A single throw, single pole, voltage controlled switch is easy enough for me to understand since LTSpice provides for it in its library of lots of extra components. But I don't understand how to stretch this to become a double throw switch, nor how to construct it from scratch?

 

EM, what' the reason for both V1 and V2 control signals?
You just need one.

 

EM, what' the reason for both V1 and V2 control signals?
You just need one.

V2 is a 1 volt supply which pulls S1+ up to 1V so that when V1 goes low S1 will switch.

I neglected to show "SW" on the earlier schematic, but I fixed it in post #4.
Sorry about any confusion...

 

A single throw, single pole, voltage controlled switch is easy enough for me to understand since LTSpice provides for it in its library of lots of extra components. But I don't understand how to stretch this to become a double throw switch, nor how to construct it from scratch?

 

Here are the two switches configured for SPDT using a single control line:
Using opposite input control polarities on the two switches and, with appropriate switching threshold, alternates their operation.

 

Here are the two switches configured for SPDT using a single control line:
Using opposite input control polarities on the two switches and, with appropriate switching threshold, alternates their operation.

View attachment 127585

Seems like a lot of hoops to jump through just to avoid a simple DC supply.

 

Seems like a lot of hoops to jump through just to avoid a simple DC supply.

Really?
What hoops?
You just reverse the control connection to one of the switches.
To me, adding another supply adds unnecessary part and wire complexity to the schematic.
But to each his own.

 

Really?
What hoops?
You just reverse the control connection to one of the switches.

AND use a control signal which switches from positive to negative, AND bias the relays' thresholds so they sit at what's required to get them to work with the +/- drive.

To me, adding another supply adds unnecessary part and wire complexity to the schematic.

To me, there's really no added supply since, in the real world, there'll be a supply there anyway unless, perhaps you're driving the relays with an isolated function generator or suchlike.

But to each his own.

Indeed.

 

Well, I can certainly see that your criteria for what qualifies as a hoop is quite different from mine.

 

Thanks, guys, for all of your help. Now, I have the leisure to apply it and see how well either method works.

 

View attachment 127583

How do I stack waveforms?
And my output seems a bit empty?
Thanks for your help.

 

How do I stack waveforms?

Click on the waveform window.
Click on plot settings.
Click on Add Plot Plane.

And my output seems a bit empty?

EM didn't show the generator source settings for some reason.
Right click on V1
Add this:

Right click V2
Add this:

 

Click on the waveform window.
Click on plot settings.
Click on Add Plot Plane.
EM didn't show the generator source settings for some reason.
Right click on V1
Add this:
View attachment 127856
Right click V2
Add this:
View attachment 127855

Way, cool! Thanks!


I'm curious what do 'C', 'NO' and 'NC' mean?



Thanks for your help!

 

Way, cool! Thanks!
View attachment 127859

I'm curious what do 'C', 'NO' and 'NC' mean?

C = Common
NO = Normally Closed
NC = Normally Open

View attachment 127860

Thanks for your help!