RE: Maximum input voltage for "can" style (Lucas/Bosch) ignition coil (fwd)

["High Voltage list" <hvlist@xxxxxxxxxx>]

Original poster: <sroys@xxxxxxxxxxxxxxxxx>



---------- Forwarded message ----------
Date: Wed, 17 Aug 2005 06:58:04 +1200
From: G. Tyler <gtyler@xxxxxxxxxxxxxxx>
To: 'High Voltage list' <hvlist@xxxxxxxxxx>
Subject: RE: Maximum input voltage for "can" style (Lucas/Bosch) ignition coil
    (fwd)

I designed a stun gun once, it is amazing what you get out of an ignition
type coil it you hit it with 1200V on the primary. It had a 1u capacitor
charged to about 1200V then a spark gap in series with a primary coil of
about 30T. Secondary was some hundreds of turns, the whole thing wound on a
ferrite rod 10mm dia about 40mm long. Found afterwards you could remove the
rod to make it air cored with no change in performance. It made a brilliant
blue spark 50mm long, even under water.

Regards
George 

-----Original Message-----
From: High Voltage list [mailto:hvlist@xxxxxxxxxx] 
Sent: Wednesday, 17 August 2005 3:20 a.m.
To: hvlist
Subject: Re: Maximum input voltage for "can" style (Lucas/Bosch) ignition
coil (fwd)

Original poster: <sroys@xxxxxxxxxxxxxxxxx>



---------- Forwarded message ----------
Date: Tue, 16 Aug 2005 16:07:31 +1200
From: Malcolm Watts <m.j.watts@xxxxxxxxxxxx>
To: High Voltage list <hvlist@xxxxxxxxxx>
Subject: Re: Maximum input voltage for "can" style (Lucas/Bosch) ignition
coil
    (fwd)

Hi Matthew,

On 15 Aug 2005, at 18:52, High Voltage list wrote:

> Original poster: <sroys@xxxxxxxxxxxxxxxxx>
>
>
>
> ---------- Forwarded message ----------
> Date: Sun, 14 Aug 2005 11:29:24 +0930
> From: Matthew Smith <matt@xxxxxxxxxx>
> To: High Voltage list <hvlist@xxxxxxxxxx>
> Subject: Maximum input voltage for "can" style (Lucas/Bosch) ignition
> coil
>
> Hi All
>
> Can anyone comment on what voltage can be put through the primary of
> an old canned (oil-filled) ignition coil without causing permanent
> damage?
>
> This would only be a pulse, non-repetitive.

You're unlikely to cause any damage to the primary coil. The
secondary might take a king hit if the output voltage isn't kept tio
a reasonable value by a suitable output gap. Then again it might not
work well at all. The ignition coil is basically a resonant device
and that means that the caps will have to withstand high amplitude
reversals, something they are not designed to do.

> I'm back on my Kodak photoflash solid-state Marx idea; caps are
> charged through diodes, solid-state relays will switch the caps into
> series. I'm proposing a test using four caps, at about 300V each.
>
> At 1200V, that's only 100 times the designed input voltage of the
> coil...
>
> The SSRs are all 240V (therefore capable of withstanding 340V DC),
> 10A.

Have you measured the primary inductance of the coil and calculated
the peak current that will be reached?

Malcolm

> And yes, this whole lot will be powered by a single 'AA' cell.  (The
> SSRs will be triggered by a 4.8V NiMH pack, but as it's just
> switching, I don't think that's cheating.)
>
> I'm no longer trying to kill snails (whacking them with a half-brick
> is doing the job fine) - I just want to see how big a spark I can get
> from an 'AA' cell...
>
> Cheers
>
> M
>
> --
> Matthew Smith
> Work: <http://www.kbc.net.au> | Home: <http://www.mss.cx>
>
> The time here is 11:20 and the temperature outside is 13.7°C; today's
> maximum is 15.7°C with a minimum of 10.6°C.  We have had 0.0mm of
> rain today, with a total of 12.6mm in the last week.  The wind is
> currently due ESE, gentle breeze, force 3 (11.4mph), gusting to
> moderate, force 4 (16.4mph).
>
>
>
>