[Diy_efi] LM1949 peak-hold driver chip , bank fire 4 injectors?

[Keith Ballantyne]

I still think the darlington is the best solution to that problem

Keith Ballantyne


> -----Original Message-----
> From: Les Dittert [mailto:lesd at earthlink.net]
> Sent: Wednesday, September 11, 2002 9:55 PM
> To: diy_efi at diy-efi.org
> Subject: RE: [Diy_efi] LM1949 peak-hold driver chip , bank fire 4
> injectors?
>=20
> Thanks Tim,
> I guess I'll just make 4 drivers, and for now feed them off the same
> pulse.
> Do you know if I can substitute a mosfet for the Darlington, perhaps
> using the
> switching mode of the lm1949.
> I wish someone had a little driver pc board with these on there. What
> are people
> doing to drive modern injectors these days, other than this method?
>=20
> -Les
>=20
>=20
> -----Original Message-----
> From: diy_efi-admin at diy-efi.org [mailto:diy_efi-admin at diy-efi.org] On
> Behalf Of Van Setten, Tim @ ACSSD
> Sent: Wednesday, September 11, 2002 6:12 AM
> To: 'diy_efi at diy-efi.org'
> Subject: RE: [Diy_efi] LM1949 peak-hold driver chip , bank fire 4
> injectors?
>=20
>=20
> > The national LM1949 is made to drive a transistor to fire an
> > injector peak and hold style. Can someone tell me to tell me if
> > it's possible to use this with a bank firing of 4  injectors?
> > My concern is the selection of the proper transistor (can it be a
> > mosfet)
> > and also the overloading of the zenor diode, since it's getting back
> > current
> >  from 4 injectors instead of one.
> >
> 	The problem here is that injectors are inductors, and inductors
> in parallel don't like to share current.  I know you see setups all
the
> time and in various wiring diagrams, but the correct way to wire low
> impedance or peak-and-hold style injectors in parallel is to put a
> resistor is series with each one.  A value of 1 to 2.2 Ohms should
> correct this current sharing problem with injectors.
>=20
> 	The LM1949 IC is intended to run only one injector, however, the
> current sense resistor can be changed to alter your "Peak" current
> level. Hope this helps.....Tim.
>=20
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>=20
>=20
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