At 01:20 AM 5/6/98 EDT, you wrote:
>Hello everyone
>
>I want to drive the OEM fuel gauge used on most common vehicles. Current
>gauges use a resistive device to ground to drive the gauge, for example most
>Chevy use a 0-90 ohm sender ( 0=full, 90=empty) , Ford 160-10 or 70-0 ohm and
>a few others.How can I use a stamp or PIC to drive these gauges. I was
>wondering if I could use PWM to drive the gauge to ground? I could utilize a
>different table for each vehicle type. Any suggestions on how I might
>accomplish this. Feel free to offer other suggestions I don't know if PWM
will
>work, but I am sure someone out there has figured out a slick way to do this.

Jon,
   These gages really measure current so OHM's Law applies

        I = E/R where I=Current in Amps
        E = Voltage in Volts
        R = Resistance in ohms.

The applied voltage is 12 VDC, and the resistance consists
of the resistance of the meter + the variable resistance of
the gage.  I have never measured the current through the gages
so I don't know first hand if the PIC can drive the Meter to full
scale or not.

Assuming the PIC can handle the current then it is a simple matter of
setting the pic output to a voltage level which gives the
desired reading.  No need for PWM.  My gut feeling is that you
will need to use an emitter follower circuit inplace of the
gage & drive that with the PIC analog output voltage

-Dan
kf6izo@qsl.net

>
>         Gauge----------------Sender-----------GND
>
>Thanks in advance
>
>Jon
>
>