Re: coil running of car battery(s)?

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Jim Lux" <jimlux@xxxxxxxxxxxxx>


----- Original Message -----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Sunday, January 23, 2005 12:00 PM
Subject: Re: coil running of car battery(s)?


> Original poster: Ed Phillips <evp@xxxxxxxxxxx>
>
> "I am thinking of doing somthing like this myself.this is what I am
> thinking
> of, a 555 timer ckt. @ around 60-100 hz driving a HEI auto coil (or 2).
> possably use the 555 ckt to drive a 3055 fet for more current to the
> coils?
> Use this for the HV power supply to the coil?
> don't know if this will work for sure but it sounds like it will. I will
> let you know if I get more information on this, what does every one else
> think?
> Jerry"
>
> The idea is generally OK but you'll certainly need a power transistor
> to drive the primary of the coil, preferably one with a lot higher
> voltage rating than the 3055.  I'm using an 800 volt IGBT for this
> purpose and it works fine.  Also, you'll want a buffer transistor
> between the 555 and the power transistor as otherwise the 555 may not
> last long.  I also use a capacitor in series with a resistor across the
> primary, with values determined experimentally.  Not too much help?
>
> As for the timer circuit, I have means for varying the width of the
> turnon pulse to the output transistor and the time between pulses.  The
> former sets the output voltage and there is a "saturation time" beyond
> which you don't get any more output but the current goes way up.  The
> timing between pulses varies the rep rate and hence the power input.


This is exactly what the ignition circuit does.  (also called, variously,
the ignition amplifier)...

Why reinvent the wheel.. the auto mfrs have spent a lot of time and money
making a really durable and reliable module that works over wide temperature
ranges in a harsh environment.


>