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Groups > comp.soft-sys.math.maple > #937

Re: Spice Question

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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

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Thread

Spice Question "Thomas D. Dean" <tomdean@speakeasy.org> - 2014-08-30 14:35 -0700
  Re: Spice Question Joe Riel <joer@san.rr.com> - 2014-08-30 17:15 -0700
    Re: Spice Question Joe Riel <joer@san.rr.com> - 2014-08-30 17:18 -0700
    Re: Spice Question "Thomas D. Dean" <tomdean@speakeasy.org> - 2014-08-30 23:44 -0700
      Re: Spice Question Joe Riel <joer@san.rr.com> - 2014-08-31 08:02 -0700
        Re: Spice Question "Thomas D. Dean" <tomdean@speakeasy.org> - 2014-09-01 21:22 -0700

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