~50KV from 1 CR123 3V Battery / High Voltage / Forums

Forums

4hv.org :: Forums :: High Voltage

« Previous topic | Next topic »

~50KV from 1 CR123 3V Battery

1 2 3 next

Move Thread

LAN_403

Hotwired

Sun Aug 07 2011, 04:11AM

Registered Member #4049 Joined: Sun Aug 07 2011, 03:50AM
Location: UK
Posts: 14

If this is not a new design do say.

Essentially it works on the same principle as a stun gun. Except its possible to construct from everyday objects and a couple of cheap mail order components.

1) A tiny oscillator circuit from a disposable flash camera is used to bump up 1.5-3V to 350V

2) A 0.22uf metal foil capacitor is charged to ~350V

3) A spark gap in the form of a gas discharge tube, in series with the capacitor and a HV coil is set to arc at 350V

4) Every time the capacitor hits ~350V the spark gap arcs and pulses the HV coil

How to:

First you need the capacitor charging circuit from a disposable camera. Any will do but the easiest way is to get a Kodak Fun Saver camera. The Wedding and Custom Kodak cameras are the same thing by the way.

Get the battery out of it, and short out the capacitor before removing the circuit:

Camerar

Chop off just that corner with the charging circuit on it :

Circuitsquare

Solder two pins and add four wires to make it usable :

Circuitwired

That's the difficult bit done.

The rest is plug and play. These are what you need :

Assemblym

The spark gap in this example is a 350V gas discharge tube (so it will arc at ~350V). You may also get by with an open air gap as commercial stun guns use which is two strips of metal crossing each other separated by a thin insulator.

To assemble follow the video:

It can be made smaller:

Tmpwu

I'm hoping to get it working with a solid state alternative to the gas discharge tubes such as a MOV or avalanche diode, anyone able to help out with advice in that respect?

Incidentally, although I use the tag of stungun, it has no relevance to its actual use. It was designed and made for flammable gas ignition. In potato guns.

Calling it a stun gun gets more hits than a high voltage spark generator though ^_^

Cheers.

EDIT: Images resized by moderator, read the rules about posting large images in post!

haxor5354

Sun Aug 07 2011, 04:17AM

Registered Member #2063 Joined: Sat Apr 04 2009, 03:16PM
Location: Toronto
Posts: 352

how long will the discharge tube live?

Hotwired

Sun Aug 07 2011, 04:25AM

Registered Member #4049 Joined: Sun Aug 07 2011, 03:50AM
Location: UK
Posts: 14

I've run this circuit flat out with two fresh AAA batteries for half an hour with no failure. Although as the batteries fade the spark rate does slow.

However the gas discharge tube does eventually fail, starts arcing at a much lower voltage and needs replacing. I can't really give a proper time period for that and doubtless neither can the manufacturer since normal use of these tubes is for surge protection not this lark.

Mind you while it does work it's an excellent and reliable switch for a set voltage.

klugesmith

Sun Aug 07 2011, 04:38AM

Registered Member #2099 Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1716

Nice demo.

Your pictures are much wider than the forum rules allow
(tho' we'be seen worse).
This is not a bandwidth thing, it's about readability on small
screens. If you use the "attach file" dialog, your post will
get a pretty large "thumbnail" image and clickable link to
the full size image.

Chip Fixes

Sun Aug 07 2011, 04:45AM

Registered Member #3781 Joined: Sat Mar 26 2011, 02:25AM
Location:
Posts: 701

have you shocked yourself with it yet? And how did you cut the PCB? I was just wondering

Hotwired

Sun Aug 07 2011, 04:53AM

Registered Member #4049 Joined: Sun Aug 07 2011, 03:50AM
Location: UK
Posts: 14

No and absolutely zero intention of finding out what a shock would be like, probably get quite a few jolts before a reflex could kick in.

The PCB was cut with a dremel using a thin cut off disk, much safer for the circuitry than waving a hacksaw at it.

kimbomba

Sun Aug 07 2011, 04:56AM

Registered Member #3854 Joined: Fri Apr 29 2011, 03:45AM
Location: Mexico
Posts: 95

Can you give more info on the HV coil construction please?

Hotwired

Sun Aug 07 2011, 05:02AM

Registered Member #4049 Joined: Sun Aug 07 2011, 03:50AM
Location: UK
Posts: 14

No I cannot.

Well I can, ish.

Ferrite core with the primary wrapped round that.

Secondary is wrapped on a plastic bobbin with 8 divisions over the ferrite core..

Whole thing is vacuum potted in epoxy.

The HV coil is not home made, it was hacked from a commercial spark generator which used a 9V and a solid state circuit to produce a spark for lighting a BBQ about twice a second.

The idea of the project was to make a driving circuit which could be added to any high voltage coil such as an ignition coil.

Conundrum

Sun Aug 07 2011, 08:00AM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4062

Hmm, I have some similar coils here which I bought online from some shady guy who claimed that they were out of "some sort of igniter"... needless to say I haven't had much luck getting them to work.
I didnt pay that much for them but maybe the problem was lack of voltage- the primary measured less than 1 ohm so can't have been that many turns.

I once made a homemade transformer using one of those electronic gas lighters with the coil and 1.5V AA, by potting the secondary in Araldite.
Even though air bubbles were present it did work and the output voltage before arcover was significantly higher than before.

The commercial transformers are made using a stack of iron laminations covered in fibreglass cladding, with the primary wound around that.
Over the top of the primary goes a second fibreglass cladding, followed by a plastic insert where the secondary coil is pile wound in sections.
Connections come out on opposite sides to reduce stress on the encapsulant, then the whole thing is heated to about 70C and soaked in mixed encapsulant which can be styrene monomer+catalyst, epoxy, etc.
Then the unit is placed under vacuum and ultrasound agitated to release any trapped bubbles within.

My thought is that CCFL transformers aren't that heavy so maybe someone can hack these into HV generators by replacing the primary with a new one wound at right angles to the secondary i.e. across the windings and then vacuum potting the transformer ?

Wonder if when combined with a high voltage diode and 30KV rated 1500pF capacitor (cheap, saw these on ebay for under Â£2 each) you could make a Lifter power supply?

-A

Alex M

Fri Aug 12 2011, 03:15PM

Registered Member #3943 Joined: Sun Jun 12 2011, 05:24PM
Location: The Shire, UK
Posts: 552

Awesome!

BTW what camera did you use?

1 2 3 next

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