Re: Would Snubbers Kill Ignition Coil Output? (fwd)

[Steven Roys <sroys@xxxxxxxx>]

---------- Forwarded message ----------
Date: Tue, 16 Dec 2003 08:16:12 -0700
From: robert & june heidlebaugh <rheidlebaugh@xxxxxxxxxxxxxx>
To: High Voltage list <hvlist@xxxxxxxxxx>
Subject: Re: Would Snubbers Kill Ignition Coil Output?

May I suggest shielding. I built an ignition system to replace a magneto
years passed and founed my system was triggered by close proxinity of
another engins spark plug firing. Get close to another engine and my system
would go nuts, what a mess.
   Robert   H
-- 


> From: "High Voltage list" <hvlist@xxxxxxxxxx>
> Date: Mon, 15 Dec 2003 19:54:34 -0700 (MST)
> To: <hvlist@xxxxxxxxxx>
> Subject: Re: Would Snubbers Kill Ignition Coil Output? (fwd)
> Resent-From: hvlist@xxxxxxxxxx
> Resent-Date: Mon, 15 Dec 2003 19:27:38 -0700
>
> Original poster: Steven Roys <sroys@xxxxxxxx>
>
>
>
> ---------- Forwarded message ----------
> Date: Mon, 15 Dec 2003 14:51:48 -0600
> From: Dr. Resonance <resonance@xxxxxxxxxx>
> To: High Voltage list <hvlist@xxxxxxxxxx>
> Subject: Re: Would Snubbers Kill Ignition Coil Output? (fwd)
>
>
> There is a special chip mfg by International Rectifier especially for this
> application.  It has all the snubbers necessary included in the chip.  It's
> made for driving ignition coils.  I've used it and it works great!
>
> It's a IGBT IR p/n IRGB14C40L.  Get the data sheets for these from IR.
> Rated 20 Amps continuous collector current.
>
> Dr. Resonance
>
> Resonance Research Corporation
> E11870 Shadylane Rd.
> Baraboo   WI   53913
>>
>> Thinking of putting electronic ignition on my aged Massey Ferguson
> tractor -
>> discretely of course, don't want to spoil the look of the thing.
>>
>> Just fiddling around with the components that I've got, I have some
> IRF748V
>> HEXFETS, which look ideal for the job of switching, having a TINY
> R{DS(on)}.
>>
>> Only problem is that they are only rated up to 60V.  This is fine for the
> sort
>> of voltages that I would expect to find around the tractor, but I'm rather
>> concerned about the magnitude of the back-EMF from the ignition coil.
>>
>> My thought would be to put in a snubber with RC in parallel in series with
> a
>> diode (I've got some nice hefty TO220-style SMPS diodes).
>>
>> However, would putting the snubber in kill the output of the coil and not
> leave
>> me enough to fire the plug?  My documentation is all SMPS stuff and
> doesn't
>> cover this type of core arrangement, so I'm not sure what's going on in
> there.
>> Does it act like a flyback with the mother and father of all airgaps?
>>
>> The idea was to have the points pulse a 555 in monostable mode, putting
> out a
>> 900ns pulse, driving the MOSFET via a totem-pole arrangement to speed up
> the
>> switching.  (The idea being to cut down losses and stop the thing getting
> too
>> darned hot.)
>>
>> Cheers
>>
>> M
>>
>>
>> --
>> Matthew Smith
>> Kadina Business Consultancy
>> South Australia
>> http://www.kbc.net.au
>>
>>
>>
>
>