Power probe (Spice)

[Hildo Guillardi Júnior]

For use to graphical simulator (Spice) will be nice have have current probe (placed on the wires, on one direction), voltage probes (placed on the nodes) and power probes (placed on the components).
To power probes, use the `p = sum( v(pin) * i(pin)). Because current and voltage have signal, the total of this sum is the power in a component. It will be very useful to transistors simulation.

Example in other EDA:
https://www.youtube.com/watch?v=1VHQaBZwDN8
https://www.youtube.com/watch?v=54h_OHqrerQ (current)

Interesting also the name be editable to some user friendly like "in" / "out" ... not just the default names "V(R1)" ...

[Hildo Guillardi Júnior (hildogjr)]

https://www.youtube.com/watch?v=MfQP_CK1Geg
To exemplify the power probe, not not like this video, but using as the videos before to plot in the graph results.
The point here: the power probe have to placed on the component.

[Urs Obernolte (urs-obernolte)]

I would really appreciate the current probe in the near future if the power probe is more complicated to implement.
Maybe also a good thing would be a possibility to type in formulas to display like the power probe mentioned in the bug report/feature request. That could be done in the "Add Signals" window (like Cadence PSpice)

[Hildo Guillardi Júnior (hildogjr)]

The power probe could be implement as "sum of each pin voltage multiplied by the current fluxing to inside".
As exemplo a resistor:
            ____
i1-> (1)---|____|---(2) <- i2

Puting the proble at the component:
p_resistor = v1*i1 + v2*i2 ...

This topology should deal with all analog models.

@Urs, yes, formulas should be very nice (allowing add multiplication between measured signals of by constants... also RMS and mean values).

[Urs Obernolte (urs-obernolte)]

In Addition to the Placements of the current probes, I think, due to the nature of spice, they can only be placed on the component pins, but that's what I have expected.

[Hildo Guillardi Júnior (hildogjr)]

Yes @Urs, usually yes.

But my experience with new designed Spice simulators (Proteus and MultiSim): it's allowed to the voltage and current probe to be placed along the wire. The current probe have a arrow that identify the direction, the software (maybe in the user layer) translate to the current going in/out some pin.
https://www.youtube.com/watch?v=54h_OHqrerQ&t=1m41s
https://www.youtube.com/watch?v=5AbkoXTsx_w&t=55s
https://www.youtube.com/watch?v=nwEBYM27UQQ&t=9s

I known that all this option is based on other EDAs, but I think could provide the better UX.

The power propose, is mine, I never saw. But is how I manually implement at the software that I already used through block and measurements.

The power probe should be placed at the component and the voltage/current at any wire.

[Jeff Young (jeyjey)]

Current probe has been implemented.

[KiCad Janitor (kicad-janitor)]

Fixed in revision a96158e26bf975f6cd068239b42ca10e5bd0fcba
https://git.launchpad.net/kicad/patch/?id=a96158e26bf975f6cd068239b42ca10e5bd0fcba

[Hildo Guillardi Júnior (hildogjr)]

I saw that was codded some icons:
1. Current probe: should be placed at the wire with the correct direction
2. Power probe: should be placed at the part/component
3. Voltage probe: should be place at wires
4. Differential voltage probe (same as 3 with additional in the label): should be place in two part, the first click to the (+) (positive, labeled as the `name_string+'(+)'`) and the second click to place the (-) (negative, labeled as the `name_string+'(+)'`)

[Jeff Young (jeyjey)]

@Hildo, that's another way to do it, but then you need 3 tools. I much prefer LTSpice's method of switching automatically to the current probe over pins.

I also assume LTSpice has the lions-share of the market. (Is that correct?)

Any other opinions?

[Michael Kavanagh (michaelkavanagh)]

I prefer the LTspice-like behaviour, and I think most people will expect it because of the LTspice market share.

FYI the current probe on some two pin devices (e.g. R's and C's, not V-source) highlights the opposite pin to the one being hovered over.

[Wayne Stambaugh (stambaughw)]

+1 for the LTSpice behavior.

[Seth Hillbrand (sethh)]

I _never_ thought I'd say this but I like LTSpice's user interface here. :)

+1

[Hildo Guillardi Júnior (hildogjr)]

May be a opinion, and I never used LTSpice. Which appear to allow the use of current/voltage probes only in the components pins.
https://www.youtube.com/watch?v=6QzTZDm0guM
(I was trying to in install and give a ride but LTSpice is'not a Linux software...)

I just used PSpice, OrCad, EWB, MultiSim, Tina (from TI) and Proteus. Between them I like the Proteus voltage/current probe behavior (also used in MultSim) that allow the use in both: pins and wires.
https://www.youtube.com/watch?v=54h_OHqrerQ&t=1m38s
https://www.youtube.com/watch?v=sA7T4t5pWTw&t=2m52s

The current probe have an arrow that indicate the measurement direction (if you flip it, the graphic will invert).
Initially the probe is named by the most closed (in wire length) pin.
To create this 2 behaviors above it necessary some function in KiCad to measure the lengths of a pont to all connections and something to translate the direction as +/-. But I think this represent better the measure procedure in an experimental perspective.

[Hildo Guillardi Júnior (hildogjr)]

Allowing the probes to be attached to the wires (not just in pins) allow to measure the situation attached (check the red arrow).

[KiCad Janitor (kicad-janitor)]

KiCad bug tracker has moved to Gitlab. This report is now available here: https://gitlab.com/kicad/code/kicad/-/issues/2091