How can I plot BJT linearity of a simple emitter follower

[paulvdh]

You pretty much start by drawing a schematic. Without knowing anything more about your KiCad and (ng)Spice knowledge it’s impossible to give anything but the most generic advise.

Have you seen:

Simulation: Getting started with ngSpice and other resources

There are quite a lot sources and resources for getting started with ngSpice in KiCad, so I thought to make a list with links instead of repeating the information again and again and again and… Text Tutorials First, of course the ngSpice website itself. The link below is to how to use ngSpice with KiCad, but there is lots of other info over there, from the official ngSpice manual (ngSpice is a separate project then KiCad), to (links to) downloadable libraries with models. Videos If you prefer…

The FAQ section of this forum is much more extensive then the “average” faq list. It has got a whole lot of quite in depth articles, and also some indexes to some common questions.

I don’t know very much about ngspice myself, but in one of my dabblings I managed to make a “transistor curve tracer” simulation. Main addition is that it’s a very simple “getting started” (does the BJT model even work, pin assignment correct etc.) and that it draws multiple plots in one widow. I added the project to one of holger threads which are already summarized in the “getting started” above. A direct link is:

Simulation examples for KiCad8/KiCad9/Eeschema/ngspice

An example of a transistor curve tracer. [image] It’s a simple circuit. About the simplest you can create with a BJT, but none the less, I believe it’s useful for posting here. Not only as a beginners example, but also to verify that the both the BJT model, and the ngSpice simulator work. In Schematic Editor / Inspect / Simulator / Simulation / Edit Analysis Tab the BJT is set up with base current increments of 1uA (See “sweep type”, even though the “Increment step” shows V as units) and fo…