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From: Joe Riel <joer@san.rr.com>
Newsgroups: comp.soft-sys.math.maple
Subject: Re: Spice Question
Date: Sun, 31 Aug 2014 08:02:39 -0700
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"Thomas D. Dean" <tomdean@speakeasy.org> writes:

> On 08/30/14 17:15, Joe Riel wrote:
>
>>
>> As with any Spice deck, you need to assign ground (node 0).
>> Preferable is to change, say, node 1 to node 0.
>> Or add a short between 0 and 1.   Your subcircuit looks okay,
>> but I haven't tried it.
>>
>
> I forgot about node 0.
>
> Mostly, I was just looking into how Syrup would facilitate handling
> the original problem, which was stated to use FET's to switch a decade
> current measurement shunt in/out of the circuit.  The deck I used
> would be as if the FET from V to R1 had zero resistance.  The circuit
> would have 6 FET's, V to R1, V to R2, etc.
>
> "V 1 0 1\n\
> \n\
> sw1 1 13 sw1\n\
> R1a 13 out1 r_isol\n\
> R1 13 2\n\
> R1b 2 out2 r_isol\n\
> \n\
> sw2 1 23 sw1\n\
> R2a 23 out1 r_isol\n\
> R1 23 2\n\
> R2b 2 out2 r_isol\n\
> ... subckt 3 thru 6
> Rload 2 0 some_value
> ";
>
> The original problem had an opamp inputs connected out1 and out2.
>
> sw1, sw2, etc are the FET's. Some high R value and subs 0 for the one
> conducting?
>
> Not something I would want to build, I have a Fluke 87 and some 4
> terminal shunts...
>
> Thanks,
> Tom Dean

Do you have a link to a schematic? 

-- 
Joe Riel