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How can I use the Volt Meter to plot Voltage?

When I click on a Volt Meter it is not added to the list of lines to plot.

I must be doing something wrong :-)

Thanks Eldon

I'm not sure quite what the Voltmeter and Ammeter symbols are for, other than as familiar symbols.

Personally, I don't use them as they clutter up circuit diagrams unnecessarily.

To get a voltage measurement from the voltmeter you hover over the ends of the symbol (+ or - depending on the polarity you want to measure) until the little grey circle appears. Then click on the circle.

This will add a voltage and a current to your simulation plot expressions list.

The same thing applies to the Ammeter symbol.

However, you don't actually need these symbols because if you want to measure a voltage, either hover the mouse over any component end and click on the little grey circle or add a net netame to the net you want to measure and click on that.

As long as the node you click on has a single wire in and out, i.e. no branches, then the same action as for a voltage will automatically add a current measurement. It will also add a voltage measurement.

If the node has branches, then insert a DC voltage source, set to 0V, in series with the net in which you want to measure the current then click on the grey circle at the relevant end of the 0V DC source. This will add the voltage and current measurements for a single net and node respectively.

Does that make sense?

Yes, . . it makes sense.

What I was attempting to do was measure and plot the differential voltage between to points. I know that I can attach label tags and a Function (i.e., V(one) - V(two) ) to plot the value. Also, I know how to get the Node Name for arbitrary points in the circuit - but it is a lot of typing and remembering (when a simple click would do), and their names change as the circuit is changed.

But I guess I was hoping that the Voltmeter would do this for me, similar to plotting any voltage (ref to ground) at any label tag.

Perhaps a single click on the Voltmeter could be a Differential Plot Enhancement? hint, Hint!

Thanks, Eldon

Attaching net names stops them changing as the circuit changes and makes interpreting plot traces easier.

However, there's a down side to manually assigning net names: you have to have a very good memory to avoid accidentally giving two nets the same name and so causing accidental cross connections.

A common mistake is to copy and paste a block of circuitry a net but then forget to change the net names in the copied block.

Automatic netnaming means that no two separate nets ever end up with the same name.

Maybe we should post feature requests:

A more user friendly Voltmeter and Ammeter functionality

Automatic net renaming when copying blocks with manually assigned netnames (add a number or may be a symbol and a number after the existing name?).

heh... Many moons ago I was a civil engineer. When you do a sewer or storm drain design, the manholes are numbered. The numbering system goes from the bottom most (MH0), and works up (MH1...n). When you have two converging streams you take the MH number, multiply it by 10, and add 1. For example, if you have an incoming pipe into manhole 3, now suddenly the upstream pipes are manhole 30 and 31. This way it's practically impossible to have two manholes with the same number.

I've tried to stick to this with my node ID's with circuits. The numbers grow, but they make sense.

I use GNU spice for my final drawings. I've started using circuit lab as an intermediate between a full blown spice simulator and Paul Faulstad's circuit simulator, which I use more as a sketch book. http://www./circuit/