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

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Original poster: <sroys@xxxxxxxxxxxxxxxxx>



---------- Forwarded message ----------
Date: Wed, 17 Aug 2005 07:46:00 +0930
From: Matthew Smith <matt@xxxxxxxxxx>
To: hvlist@xxxxxxxxxx
Subject: Re: Maximum input voltage for "can" style (Lucas/Bosch) ignition coil

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

I know how to calculate the reactance of an inductor in an AC circuit,
but have to confess that I wouldn't know how to do this.

Would you care to share the formula?

Malcolm:
"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."

No, they are not!  To avoid electrolytic pyrotechnics, maybe I should
have some sort of (large) diode/resistor arrangement between across the
output of the capacitor bank to sink anything nasty coming back at me.
Something like:

...--+----|>|----+------+
     |     D     |      |
    ___          >      )
    ___ C        <      )
     |           > R    ) L
     |           |      )
     |          ___     |
     |           ^ D    |
     |           |      |
...--+-----------+------+

...where C is the last capacitor and L is the primary of the coil.

Cheers

M

-- 
Matthew Smith
South Australia
http://www.kbc.net.au