Re: Fattening-up an HT spark
- From: John Larkin <jjlarkin@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
- Date: Sat, 26 Nov 2005 18:49:12 -0800
On 26 Nov 2005 17:45:41 -0800, bill.sloman@xxxxxxxx wrote:
>
>Jim Thompson wrote:
>> On Sat, 26 Nov 2005 19:03:02 -0500, Boris Mohar
>> <borism_-void-_@xxxxxxxxxxxx> wrote:
>>
>> >On Sat, 26 Nov 2005 19:17:45 +0100, Paul Burridge
>> ><pb@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>> >
>> >>The electronic ignition system I've been developing (just for a bit of
>> >>excitement) is firing up in a timely fashion; the only downer is the
>> >>spark's a bit on the weak side. Is there any way of fattening-up a
>> >>spark from an HT coil driven by a switching IGFET so it's nice and
>> >>chubby and blue rather than skinny and sort of yellowish? I've got
>> >>some half-remembered concept about using a capacitor in series with
>> >>the coil that resonates with it in a Teslaesque fashion, but am
>> >>stumbling about in the dark here, quite frankly. Any suggestions,
>> >>chaps?
>> >>p.
>> >
>> > Like this? http://www.viatrack.ca/Misc/PLASMA.JPG
>> >
>> >The plug fires via a conventional ignition coil. Connected to it is a diode,
>> >inductor and a 10uF capacitor charged to about 600V The diode must hold off
>> >the HV from the ignition coil and carry the current from the capacitor. The
>> >inductor limits the current. The spark plug must not have a resistor inside.
>> >The picture is a photograph of a single shot. The gap wear is significant. I
>> >have not tried fancy electrode materials.
>> >
>> >
>> >
>> >
>> >Regards,
>> >
>> >Boris Mohar
>> >
>>
>> Cripes! 1.8 Joules, as opposed to typical 65mJ... but a 65mJ CD
>> ignition WILL make a juicy spark... just not a plasma (which is why
>> your "gap wear is significant" ;-)
>
>Back around 1970, a bunch of us made our own CDI systems, all slightly
>different, and it turned out that 250V and IuF (31.2.5mJ) or 300V and
>0.47uF (21mJ) didn't erode our spark plugs, while 300V and 1uF (45mJ)
>did.
>
I ran about 80 mJ on my motorcycle CD's, but the bikes got wrecked or
stolen often enough that plug wear wasn't a big issue.
John
.
- References:
- Fattening-up an HT spark
- From: Paul Burridge
- Re: Fattening-up an HT spark
- From: Boris Mohar
- Re: Fattening-up an HT spark
- From: Jim Thompson
- Re: Fattening-up an HT spark
- From: bill . sloman
- Fattening-up an HT spark
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