LTspice current analysis or equation plotting

cmartinez

Joined Jan 17, 2007
8,218
Found it, the save device current was not ticked as is default. Works now except it's giving me negative amps. K thx, still playing with it.
Maybe you already know this, but if you hover the mouse above a component while pressing the <alt> key, it lets you plot the power (in watts) being dissipated by it.
 

Thread Starter

SamR

Joined Mar 19, 2019
5,031
I saw that, havn't tried it yet. Still trying to print to a file. I did a screen capture. Here is what I was wanting.

Capture.PNG
 

crutschow

Joined Mar 14, 2008
34,280
It must be giving me actual current instead of conventional current.
The positive direction of current in Spice is for conventional current, not electron flow.

But you have to check the orientation of a resistor, if plotting resistor current.
When you hover over the resistor, the arrow shows the direction of positive current flow.
If that doesn't give the desired polarity, just physically reverse the direction of the resistor.
 

Thread Starter

SamR

Joined Mar 19, 2019
5,031
I surmised the current flow from the negative values I got. However, I do not see an arrow when hovering over a resistor. Only the hand to change the value. Is there an arrow on the current probe? If so it is too small for me to see. I do not see as well as I did when younger. Ahh yes it is on the current probe. Thanks for the heads up.
 

Thread Starter

SamR

Joined Mar 19, 2019
5,031
OK, I reoriented the resistors and was able to eliminate the negative sign in front of the plot value. The battery still shows actual current flow from the cathode.
 

Thread Starter

SamR

Joined Mar 19, 2019
5,031
Thanks guys for all the help with LTspice. It is slowly coming together for me and I truly appreciate the recommendation to use it and all the help learning it.

Sam
 

cmartinez

Joined Jan 17, 2007
8,218
Thanks guys for all the help with LTspice. It is slowly coming together for me and I truly appreciate the recommendation to use it and all the help learning it.

Sam
The learning curve can be a little steep for some of us, but it's very much worth the effort. I've learned tons of things by just tweaking existing circuits and studying the results ... no real-life budget-burning short circuits and magic smoke required ... :)
 
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