Re: Convert 6 cyl tacho for use with 4 cyl

["TK" <terryk@foothill.net>]

The LM1819 is the ????4339 chip. Pins 5 and 8 are the loop gain. By cutting
the traces and adding a pot (start with a 50k ohm, you can scale the tach
for any application. Works on speedo's too.

Terry



----- Original Message -----
From: Scott Feaver <scott@j-body.com>
To: <gmecm@diy-efi.org>
Sent: Monday, May 22, 2000 4:06 PM
Subject: RE: Convert 6 cyl tacho for use with 4 cyl


> I changed a Tach for a 91 Sunbird from 4cyl to 6cyl.  All I ended up doing
> is changing the .047uF cap to a .033uF.  The circuit they use is almost
> exactly the circuit in the application notes for the LM1819 chip off of
> National Semiconductors website.
>
> Scott
>
> -----Original Message-----
> From: owner-gmecm@diy-efi.org [mailto:owner-gmecm@diy-efi.org]On Behalf
> Of Ludis Langens
> Sent: Monday, May 22, 2000 7:27 PM
> To: gmecm@diy-efi.org
> Subject: Re: Convert 6 cyl tacho for use with 4 cyl
>
>
> Shawn Lin wrote:
> >
> > In my '90 Grand Prix instrument cluster, the resistor is on the circuit
> > board very close to the terminals that the electro-mechanical motor
> > assembly plugs into.  The resistor is etched onto the back of a 14-pin
> > DIP which is white in color.  I can't remember, but I think the 14-pin
> > DIP has no function except as a surface for the resistor to be etched
> > upon.
>
> If the Grand Prix tach is like the other electronic GM tachs I've seen,
> it uses the LM1819 chip.  The "white 14-pin DIP" contains most of the
> resistors needed by that circuit.  The calibration resistor on the top
> layer is just one of them.
>
> --
> Ludis Langens                               ludis (at) cruzers (dot) com
> Mac, Fiero, & engine controller goodies:  http://www.cruzers.com/~ludis/
>
>
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