Re: gEDA-user: Transformer refdes assigned to relay

[Stuart Brorson <sdb@xxxxxxxxxx>]

On Fri, 7 Sep 2007, Robert Butts wrote:

> After I auto-numbered a schematic with a dpdt omron relay the relay has a
> refdes starting with the letter k.  Is there a way for me to configure
> gschem so that relays are numbered with the correct letter?  And, am I right
> in assuming that should be the letter "s"?

Naw, I've seen K frequntly used as the refdes for relays.  I do think
the refdes used isn't as standardized (though convendtion) as, say, R
for resistor.

It sounds like somebody has put the refdes designation K? in the
symbol itself.  If you want to change it, either edit the symbol using
the symbol editor mode in gschem, or just edit the symbol text file
using a text editor.

> While I'm asking this question I'd like to ask one more.  When I tried to
> simulate this circuit in Ltspice I had the following errors:
>
> mutual inductance card missing coupled inductor: k1 3 4 1 5
> unconnected_pin-3 unconnected_pin-1 unconnected_pin-2 0 <no valid value
> attribute found>
>
> I take it it's a problem if you don't use every pin of every slot?  How can
> I correct this?  And, I'm sorry that was actually two questions!

No, the problem is that SPICE thinks K is a coupled inductor pair
(transformer), and wants to see a coupling coefficient attribute.
Read about it here:

http://www.seas.upenn.edu/~jan/spice/spice.mutualInductor.html

Ummmm, is there any reason you are trying to SPICE simulate a circuit
with a relay in it?  SPICE doesn't have exactly the concept of a
relay, and won't know what to do with it when trying to simulate.

SPICE thinks that an S refdes is a voltage controlled switch:

http://www.seas.upenn.edu/~jan/spice/spice.overview.html#Switches

and it might do the right thing in your circuit, depending upon how
you set up the corresponding switch model, and maybe depending upon
how important it is that the relay's input is an inductor as opposed
to an open circuit.

Stuart


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