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My circuit

I faced some errors while trying to simulate a circuit. I tried to simplify it, but errors still stayed in place :|

The following error message is what I get:

                    *************** PROCESS COMMAND ***************

/usr/bin/ngspice -n -b /home/rasakereh/Desktop/sharif/9602/EEC/test/test.ckt

                *************** PROCESS RESPONSE **************

Warning: singular matrix:  check nodes v3#branch and v3#branch

Warning: singular matrix:  check nodes v3#branch and v3#branch

Note: Starting dynamic gmin stepping
Trying gmin =   1.0000E-03 Warning: singular matrix:  check nodes v3#branch and v3#branch

Warning: Further gmin increment
Trying gmin =   5.6234E-03 Warning: singular matrix:  check nodes v3#branch and v3#branch

Warning: Further gmin increment
Trying gmin =   8.6596E-03 Warning: singular matrix:  check nodes v3#branch and v3#branch

...

Warning: gmin step failed
Warning: source stepping failed
doAnalyses: iteration limit reached

run simulation(s) aborted
Error: no such vector v(4)

Circuit: ********************************************************************************

Doing analysis at TEMP = 27.000000 and TNOM = 27.000000


CPU time since last call: 0.009 seconds.

Total CPU time: 0.010 seconds.

Total DRAM available = 7880.691406 MB.
DRAM currently available = 4678.652344 MB.
Total ngspice program size = 14.774414 MB.
Resident set size = 1.865234 MB.
Shared ngspice pages = 1.638672 MB.
Text (code) pages = 1.333008 MB.
Stack = 0 bytes.
Library pages = 404.000 kB.

I am using gEDA gscheme to generate the schematic, netlisting it using gnetlist and spice-sdb backend, trying to simulate it in gSpiceUi.

Thanks

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  • 2
    \$\begingroup\$ What do you think the voltage at the top node should be, 23 V or 63 V? \$\endgroup\$
    – The Photon
    Commented Mar 15, 2018 at 21:36
  • \$\begingroup\$ wow .... those power supplies would really smoke if they were real \$\endgroup\$
    – jsotola
    Commented Mar 15, 2018 at 22:44
  • \$\begingroup\$ note: the orientation of V2 and V4 shows a lack of attention to detail and to neatness. \$\endgroup\$
    – jsotola
    Commented Mar 15, 2018 at 22:45
  • \$\begingroup\$ @ThePhoton: you are right :)) \$\endgroup\$ Commented Mar 16, 2018 at 6:08
  • \$\begingroup\$ @jsotola smoke :D \$\endgroup\$ Commented Mar 16, 2018 at 6:08

3 Answers 3

4
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You have voltage sources connected in a loop. That can't work.

Add some series resistance or change the circuit.

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  • \$\begingroup\$ In fact, the main circuit had dependent voltage sources (CCVS) instead of V2 and V4. Would it force the controller currents to have specific values? \$\endgroup\$ Commented Mar 16, 2018 at 6:39
  • \$\begingroup\$ No it can't force the inputs like that. It may even fail with two exactly equal voltage sources in parallel if there is no resistance in the circuit. \$\endgroup\$ Commented Mar 16, 2018 at 8:38
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In general, a 'singular matrix' error means you either have

a) A loop of zero impedance elements (for instance inductors, voltage sources)

b) An infinite impedance node (for instance a series connection of two capacitors)

In both cases, judicious use of a small resistor to put some impedance in the loop, which is probably realistic anyway, or a big resistor from the node to ground (10meg, 100meg) will make the simulator maths happy without changing the operation of your circuit too much.

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You are probably missing a 0 node that denotes GND (zero potential reference point). That was my case when simulating in KiCAD [1] :-)

[1] https://kicad.org/

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  • \$\begingroup\$ That was it for me. I wonder why the software can't detect this automatically and output a warning... seems simple enough. \$\endgroup\$
    – smheidrich
    Commented Dec 23, 2021 at 18:53
  • \$\begingroup\$ Same. When I exported a circuit from KiCAD it failed to include a ground / 0 reference. \$\endgroup\$
    – bathMarm0t
    Commented Apr 5, 2022 at 21:34

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