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Chaining transformers for a high voltage pulse?

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Artlav

Sun Feb 22 2015, 03:00PM

Registered Member #8120 Joined: Thu Nov 15 2012, 06:06PM
Location: Moscow, Russia
Posts: 94

Is it possible to connect several transfromers into a chain?
That is, the secondary of the first one connects to the primary of the second one.

The idea is to produce a high voltage pulse from low voltage.
Akin to this:
Da1ff708a15b

Only the secondary of the transformer is fed into the next one.

Two cases i can think of:
1. Xenon light bulb needs tens of A of current. The (series) ignition transformer's secondary should be able to carry it, so you can't put too much turns on it.
What if the secondary would only be a dozen turns, with a primary of 2-3. which is then connected to another transformer of a much thinner wire with 100:1 turn ration?

2. Using 12V input instead of 300V in the circuit above - the first transformer would produce a pulse of about 200V, fed into the next one, that would produce the kv range pulse.

Would either of these work?
How do you calculate it?
I'm mostly interested in (1),

Ash Small

Sun Feb 22 2015, 07:36PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

What kind of pulse are you after, can you be more specific?

I'm working on something simar here:

There have been a few threads here recently redarding seriesed secondaries.

The design I'm working on uses toroidal cores with one turn primaries, with the secondaries wound through all the cores. (this is for pulses around 100nS) I'm hoping to get some superfast 1000V MOSFET's soon so I can try it.

Artlav

Sun Feb 22 2015, 11:12PM

Registered Member #8120 Joined: Thu Nov 15 2012, 06:06PM
Location: Moscow, Russia
Posts: 94

A 150W xenon arc lamp:
Xb Lamp

It needs several KV (5-10) for ignition.
The only way i can think of is to put it in series with a transformer, akin to this:
Sch

It works with a HV supply on the primary side (a capacitor is charged up from a taser transformer to a few KV, then spark gap closes it into the primary, producing the pulse on the secondary), but i want to get rid of the large exotic components and use a simple pulse generator like in post 1.

However, the secondary in there should be able to carry about 8A, which greatly limit the amount of turns i can put on it.

Therefore, the idea of chaining several transformers together to get more voltage from less, i.e.:
N1nUf5C

Patrick

Sun Feb 22 2015, 11:37PM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

Are you wanting 12V primary to 1200 to 6000 ?

Artlav

Mon Feb 23 2015, 12:01AM

Registered Member #8120 Joined: Thu Nov 15 2012, 06:06PM
Location: Moscow, Russia
Posts: 94

Patrick wrote ...
Are you wanting 12V primary to 1200 to 6000 ?

Yes, apparently.
Or any other straightforward way of getting an in-series 6KV pulse from 12V.

Patrick

Mon Feb 23 2015, 04:25AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

But you need a "striking" voltage, then a low voltage high current continuous . right?

Shrad

Mon Feb 23 2015, 08:28AM

Registered Member #3215 Joined: Sun Sept 19 2010, 08:42PM
Location:
Posts: 780

look at sam's laser faq, homemade ion laser power supply

it provides a starting pulse of 10+kV and a sustain I/V of dozens of amps and 200-ish volts

Artlav

Mon Feb 23 2015, 10:44AM

Registered Member #8120 Joined: Thu Nov 15 2012, 06:06PM
Location: Moscow, Russia
Posts: 94

Patrick wrote ...
But you need a "striking" voltage, then a low voltage high current continuous . right?

Right.

Shrad wrote ...
look at sam's laser faq, homemade ion laser power supply

That looks interesting, and is pretty much what i had in mind.
However it takes 400V, while mine should run from 12-24V.
Now getting 400V from 12V is not that difficult, but i was wondering if there is a simpler way, like two transformers in a chain.

Also, i've redrawn that schematic and got a bit confused - what he calls a return path for the pulse is located pretty much where the power supply's own output capacitor would be.
What is the trick there?
VKnHONL

Artlav

Mon Feb 23 2015, 11:00PM

Registered Member #8120 Joined: Thu Nov 15 2012, 06:06PM
Location: Moscow, Russia
Posts: 94

Meanwhile, the circuit basically works.
However, i get two problems:
-Neon lamps burn out. It would trigger a hundred times, then cease to trigger.
Is there a variant without a neon lamp, or perhaps some other kind of spark gap that can take the punishment?

-The pulse is highly variable.
It can be tiny, it can be big. It is often big if i short the capacitor, it rarely works with SCR doing the discharge.
I'm not sure what is going on there.

RateReducer

Mon Feb 23 2015, 11:02PM

Registered Member #4603 Joined: Wed Apr 25 2012, 07:33PM
Location: Austria
Posts: 159

Hi.
You can use a ferrite ring core transformer. 10 turns (thick wire) secondary, 1 turn primary. On the secondary side you have the transformer wired in a series connection to your lamp + supply and on the primary you have a HV transformer e.g. a flyback, a HV capacitor and a spark gap. When you turn on the HV transformer the cap charges, the spark gap fires and you get a HV pulse inside your lamp that can be used to fire the lamp.

Thats the way i did it with my arc lamp.

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