I’m pretty new to drawing schematics. I thought I’d start by reverse engineering something I thought might be pretty easy. What I have is Silence Sensor based around an LM324N and a microcontroller. I think the LM324N is a comparator and that signal is being sent to the microcontroller which is manipulating LEDs as well as a relay. So far, I’ve only drawn the audio section.
What I’d like to do is use the simulator to see what kind of signals the OpAmp is generating. Here’s what I have so far:
Schematic looks mostly plausible, but at least the values for C30 and c31 are missing. I also recommend using GND symbols instead of PE, and to put them the right side up. (Just for easier reading).
But for starting with simulations, I suggest you start with something simpler first. There are a bunch of things that can make it difficult to get started with simulations, and building it up in small steps is recommended.
If you would like to stay within KiCad, this is what I recommend:
Circuit diagram:
Replace the earth symbol by GND symbol (indeed not a recommendation, but a must).
Connect your in and out labels.
A suitable voltage source is the VSIN symbol, used for transient (voltages versus time) simulation.
Your power supply symbol part U1E is not used adequately. You may watch this video for an example https://www.youtube.com/watch?v=Wg7uSs4J_0U.
Model:
Now the difficult part
Download the model from the TI web site. Indeed KiCad/ngspice does not provide ngspice models for simulation (except for some generic devices).
If you then have a look at the model file lmx24_lm2902.lib, you will see the line .subckt LMX24_LM2902 IN+ IN- VCC VEE OUT
it has only 5 connections, not pins number 1 to 14, as the 4-part LM324 has in its packages and your symbol U1A to U1D is showing). This is indeed stemming from the PCB-orientation of KiCad/ngspice. Other simulator don’t care about this, so the next step may be skipped with using them. There has to be some translation between the 14-pin package and the 5-pin model.
@holger, In the example above you use XU1A and XU1B But that seems to make it dependent on the RefDes. I did it like below, where the TL072 and TL074 reuse the model from the TL071. If you agree this is a better method, it may be worth to update that example on sourceforge.
