![]() The only parameter that’s missing between my version and the LTspice version is slew-rate, which I’m still not certain the best way to implement while retaining fast simulation speed. I structured the text such that it’s easier to read the comments and parameter descriptions when selecting the subcircuit model within Eeschema. I’ve tested both models in LTspice and KiCad 5.1.4 (for Windows). I removed all semiconductors and replaced all the diodes with voltage-controlled switches. The Level 2 is loosely based on the app note PDF I linked above. I attached a library file of my own “Universal Opamp” models, which include both Level 1 and Level 2. You just need to plug in a few datasheet values into the subcircuit parameters to get a rough approximation to the opamp you want to model. Not only is this type of behavioral model faster and has less convergence issues than semiconductor-based models, it can also be used when no model is available from the opamp manufacturer. Level 2 adds quite a bit of functionality since it includes the voltage rails in the netlist.Īnyway, to get back on topic here, I wanted to create something similar to Level 2 which can be used in ngspice so people can use it in KiCad. ![]() Level 1 is the same as the model I described above without voltage rail consideration. ![]() The first two levels are the most practical, and I constantly use them. I typically use LTspice and it has a handy built-in device called the “UniversalOpamp2” which has 4 different levels of models to pick from using a drop-down menu. However, there are times where I need to consider saturation due to the voltage rails, mainly in comparator applications. I use this model frequently in my own work since it’s fast and gets you decent results as long as you are aware of the limitations. Big improvement over doing the lot again and this should work whatever has caused the problem.I’ve been intending to do this for a while now, but haven’t really gotten the chance to figure it out until some recent toilet reading of this PDF: Ī while back, I posted a super simple opamp subcircuit which is purely linear and doesn’t take the voltage rails into account. A simple fix might be an option to delete all wires from the schematic and from internal storage so that the user can wire it up again. The only solution is to throw the lot away and start again. Having the net calculation fail is extremely frustrating. The net effect seems to be short sections of wire under the one that has been drawn that remain when the one on top is deleted. Mouse clicks set where the wire changes direction. ![]() It would be best to disable this attempt at automation and keep the wire straight as the changes it makes generally wont be suitable anyway. In fact they only seem to select with a right click. I do correct the position of the end of the wire to obtain a straight line but sometimes when I delete a line a couple of small wires are left behind that are hard to select and delete. Drift off a straight line and it will try and auto correct the path of the wire. I think this may have something to do with the way wires behave when they are drawn. One other problem, Net generation failing after changes have been made to the circuit. Adding a high pass rc filter to the output also prevents simulation. I've been trying to use qucs for some audio type work using a tl071 on a single rail. ![]()
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