Simple CMOS Schmitt simulation

[Terry Pinnell]

Can anyone see why this simple CMOS Schmitt does not simulate reliably
please?

http://www.terrypin.dial.pipex.com/Images/Schmitt-NoSIM.gif

For CircuitMaker users, here's the circuit:
http://www.terrypin.dial.pipex.com/Images/Schmitt-NoSIM.CKT

I don't even get an error message. But the input signal, which should
be several cycles of a triangular wave, just stops abruptly. Yet, if I
replace the generator with a direct connection to either 0V or 5V, I
get the correct simulated output (0V or 5V respectively).

It seems the value of R1 is critical. When I lowered that to 519k, the
circuit simulated correctly. At 520k it failed!

Any insight as to the underlying cause please?

--
Terry Pinnell
Hobbyist, West Sussex, UK

 

[Fred Bartoli]

"Terry Pinnell" <terrypinDELETE@THESEdial.pipex.com> a écrit dans le message
de news:9e7gr09ik90v6ccrhof7h8itrhmqkhcqet@4ax.com...

For CircuitMaker users, here's the circuit:
http://www.terrypin.dial.pipex.com/Images/Schmitt-NoSIM.CKT

snip
Any insight as to the underlying cause please?

Terry,

the CKT file format is CM proprietary and almost unintelligible.
Please post a spice netlist (.cir file) and also the NOR subckt in case they
are not included in the .cir file.


--
Thanks,
Fred.

 

[Terry Pinnell]

"Fred Bartoli"
<fred._canxxxel_this_bartoli@RemoveThatAlso_free.fr_AndThisToo> wrote:

"Terry Pinnell" <terrypinDELETE@THESEdial.pipex.com> a écrit dans le message
de news:9e7gr09ik90v6ccrhof7h8itrhmqkhcqet@4ax.com...
For CircuitMaker users, here's the circuit:
http://www.terrypin.dial.pipex.com/Images/Schmitt-NoSIM.CKT

snip
Any insight as to the underlying cause please?

Terry,
the CKT file format is CM proprietary and almost unintelligible.
Please post a spice netlist (.cir file) and also the NOR subckt in case they
are not included in the .cir file.

OK, thanks Fred, here's the netlist
http://www.terrypin.dial.pipex.com/Images/Schmitt-NoSIM.NET

But in CM it's trivially easy to just place and connect the 2 NORs, 2
Rs and the source. I'd assumed that's what a non-CM user might do to
see if the same simulation issue arises?

--
Terry Pinnell
Hobbyist, West Sussex, UK