Can I change voltage source type in an existing schematic without deleting and replacing?

QSPICE
1

For example, I want to convert the DC voltage to a sinusoidal voltage.
In LTspice, a right-click and selection of “advanced” is all it takes to adjust the properties of the voltage source as desired.

2

Okay, I’ve discovered that in the schematic, you can double-click the attribute line next to the voltage source symbol. There, you can modify parameters such as the voltage source type, offset, or frequency (while paying attention to the syntax helper line directly below the actual input field). For an LTspice user, this is somewhat unfamiliar and a bit cumbersome…

3

Mike intentionally removed the right-click pop-up window (Classic GUI Interface Feature - QSPICE - Qorvo Tech Forum). I transitioned from LTspice and spent a few days getting familiar with QSpice. Initially, I didn’t like it, but eventually, I found that I didn’t want to go back to working with the LTspice interface. If you are a frequent or advanced user, you will eventually find that you can draw a schematic and set things up very effectively in QSpice.

I have a quick tutorial for QSpice in this post; it only takes a few minutes and may ease the process of picking up QSpice.
Beginner Tutorial for QSpice (Community Sharing) - QSPICE - Qorvo Tech Forum

4

This is a technique that uses “add attribute” to set up two text strings, and uses “comment” to enable or disable which source statement is used. This technique can be applied to any device instance parameters.

changesrc

This is how things work in QSpice. The schematic drawing is just a GUI used to convert a circuit into a netlist. Attribute text is what actually appears in that netlist. If you comment out an attribute, it will not be included during netlist generation. Therefore, QSpice encourages you to get familiar with netlists directly from its GUI. All experienced SPICE users understand netlists, whereas people can work in LTspice for a long time without knowing much about netlist syntax as the pop up window parameter setup.
changesrc

1 Like
5

Thanks for your replies.
Adding a new attribute and commenting out the old one is a practical solution.

But I don’t use spice very often, so I occasionally forget certain commands or attributes. LTspice’s attribute menu displayed all attributes I could select, so it’s a help in this case. In QSPICE, I have to know them or have to use use a printed reference sheet to select the required attribute.
So why were the LTspice-style dialogs removed? Is it due to licensing issues, the additional maintenance effort, or do you or Mike simply not like them anymore?

6

Hi, Greybeard.

I don’t have any special inside knowledge but I’ll give you my thoughts.

  • The author of QSpice is also the author of LTSpice, Mike Engelhardt. He is a team of one.
  • Mike’s goal in developing QSpice was to “do it right this time.” That is, produce a simulator that is super-fast and super-accurate and produces correct results for hard-to-simulate electrical elements. And he added support for digital code (C-Block DLLs).
  • The early days of Spice tools were strictly text files, hand-coded netlists. At the end of the day, all Spice GUIs do is translate a visual circuit representation into a netlist.
  • In my experience, developing GUIs takes 90% of total programming effort and produces 90% of the consumer complaints.
  • Instead of spending valuable development time designing pretty pop-up dialogs (and revising them endlessly), we get a right-click “Pertinent Help File Page” link that takes us to the basic netlist parameters help page. If we had a dialog box, we’d still be clicking on help for those unfamiliar parameters.

Anyway, it is a different philosophy but, after getting acclimated, you’ll not find the lack of a pretty GUI a hindrance..

–robert

7

we get a right-click “Pertinent Help File Page” link that takes us to the basic netlist parameters help page

Thanks, I was not aware of that helpful feature.