Use a xtr110 ic
it does everything for you
I forgot who makes them
Justin Grimm    reaper@southwest.com.au


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> From: Chris Eddy <ceddy@NB.NET>
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: [OT] 4-20ma to 0-10V Sensor questions
> Date: Thursday, 16 April 1998 2:01
>
> Mike..
> The standard is usually 4-20mA, with an ocasional rebel using 0-20mA.
> The circuit that I use is relatively simple, but too complex to draw
> here.  If you like, Email your fax number and I'll fax a sketch.  Note
> that there are two variations, a source and a sink.  The source version
> generates the current into a load that returns to ground.  The sink
> pulls current to ground, but requires that the load be connected to a
> high side + voltage.  Which do you require?  A simple circuit can be
> generated if you do not need to adjust zero and span, but if you do,
> there is a circuit that has pots in the apropriate places.  Last but not
> least, there are circuits by Analog Devices, Burr Brown, and others that
> do it for you.  They are sometimes quite pricey.
>
>
> Chris Eddy, PE
>
> Montaigne, Mike wrote:
>
> > The defacto standard input on Omega & other sensors seems to be
> > 2-20ma with an internal impedance of about 1K.  Does anyone
> > have a simple circuit to convert 0-5 volts from an PIC, or
> > 0-10 volts from an external A-D on a PC which we are using now
> > to this 2-20ma standard?  tks
> >
> > Mike Montaigne
> > Atomic Energy of Canada Ltd.
> > Station 18, Chalk River, Ontario
> > K0J 1J0, Canada
> >
> > Phone (613) 584-3311 Ex. 4005
> > Fax:     (613) 584-4040
> > email:   montaignem@aecl.ca
>
>
>