[Diy_efi] schematic critique

[Mark Bowers & Family]

J,

My attachment exceeded your file size allocation. How now to do this? I do
not want to clog up the diy-efi server by posting as a genreal reply.......

Mark B.

----- Original Message -----
From: Toyota Supra <turbosupramk3 at hotmail.com>
To: <diy_efi at diy-efi.org>
Sent: Saturday, February 22, 2003 11:21 PM
Subject: Re: [Diy_efi] schematic critique


> hey mark!
>
> you should be able to email to this email address
>
> turbosupramk3 at hotmail.com , it can receive up to a meg if i remember
> correctly.
>
> thanks for taking the time out, i was just about to give up, as i built
the
> other circuit, and it does not work
>
> tty soon!
>
> -j
>
>
>
>
>
>
>
> >From: "Mark Bowers & Family" <mbalntel at cfw.com>
> >Reply-To: List for general do-it-yourself EFI talk <diy_efi at diy-efi.org>
> >To: "List for general do-it-yourself EFI talk" <diy_efi at diy-efi.org>
> >Subject: Re: [Diy_efi] schematic critique
> >Date: Fri, 21 Feb 2003 23:39:59 -0500
> >
> >J,
> >
> >I have finally gotten around to the schematic, drew it by hand, and have
> >scanned it for you, into a 750k .jpeg file; it a bit fuzzy, but readable.
> >Let me know where I can email this, and you can put it in your schematic
SW
> >and post.
> >
> >Items to note about this circuit:
> >1) Includes an input buffer resistor on the 12v supply to the 7808; this
> >prevents the input filter cap from trying to filter out all the noise on
> >the
> >car's 12v system, which will dry out the cap in short order and make it
> >useless
> >2) Adds filtering on the line from the fuel level sender, plus a slow
time
> >constant (several seconds) to smooth out any "wiggling" of the sender
> >output. The noise filter is important as you will ground the sender near
> >the
> >tank, and the gound for the control circuit may be in a different
location
> >in the car. If so, you will need a noise filter.
> >3) Feeds the fuel sender from the 8v bus; this will be a MUCH more stable
> >circuit, rather than feeding the sender form the car's 12v syste, If you
> >use
> >the 12v system to feed the sender, without running cvia the dash units
> >regulator, the switching point of the circuit will vary widely as the
car's
> >12v system voltage varies. (Hence why the put soem soret of regualtor in
> >the
> >dash!)
> >4) Implements the hystersis you wanted of approx 0.1v; you can increase
> >this
> >by DECREASING the 220k feedback resistor, within reason
> >5) Uses a simple NPN output driver
> >
> >Things to note:
> >a) Assumes that the fuel sender will present about 55 k ohms resistance
at
> >the point that you want the pump switched off; this can be changed by
> >varying the pot connected to pin 5.
> >b) The output drive transistor can support about 100mA max current, and
> >still be saturated. (Which means it will turned on hard, and there will
not
> >be much heating in the transistor.) This means your relay coil resistance
> >needs to be about 1200 to 1500 ohms. It is important that you measure
this.
> >If it is much lower, then the FET driver circuit that was espoused by one
> >fellow should be used.
> >c) Assumes that the fuel guage will NOT be connected to the sender; this
is
> >important.
> >
> >I took a quick look at the schematic 7 and I can't see it working at
first
> >glance; I lost the link so I can't look at it more..
> >
> >  And, my apologies for the long time to work on this; gotta work for a
> >livin' !
> >
> >Regards,
> >Mark B.
> >
> >
> >
> >
> >_______________________________________________
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> >Diy_efi at diy-efi.org
> >http://www.diy-efi.org/mailman/listinfo/diy_efi
>
>
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