Igniters => DIS

[Bob Wooten]

thanks for the input.  have you (or anyone on the list) used the IGBT for
igniters?  from what I can see of their usage (& the spec sheet), they can
be put into an application where you would normally use a smart igniter but
you don't have to worry about current limiting or them overheating (or the
kickback but you would expect that).  am I missing something or does the
same apply & I would smoke it if you hold it on for too long?

I have been working on my little DIS project & am counting on the coil
charging for a maximum of 3/4 of a rev of the crank.  this being the case @
idle the circuit would have the longest "on" time @ 23.1 mS @ 650 RPM, & the
shortest time of 1.5 mS @ 10K RPM (yea like my stroker is going to get to
10K, God I hope not or I will put small bits of stroker all over the road).
think that this would be too long @ idle?  I am going to mock it up with
LED's @ first & the plug the coils in later & see what happens.

I have an updated print with more notes & pinouts if anyone is interested.

if this does happen to be too long a charge time then maybe I will give
James a ring & see if I cant get some of those smart igniters from him &
skip the IGBT all together.  I would much rather pay the $4 each than $30
each for igniters though.  specially if I goto CNP ($30 X 8 = too much)

thanks to all
BW

ps using outlook now so should be no junk in the archives but what I type.





-----Original Message-----
From: owner-diy_efi at diy-efi.org [mailto:owner-diy_efi at diy-efi.org]On
Behalf Of Dan Zorde
Sent: Tuesday, February 27, 2001 4:25 PM
To: diy_efi at diy-efi.org
Subject: Re: Ignitors



My understanding exactly.  Its a little bit more involved than a simple RC
circuit but as a basic answer its spot on.  The slightly more involved
answer is that there is over voltage protection, kick back protection,
controlled current charging, TTL signal control capability, etc.  Whereas a
dumb ignitior is effectively just a big transistor (or MOSFET) you switch
on to charge the coil, hence the on time (coil charge time) needs to be
controlled from elsewhere or it will smoke.  Your aftermarket transistor
assisted ignition system is an example of a smart ignitor, it only uses the
points as a trigger while all coil charge time and firing is controlled
independently by the electronics.

On your email program, you could download Eudora or Pegasus, both freely
available if you search for them, I have found that both work quite well.

Dan  dzorde at erggroup.com


>Date: Mon, 26 Feb 2001 21:8:54 -0800
>From: "Bob Wooten" <r71chevy at earthlink.net>
>Subject: Ignitors
>
>Pardon the ignorance here but i want to see if i can not clear something
up
>(in my head I'm sure).  simply stated is an ignitor a coil driver?  is
this
>the device that takes the low current triggering signal & drives the high
>current primary side of the coil?
>
>if this is the case then by smart ignitor that means that the driver has
>some type of timing circuit in it & after XXX uSeconds it will
>automatically change states on the driver.  if this is true then it would
>follow that this would probably just be  simple RC time constant that
holds
>the charge @ the "gate" to the driver & then when it bleeds down to some
>threshold it changes the state of the driver (in uSeconds i would
imagine)?
>
>the not so obvious reason for using a smart ignitor VS a "dumb" one would
>be that if it did not auto fire that the constant current going though the
>ignitor for a "long" period of time (long being a relative term here)
might
>overheat it & cause the smoke to be let out of it.
>
>
>
>- --- Bob Wooten
>- --- r71chevy at earthlink.net
>- --- www.r71camaro.homestead.com
>
>
>PS am going to have to change email programs to get rid of the HTML thing.
>i have outlook on this machine, but not in use.  any thoughts?



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