smoke the small
trigger transformer.

You can google the circuit to get the 300V from the 5V supply.

Here's something to get you a start, that apparently works with a 9V
battery:

http://www.discovercircuits.com/PDF-FILES/xenfls1.pdf

Good luck
Chris

 

[Jasen Betts]

Hi everyone, I'm new here. My name is Brick and I'm taking my first
electronics course right now. My teacher recommended checking out this
usenet group.

I'm trying to generate a high voltage pulse in a circuit that is
running off of a 5 volt power supply. Ultimately this will be put
across a spark gap and used as an ignitor. I guess probably around
1000v would be a good potential difference. The first thing that jumped
into my mind was a transformer with a capacitor, but I don't think that
this is the way to go. The idea that I'm toying around with now is
trying to use the piezoelectric crystal from a lighter. I'm basically
trying to generate the exact same spark so it seems right on. I think
that I could use a small solenoid in conjunction with the spring
already in the lighter, but I would prefer to do something more
graceful if possible. Could I possibly find a piezoelecric crystal that
requires a low voltage input and physically put it up against the
crystal from the lighter?

easiest would be an automotive ignition coil, 5v in should get you much more
than 1000V out. you'd need some sort of circuit to switch it on and off...
to cause the spark...

Maybe I could do it with capacitors? After doing a little research on
google this seems like a viable option (Cockroft-Walton voltage
multiplier).


Does anyone have an advice for me? I'd prefer to do this in the most
compact way possible, and I'm sort of leaning towards the salvaged
crystal from the lighter for this. Maybe there's another way that I'm
totally missing. Anything you have to offer is greatly appreciated.

I saw a lighter that had a coil based ignitor, it used a 12V supply and
small traansformer.

those piezos may not last long, but I've always had the plastiic mounting
fail on me so I can't be sure.

helium-neon lasers need a high voltage to run, you may find something
useful on a web-site that deals with lasers and hologtaphy, but these days I
suspect most are using semiconductor lasers for that.

another option is the high voltage trasnsformer from an old CRT-based
monitor or TV... Again it'll need some sort of switching typically thses
have a three stage Cockroft-Walton multiplier built in (unless it's a
extremely old TV)

Bye.
Jasen