Thanks Mike,

However I think that the op amp approach is more elegant and probably
cheaper to implement.

Ivan.

----- Original Message -----
From: "Michael Leavitt" <mike_c...@uswest.net>
To: <silver-list@eskimo.com>
Sent: Thursday, 27 July 2000 12:50
Subject: Re: CS>Away too long


> How about installing a potentiometer in series with the relay coil to
vary
> the available voltage, i.e. the point it would drop out. Take reading
of PPM
> and calibrate the scale of the knob on the pot.
>
> Mike
>
> Ivan Anderson wrote:
>
> > Maybe a voltage (or current) comparator opamp with a fet switch?
> > If any one nuts one out, please let me know.
> >
> > Ivan.
> >
> > ----- Original Message -----
> > From: "Robert L. Berger" <bober...@swbell.net>
> > To: <silver-list@eskimo.com>
> > Sent: Sunday, 16 July 2000 06:14
> > Subject: Re: CS>Away too long
> >
> > > Hi Erwin;
> > >
> > > I haven't found out how to program a relay with a selectable
window
> > for shut-off.
> > >
> > > Given me a schematic and I will paly with it.
> > >
> > > No doctor just a crotchy old guy'
> > >
> > > "Ole Bob"
> >
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