Re: [Qucs-help] Strange behaviour on switch...

[Esteban L. <luc...@gm...>]

Hi,

First of all I have to correct myself because Vh should be half what I
said before, i.e. (Vpick-up+Vdrop-out)/2.

I attach a modified schematic.
I altered some things to my liking because my sight is failing :).
Notes:
1. I removed the 220 ohm resistor just because I didn't see its use
for what we're discussing.
2. Replacing a voltage probe to ground with a node label may make the
circuit easier to distinguish from the simulation-related things.
3. I placed two grounds so that there is no isolated circuit, because
simulators need a reference in each mesh.
4. I don't know the reason for the "DC analysis failed" warning. The
diagrams show what you might have been expecting.
5. I took the values for L1, R2 (and then SRC1) and S1, from the
datasheet of a NAIS SP2-DC24V relay, just because it was the first I
found.

Regards,
Esteban


On 9/25/15, Claudio Girardi <cla...@vi...> wrote:
> Hello Chris,
> Esteban is right, the relay in Qucs is an idealized model. It's true
> that in a real relay you have a (usually non-negligible) current that
> flows in the coil, but it is just a "parasitic" characteristic,
> ideally
> no current should be needed to control it.
> It' more or less similar for a transformer, the ideal one has
> infinite
> inductance, so no magnetizing current is present, but in practice the
> inductance is finite, so you have also that unwanted current in your
> component.
> Unfortunately the relay is not clearly documented, you can have a
> hint
> looking at its properties, the first one is "threshold voltage in
> Volts" and there are no characteristics related to current. We would
> like to have more documentation but only a few developers work on
> Qucs
> at present
> To make your circuit work, you can simply put in parallel the relay
> with the 220 ohm resistor, or put in parallel to the relay the
> equivalent resistance of the real relay it should represent (and
> modify
> its threshold voltage, if needed.
>
> Regards,
>   Claudio
>
>
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