At 11:22 1998-03-17 -0800, you wrote:
>The reason I want to use a V-F convertor for an amp-hour meter is
>- very simple, can use the lowest cost PIC
>- no need to come up with a fast sampling scheme (A/D convertor may not
>keep up)
>- more resolution, bigger dynamic range - just count the pulses
>- overall should prove to be more accurate since the voltage coming from
>the shunt will be continuously monitored.
>- easier to deal with RF noise coming from a DC-AC inverter also connected to
>the batteries.
>- pretty foolproof
>
I agree.
On top of my head, I think it is possible to brew a neat circuit of cheap
chips that uses switch technology to cancel OP ofset error, using cheap
CMOS4000-series MUX, and the PIC to drive it.  The core should be a
integrator driven by the differential voltage across measuring R, and the
operaton should be that the PIC tries to keep the integrator at zero by
adding pulses of known current to integrator.  I will tell no more...  ;)
/Morgan
/  Morgan Olsson, MORGANS REGLERTEKNIK, SE-277 35 KIVIK, Sweden \
\  mrt@iname.com, ph: +46 (0)414 70741; fax +46 (0)414 70331    /